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Types of Contact Lens

As long ago as 1912, a glass contact lens was being produced, but because of the manufacturing difficulties and wearing problems, the widespread use of this type of optical aid was delayed until the introduction of plastic scleral lenses in 1937. The obvious advantage of placing a lens directly on the cornea over the wearing of spectacles is the cosmetic one, but the system also has optical advantages. Because the lens moves with the eye, there are none of the problems associated with looking through the edge of the lens experienced by the wearer of spectacles. In addition, a more subtle effect is the more accurate representation of image size on the retina in subjects with high degrees of refractive error. Although the original type of moulded scleral contact lenses are still occasionally used, they have been largely replaced by the modern rigid and soft lenses, which are much smaller and thinner and hence cause less interference with corneal physiology. Rigid lenses are made from...

Congenital or Developmental Glaucoma

These glaucomas occur in eyes in which an anomaly present at birth produces an intraocular pressure rise. This type of glaucoma is extremely rare and it is often, though not always, inherited. This means that the affected child might be brought to the ophthalmologist by the parents because they are aware of the condition in the family. Children could be born with raised intraocular pressure and for these cases, the prognosis is not so good as in those where the pressure rise does not occur until after the first few months of life. In primary developmental glaucoma, the glaucoma is caused by a defective development of the angle of the anterior chamber, and gonioscopy shows that the normal features of the angle are obscured by a pinkish membrane. Raised intraocular pressure in infancy has a dramatic effect because it causes enlargement of the globe. This can best be observed by noting an increase in the corneal diameter. The enlarged eye has given the condition the name of buphthalmos...

Acute Angleclosure Glaucoma

This condition is less common than chronic open-angle glaucoma, making up about 5 of all cases of primary glaucoma. It is a much more dramatic condition than the chronic disease and fits in more closely with the popular lay idea of glaucoma . It tends to affect a slightly younger age group than chronic glaucoma and only occurs in predisposed individuals. There is a particular type of eye that is liable to develop acute glaucoma this is a small hypermetropic eye with a shallow anterior chamber. One rarely meets a myope with acute glaucoma in Caucasians (in Asian populations, however, angle closure and myopia more often coexist).

Testing Visual Acuity

Measurement of visual acuity is the most important part of the ocular assessment performed by the doctor and yet it is surprising how often the nonspecialist omits it in examination. It has already been shown that the differential diagnosis of the red eye can be simplified by noting the vision in the affected eye. After injuries of the eye, it is just as important to note the vision in the uninjured eye as in the injured eye. Simple measurement of visual acuity is of limited value without a knowledge of the spectacle correction or whether the patient is wearing the appropriate spectacles. The best corrected visual acuity (i.e., with lenses in place) therefore needs to be recorded for each eye. This corrected visual acuity can also be estimated with a pinhole held in front of the eye. The effect of the pinhole is to eliminate the effect of refraction by the cornea and the lens on the extremely thin beam of light produced by the pinhole. Measuring the visual acuity means measuring the...

Sulfonamides In The Treatment Of Glaucoma

Glaucoma is a chronic, degenerative eye disease, characterized by high IOP, which causes irreversible damage to the optic nerve head, and, as a result, the progressive loss of visual function and eventually blindness (Bartlett and Jaanus 1989 Maren 1992, 1995). Elevated IOP (ocular hypertension) is generally indicative of an early stage of the disease (Bartlett and Jaanus 1989 Soltau and Zimmerman 2002 Hoyng and Kitazawa 2002). CAIs represent the most physiological treatment of glaucoma, because by inhibiting the ciliary process enzyme (the sulfonamide susceptible isozymes CA II and CA IV), a reduced rate of bicarbonate and aqueous humor secretion is achieved, which leads to a 25 to 30 decrease in IOP (Maren 1967, 1992, 1995). Acetazolamide 8.1, methazolamide 8.2, ethoxzolamide 8.3 or dichlo-rophenamide 8.4 were and are still extensively used as systemic drugs in the therapy of this disease (Maren 1967 Supuran and Scozzafava 2000, 2001, 2002 Supuran et al. 2003), as they all act as...

Vision and Eye Disorders

The two most important aspects of vision in relation to driving are visual acuity and visual fields. Visual acuity may simply be defined as the best obtainable vision with or without spectacles or contact lenses. Most countries require a binocular visual acuity greater than 6 12 for licensing purposes. In the United Kingdom, the eyesight requirements are to read a car number registration plate at 20.5 m, which corresponds to between 6 9 and 6 12 on the Snellen chart. The minimum field of vision for safe driving is generally regarded as at least 120 on the horizontal when measured with a Goldman IV4e target or its equivalent (14).

The Scope of Ophthalmology

Although the eye and its surrounding structures would seem to provide an ideal anatomical and functional basis for specialisation, ophthalmology can no longer regard itself as a specialty on its own but more the heading for a group of sub-specialties. There are those who know all about the pigment epithelium of the retina and yet bow to those who have a special knowledge of the bipolar cells in the retina. Over the past 100 years the science has advanced at an unbelievable rate and with the increase in our knowledge has come the development of treatments and cures, which have had a great impact on our everyday lives. Most of the work of the ophthalmologist is necessarily centred on the globe of the eye itself, and there are a number of conditions that are limited to this region without there being any apparent involvement of the rest of the body. Ophthalmology is usually classified as a surgical specialty but it provides a bridge between surgery and medicine. Most of the surgery is...

Form Deprivation Myopia

Increased synthesis and accumulation of aggrecan, which increases the volume of extracellular matrix in the posterior sclera, are responsible for the ocular enlargement observed in form-deprived chick myopia (161). Synthesis of scleral proteoglycans including aggrecan is higher during the day than at night, but there are no significant differences between rhythms in scleras from normal and form-deprived eyes (162). The turnover rate of scleral proteoglycans is vision-dependent and is accelerated in the posterior sclera during the development of experimental myopia (163). Treatment with beta-xyloside, a specific inhibitor of proteoglycan synthesis, results in a significant reduction in the axial length, vitreous chamber depth and rate of axial elongation of form-deprived eyes (164).

Eye Disease in the Elderly

A recent survey in the USA has shown that the incidence of cataract in the 45-64-year-old population is 5.6 for males and 2.1 for females. The incidence is slightly higher in the Negro population, and rises to 21.6 for males and 26.8 for females in the 65-75-year-old population. In the same age group (65-75 years), the incidence of AMD is 9.6 for males and 6.9 for females. Both these conditions are, therefore, common and they demand time and medical expertise, both at the primary care level and in hospital. With increasing longevity throughout the world, especially in the developing countries, there will be a continuing increase in the number of blind people, especially those suffering from diseases related to age, such as cataracts, glaucoma and macular degeneration.

Normalpressure Glaucoma

This condition is similar to primary open-angle glaucoma except that the intraocular pressure is within normal limits (i.e., 21 mmHg or less at the initial and subsequent visits). The condition is probably caused by low perfusion pressure at the optic nerve head so that the nerve head is susceptible to damage at normal intraocular pressure. Certain conditions that can mimic normal pressure glaucoma include compressive lesions of the optic nerve and chiasma, carotid ischemia and congenital optic disc anomalies. Treatment of normal-pressure glaucoma aims to reduce intraocular pressure to 12mmHg or less.

Primary Openangle Glaucoma

The first important point to note about this disease is that it is common, occurring in about 1 of the population over the age of 50 years. The second point is that the disease is inherited, and whereas the practice of screening the whole population for the disease is problematic in terms of finance, it is well worth screening the families of patients with the disease if those over the age of 40 years are selected. This leads to the third point, which is that the incidence increases with age, being rare under the age of 40 years. This insidious, potentially blinding disease affects those who are least likely to notice its onset, and elderly patients with advanced chronic open-angle glaucoma are still seen from time to time in eye clinics. Primary open-angle glaucoma occurs more commonly in high myopes and diabetics patients with Fuchs' corneal endothelial dystrophy and retinitis pigmentosa also have a higher incidence. Glaucoma is commoner in different racial groups. For example,...

Making a Career in Ophthalmology

Ophthalmology is a popular specialty and so the aspiring eye surgeon can expect considerable competition. There are certain essential requirements. First, an initial interest in physics and In many cases, an interest in the subject is aroused in medical school by a mentor or a good teacher. By and large, those who see ophthalmology as a soft option are not happy in their career. Those who, as most doctors do, set out to improve the lot of the patient, find the specialty very rewarding because it is undoubtedly extremely effective in this respect. In the UK, medically qualified graduates can start their eye training with a senior house officer (SHO) job and thence look for a specialist registrar post in one of the training centres. A question sometimes asked is what jobs as an SHO, other than ophthalmology, are best suited to an eventual career in ophthalmology. Obvious ones are in plastic surgery, neurology or neurosurgery but sometimes a seemingly unrelated one can prove to be good...

Drugs in the Treatment of Allergic Eye Disease

With the increasing incidence of atopy, the treatment of allergic eye disease has gained in importance in recent years. Treatments are designed to interfere with either the type 1 (immunoglobulin E IgE -mediated) or type 4 (delayed) hypersensitivity response, both of which are thought to be important in disease pathogenesis. For mild disease, initial treatment should involve antigen avoidance (if known) and frequent use of artificial tears (hypromel-lose) to wash away antigens from the ocular and conjunctival surface. Treatment of more severe disease involves the use of systemic or topical antihistamines (levocabastine, emedastine and azelastine), which are helpful for relief of symp

Dyschromatopsias Associated with Neuro Ophthalmic Disease

People with congenital dyschromatopsias are frequently not aware that their color perception differs from those with normal, trichromatic color vision. Others have learned to adapt to their limited perception of certain colors. Thus, a person with faulty red green color discrimination will often describe a dark green color as red. Some of these people know that they cannot properly identify colors accurately in certain ranges of hue and luminance. Patients with acquired dyschromatopsias are often unaware of the changes in their color perception, due to the subtle onset and gradual progression of the damage. Not infrequently, this allows major color vision disturbances to go unnoticed. Unilateral dyschromatopsias - if not associated with cataract - should be examined with tests of color saturation in the affected eye, since this is frequently the clinical presentation for an optic neuropathy. Other neuro-ophthalmic disorders (see Table 6.1) should initiate a targeted search for an...

Drugs and Contact Lenses

As a rule, contact lenses should not be worn when the eye is being treated with drops. The exception is when the contact lenses themselves are being used for some therapeutic purpose. Soft hydrophilic contact lenses can take up and store the preservative from some kinds of drop. The preservative benzalkonium chloride is especially liable to be absorbed onto a contact lens. When it is essential that drops are administered to a patient wearing contact lenses, it is often possible to prescribe in the form of single-dose containers that do not contain a preservative.

Thyroid Eye Disease

Thyroid eye disease is an immunological disorder that affects the orbital muscles and fat. Hyperthyroidism is observed with orbitopathy at some point in most patients, although the two are commonly synchronous. Histological examination of the retroocular connective tissues in thyroid eye disease reveals lymphocytic infiltration and accumulation of glycosaminoglycans produced locally by fibro-blasts, which contribute to the pathogenesis of ophthalmopathy. Effective parameters involving glycosaminoglycans to indicate the activity of thyroid eye disease have been reported. The concentrations of glycosaminoglycans were determined in patients with thyroid eye disease and control subjects (68). The orbital extracellular matrix glycosaminoglycans exhibited a significant increase in the tissue fractions containing chondroitin sulfate A and hyaluronan in patients with thyroid eye disease in comparison to those from control subjects. Patients with increased glycosaminoglycan concentrations...

Disease Basis 61231 Glaucoma

Elevation of IOP results from a deposition of extracellular matrix (ECM) in the anterior chamber, and thus blockage of the AH drainage pathway, the TM and Schlemm's canal. The ECM is composed of numerous proteins, modified glycoproteins, and glycosaminoglycans, including hyaluronic acid, chondroitin sulfate, dermatan sulfate, keratin sulfate, and heparin sulfate. The abnormal deposition and or clearance of ECM in glaucomatous patients may also result from TM cell death and loss of phagocytic activity during the aging process. Coupled with these phenomena is perhaps the decreased ability of TM cells to liberate local matrix metalloproteinases (MMPs), that can digest the ECM and remodel and maintain the anterior chamber architecture and function. There is increasing evidence that increased concentration of tissue growth factor- 2 (TGF-P2) observed in ocular hypertensive glaucoma patients contributes to the elevation of ECM in the TM. The loss of MMP activity could also be due to TGF-...

The Cataract Operation

Every medical student should witness at least one cataract operation during the period of training. It is an example of a classical procedure, which has been practiced for 3000 years. The earliest method for dealing with cataract was known as couching. This entailed pushing the lens back into the vitreous, where it was allowed to sink back into the fundus of the eye. Although this undoubtedly proved a simple and satisfactory procedure in some instances, there was a tendency for the lens to set up a vigorous inflammatory reaction within the eye, with subsequent loss of sight. Modern cataract surgery was founded by the French surgeon Jacques Daviel in the eighteenth century. The operation that he devised involved seating the patient in a chair and making an incision around the lower half of the cornea. The lens was then removed through the opening. The results claimed were remarkable considering the technical difficulties that he must have encountered. Subsequently, the procedure was...

Micronutrients Cataracts

For prevention of cataract cataractdevelop- Fig. 5.2 Vitamin Eand cataracts. Among 300 individuals taking supplemental vitamin E ( 400 mg day), the prevalence of cataract was 56 lower than in those not consuming supplements. Another study found the prevalence of nuclear cataract in 671 adults to be 48 less among individuals with higher plasma concentrations of vitamin E.

Amblyopia of Disuse

This has been defined as a unilateral impairment of visual acuity in the absence of any other demonstrable pathology in the eye or visual pathway. This rather negative definition fails to explain that there is a defect in nerve conduction because of inadequate usage of the eye in early childhood. The word amblyopia means blindness and tends to be used rather loosely by ophthalmologists. It is most commonly used to refer to amblyopia of disuse ( lazy eye ) but it is also used to refer to loss of sight caused by drugs. Amblyopia of disuse is common and some patients even seem unaware that they have any problem until they suffer damage to their sound eye. This weakness of one eye results when the image on the retina is out of focus or out of position for more than a few days or months in early childhood or, more specifically, below the age of eight years. Amblyopia of disuse, therefore, arises as the result of a squint or a one-sided anomaly of refraction, or it can occur as the result...

Drugs in the Treatment of Openangle Glaucoma

There has been a small revolution involving the type of eye drops used for the treatment of glaucoma in recent times. For years, the mainstay of treatment was pilocarpine and the topical beta-blockers, for example timolol, but the potential systemic side effects of these drugs have led to the introduction of other novel types of ocular hypotensive agents. In general, these new agents can be divided into alpha2-adrenergic agonists, carbonic anhydrase inhibitors and prostaglandin analogues. All these medications have the problem of compliance. Elderly patients may forget to instill drops on a regular basis. In some cases, even instillation of three different glaucoma drops fails to control the intraocular pressure. In these instances, the only sure way of lowering the pressure is by glaucoma drainage surgery.

Glycosaminoglycans in Eye Diseases A Macular Corneal Dystrophy

Figure 1 Schematic diagram of the eye in horizontal section indicating each ocular component. a, corneal epithelium b, keratocyte c, corneal endothelium d, aqueous humor e, conjunctiva f, sclera g, trabecular meshwork h, iris i, lens j, ciliary zonule and body k, vitreous l, retina m, interphotoreceptor matrix n, retinal pigment epithelium o, Bruch's membrane p, choroid q, optic nerve head r, lamina cribrosa s, extrao-cular muscles and tissues. The candidate glycosaminoglycans involved in the ocular components of each eye disease described in this chapter are as follows macular corneal dystrophy (b, c KS, CS DS, HA), glaucoma (d HA g CS DS, HS, HA q, r CS, HS, HA), cataract (i CS DS, HS, HA), diabetic retinopathy (k HA l HS), retinal detach-ment proliferative vitreoretinopathy (k, l, m, n CS DS, HS, HA), myopia (f, p CS), thyroid eye disease (s CS, HA), pseudoexfoliation syndrome (c, d, g, h, i, j KS, CS DS, HA). KS, keratan sulfate CS DS, chondroitin sulfate dermatan sulfate HS,...


The simplest assay system is represented by cells grown in vitro. Isolated cells of the TM, ciliary muscle, and ciliary process, and various retinal neurons in culture have proven useful for validating disease targets, for studying the mechanisms of action of ocularly indicated drugs, for studying the etiologies of ocular hypertension and glaucoma, and for discovering new drugs for treating ocular hypertension and glaucoma. For example, human CM and TM cells33 have mRNAs and functionally active receptors for FP-class PGs that potently and efficaciously lower IOP in nonhuman primates and humans. These cells release MMPs4,34 in response to FP-receptor activation and are involved in digesting the ECM in the anterior chamber, thereby enhancing the AH efflux and lowering IOP. Similar human TM and CM cell-based studies have demonstrated the existence of the cellular machinery for 5HT2 receptor agonists, which also induce Clearly, the best models to study glaucoma are animals and human...


This common condition in the elderly eye has already been considered, but it is important that every physician can identify and assess the density of a cataract in relation to the patient's vision. The physician must realise the potential of cataract surgery in the restoration of vision. Cataract surgery is required only if vision is sufficiently reduced so far as to interfere with the patient's normal lifestyle. The contraindications for cataract surgery are few and even in extreme old age the patient can benefit. Surgery might be delayed if the patient has only one eye or if there is some other pathology in the eye, which is likely to affect the prognosis. The need for someone to assist the patient in the instillation of eye drops and the domestic chores during the postoperative period might require some attention but is not a contraindication. About one-third of the population aged over 70 years suffers from a cataract, but the quoted figures vary according to the diagnostic...

Druginduced Glaucoma

Local and systemic steroids can cause a rise in intraocular pressure and this is more likely to occur in patients with a family history of glaucoma. Steroid glaucoma is a well-recognised phenomenon and steroid responders can be identified by measuring the intraocular pressure before and after instilling a drop of steroid. The less potent steroids, hydrocortisone and pred-nisolone, are less likely to cause this problem and other steroids have been manufactured that have less effect on intraocular pressure, but the anti-inflammatory strength is significantly weaker. The use of systemic steroids can be associated with glaucoma asthmatics who use steroid inhalers frequently are at a significantly greater risk of developing glaucoma. The possibility of inducing an attack of acute glaucoma by drugs has already been mentioned.

Visual Acuity

Without glasses) E.g., cataract Young children and illiterates can be asked to do the E test, in which they must orient a large wooden letter E so that it is the same way up as an indicated letter E on a chart. Perhaps better than this is the Stycar test (Figure 3.2), in which the child is asked to point at the letter on a card that is the same as the one held up at 6 m. Other ways of measuring visual acuity are discussed in Chapter 17.

Congenital Cataract

The lens can be partially or completely opaque at birth. Congenital cataract is often inherited and can be seen appearing in a dominant manner together with a number of other congenital abnormalities elsewhere in the body. The condition might also be acquired in utero, the best known example of this being the cataract caused by rubella infection during the first trimester of pregnancy remember the triad of congenital heart disease, cataract and deafness in this respect. Minor degrees of congenital cataract are sometimes seen as an incidental finding in an otherwise normal and symptom-less eye. The nature of the cataract usually helps with the diagnosis. The lens fibres are laid down from the outside of the lens throughout life. If the opaque lens fibres are laid down in utero, this opaque region can remain in the centre of the lens. Only when the cataract is thick does it present as a white appearance in the pupil and often it is difficult to detect it. It is important to examine the...

Diet Healthy Eyes

To maintain good eyesight foods rich in vitamins A, C, E, riboflavin, selenium, and zinc should be consumed. All these nutrients are important for vision and are supplied by a balanced diet with generous amounts of fruits and vegetables, such as carrots, cantaloupe, oranges, and broccoli. Generous intake of antioxidant nutrients (see pp. 115) over a lifetime may help prevent cataract, the most common cause of impaired vision in older adults.1 Age-related macular degeneration (AMD) is a common cause of vision impairment in older people, and the risk of AMD can be reduced by a diet high in antioxidants, ca-rotenoids, and zinc.2 3 Nutrient supplementation may help correct minor eye troubles such as dry, burning, itchy eyes and eyestrain.

Neovascular Glaucoma

The elderly patient who presents with a blind and painful eye and who might also be diabetic should be suspected of having neovascular glaucoma. Often, a fairly well-defined sequence of events enables the diagnosis to be inferred from the history, as in many cases secondary neo-vascular glaucoma arises following a central retinal vein occlusion. Following retinal vein occlusion, patients typically notice that the vision of one eye becomes blurred over several hours or days. Some elderly patients do not seek attention at this stage and some degree of spontaneous recovery can seem to occur before the onset of secondary glaucoma. Fortunately, only a modest proportion of cases develops this severe complication, which usually occurs, surprisingly enough, after 100 days, hence the term hundred-day glaucoma . Once the intraocular pressure rises, the eye tends to become painful and eventually degenerates in the absence of treatment, and sometimes even in spite of treatment. This form of...


It is found in most ophthalmic departments that it is necessary to retain a close liaison with neurological and neurosurgical departments, and neuro-ophthalmology is now in itself a sub-specialty. Retrobulbar neuritis, for example, is a condition that presents quite commonly to eye casualty departments and usually requires further investigation by a neurologist. Less common but equally important are the pituitary tumours, which, it will be seen, can present in a subtle way to the ophthalmologist and can require urgent medical attention. There are many other, sometimes rare, conditions, which find common ground between the disciplines.

Diet Cataracts

Most cataracts are caused by oxidative damage from lifetime exposure of the lens to light and radiation entering the eye. The antioxidant vitamins A, C, and E are a major defense against oxidative damage, and eating foods rich in these nutrients each day can reduce the risk of cataract (see Fig. 5.2).1 Regular consumption of galactose, found in the milk sugar lactose, may cause cataracts in people with inherited defects in galactose metabolism. In cases of an inability to metabolize galactose, milk and dairy product consumption should be sharply restricted. Hyperlipidemia, diabetes, and obesity also increase the risk of cataract. All these conditions are modifiable by dietary changes and nutritional supplementation.

Acute Glaucoma

The important feature here is that acute glaucoma occurs in long-sighted people and there is usually a previous history of headaches and seeing haloes around lights in the evenings. The raised intraocular pressure damages the iris sphincter and for this reason, the pupil is semi-dilated. Oedema of the cornea causes the eye to lose its luster and gives the iris a hazy appearance (Figure 7.3). The eye is extremely tender and painful and the patient could be nauseated and vomiting. Immediate admission to hospital is essential, where the intraocular pressure is first controlled medically and then bilateral laser iridotomies or surgical peripheral iridec-tomies are performed to relieve pupil block. Mydriatics should not be given to patients with suspected narrow-angle glaucoma without consultation with an ophthalmologist.

Traumatic Cataract

Two eyes makes it impossible to wear glasses. This is partly because everything looks much bigger with the corrected aphakic eye the image on the retina is abnormally large. By wearing a contact lens on the cornea, the optical problems might be solved,but it is an unfortunate fact that patients with traumatic cataracts usually have working conditions that are unsuited to the wearing of a contact lens.

Other Tests Available in an Eye Department

Several special tests are available to measure the ability of the eyes to work together. A department known as the orthoptic department is usually set aside within the eye clinic for making these tests. When there is a defect of the ocular movements, this can be monitored by means of the Hess chart (see Chapter 14). The ability to use the eyes together is measured on the synop-tophore, and any tendency of one eye to turn out or in can be measured with the Maddox rod and Maddox wing test (Figure 3.16). The use of contact lenses and also of intraocular implants has demanded more accurate measurements of the cornea and of the length of the eye. A ker-atometer is an instrument for measuring the curvature of the cornea, and the length of the eye can now be accurately measured by ultrasound. If one eye appears to protrude forwards and one wishes to monitor the position of the globes relative to the orbital margin, an exoph-thalmometer is used (Figure 3.17). X-rays of the eye and orbit are...

The Abnormally Dilated Pupil

Acute narrow-angle glaucoma can occasionally present in this manner and confusion can arise if the eye is not red however, closer examination of the eye should make the diagnosis obvious. Because the nerve fibres, which cause constriction of the pupil, are conveyed in the oculomotor nerve,oculomotor palsy if complete, is associated with mydriasis. For this reason, dilatation of the pupil can be a serious sign of raised intracranial pressure after head injury. One pupil might be wider than the other as a congenital abnormality (congenital anisocoria).

Sexlinked Recessive Inheritance

It has been mentioned already that males have the XY configuration of sex chromosomes, whereas females have XX . Because of the unpaired nature of much of the male sex chromosomes, some recessive genes can have an effect in males when they do not do so in the female. Certain important eye conditions are carried in this way in pathological genes on the that it is possible to predict the likely disease incidence in offspring. It should also be realised that such predictions can only be based on careful and extensive investigation of the family. Although some eye diseases are known to follow a fixed pattern of inheritance, others, notably retinitis pigmentosa, can be inherited in different ways in different families. In most large centres, there are now genetic clinics in which time is devoted specifically to the investigation of families and also to the detection of carriers.

Damage to the Eyes by Drugs Administered Systemically

Apart from causing glaucoma in some patients, systemic steroids are thought to increase the rate of formation of cataracts. Ethambutol and isoniazid can cause optic atrophy. Sometimes excessive doses of quinine are taken as an abortifacient and as the patients regain consciousness they are found to be blind from quinine toxicity. Methyl alcohol is toxic to the ganglion cells of the retina and blindness is a hazard of meths drinkers. It sometimes contaminates crudely prepared alcoholic beverages leading to unexpected loss of vision. The list of drugs with ocular side effects is large and the reader should consult a specialised textbook for more information. Nowadays, disasters and indeed lawsuits should be avoidable if the drug literature is checked before prescribing an unfamiliar drug.

Traumatic Optic Neuropathy Definition

Traumatic optic neuropathy results primarily from indirect injury, rather than by direct crushing or tearing mechanisms. A direct blow to the eye can cause an avulsion of the optic nerve (more properly called an expulsion). The mechanism appears to be one of a sudden, explosive increase in intraocular pressure with rupture of the scleral coat in a circumpapillary ring where the sclera is very thin. Most often, this occurs in patients that have moderate to high degrees of axial myopia and or a posterior staphyloma. The eye has no light perception, the pupil is fixed in mid-dilation, and ophthalmoscopy reveals disappearance of the optic disc, with folds of retina that have been dragged through the posterior rupture. Another mechanism appears to be a small-vessel infarction of the intracanalicular portion of the nerve, presumably caused by shearing of the perineural blood vessels. This commonly happens without a fracture, and there is initially no ophthalmoscopic abnormality. The eye has...

When the Fundus Is Abnormal

Quite a proportion of patients who complain of loss of vision with eyes that look normal on superficial inspection show changes on ophthalmoscopy. The three important potentially blinding but eminently treatable ophthalmological conditions must be borne in mind cataract, chronic glaucoma and retinal detachment. It is an unfortunate fact that the commonest cause of visual loss in the elderly is usually untreatable at the present time. It is known as age-related macular degeneration and forms part of the sensory deprivation, which is an increasing scourge in elderly people. These diseases are Finally, there are a large number of less common conditions, only one or two of which will be mentioned at this point. At any age, the ingestion of drugs can affect the eyesight, but there are very few proven oculotoxic drugs still on the market. One important example is chloroquine. When a dose of 100 g in one year is exceeded, there is a risk of retinotoxicity, which might not be reversible....

Adenoviral Conjunctivitis

Symptoms follow an upper respiratory tract infection and, although nearly always bilateral, one eye might be infected before the other. The affected eye becomes red and discharges characteristically, the eyelids become thickened and the upper lid can droop. The ophthalmologist's finger should feel for the tell-tale tender enlarged preauricular lymph node. In some cases, the cornea becomes involved and subep-ithelial corneal opacities can appear and persist for several months (Figure 6.4). If such opacities are situated in the line of sight, the vision can be impaired. There is no known effective treatment but it is usual to treat with an antibiotic drop to prevent secondary infection.

Treatment and Management

The treatment involves the administration of local steroids and mydriatic drops. When the condition is severe, a subconjunctival injection of steroid should be given and relief of symptoms can be further achieved by local heat in the form of a warm compress. Atropine is the mydri-atic of first choice except in the mildest cases, when homatropine or cyclopentolate drops can be used. Steroid drops should be administered every hour during the acute stage and then gradually tailed off over a period of a few weeks. Systemic steroids are not usually indicated and should be reserved for those cases in which the sight becomes seriously jeopardised. If any underlying systemic disease is identified, then, of course, this should also be treated if effective treatment is available. The proper management of anterior uveitis demands the expertise of a specialist ophthalmologist and, when the condition is affecting both eyes, it might be preferable to admit the patient to hospital.

Sensory Congenital Nystagmus

The roving eye movements are described as pendular, the eyes tending to swing from side to side. Examination of the eyes reveals one of the various underlying causes congenital cataract, albinism, aniridia, optic atrophy or other causes of visual impairment in both eyes. A special kind of retinal degeneration known as Leber's amaurosis can present as congenital nystagmus. The condition resembles retinitis pigmentosa, being a progressive degeneration of the rods and cones, and occurs at a young age. It tends to lead to near blindness at school age. Patients with congenital nystagmus usually need to be examined under general anaesthesia, and elec-troretinography (a technique that can detect retinal degenerations at an early stage) should be performed at the same time.

Of Neuro Ophthalmic Emergencies

Ninety percent of clinical neuro-ophthalmology is in the taking of a history (after W.F. Hoyt). Attentive listening, specific questioning and careful evaluation of the information gained make up the foundation of what is primarily a diagnostic subspecialty. The effort invested in gathering this information saves time and avoids unnecessary, potentially dangerous and or expensive diagnostic procedures. When taking the current ophthalmic history, it is of particular importance to determine as precisely as possible the point in time and the speed with which the initial symptoms presented. The longer it has been since the onset of symptoms and the more slowly they may have developed, the more difficult it will be to obtain this information. One should also obtain an accurate account of the eliciting factors, the temporal relationships, accompanying symptoms, and subsequent course of events. Knowledge of these details will allow a quick initial recognition of the more likely sources and...

Untreatable Causes of Failing Vision

Ophthalmologists are sometimes asked if the sight can be restored to a blind eye and, as a general rule, one can say that if there is no perception of light in the eye, it is unlikely that the sight can be improved, irrespective of the cause. There are several ophthalmological conditions for which there is no known effective treatment and it is sometimes important that the patient is made aware of this at an early stage in order to avoid unnecessary anxiety, and perhaps unnecessary visits to the doctor. Most degenerative diseases of the retina fail to respond to treatment. If the retina is out of place, it can be replaced, but old retinae cannot be replaced with new. So far, there has been no firm evidence that any drug can alter the course of inherited retinal degenerations, such as retinitis pigmentosa, although useful information is beginning to appear about the biochemistry and genetics of these conditions. Age-related macular degeneration tends to run a progressive course in...

Herpes Zoster Ophthalmicus

Occurs with remarkably little scarring of the skin considering the appearance in the acute stage. However, the cornea can be rendered permanently anaesthetic and the affected area of skin produces annoying paresthesiae, amounting quite often to persistent rather severe neu-ralgia,which can dog the patient for many years. Other complications include extraocular muscle palsies or rarely, encephalitis. Iridocyclitis is fairly common and glaucoma can develop and lead to blindness if untreated. At present, there is no known effective treatment other than the use of local steroids and acyclovir for the uveitis, and acetazolamide or topical beta-blockers for the glaucoma. Administration of systemic acyclovir or famciclovir early in the disease is known to reduce the severity of the neuralgia, but these medications need to be administered as soon as possible after the onset of symptoms for best effect. The disease has to run its course and the patient, who is usually elderly, could require...

Maintenance of Intraocular Pressure

The relative parts played by ciliary epithelium and trabecular meshwork in maintaining what is a remarkably constant intraocular pressure throughout life are not fully understood. It would appear that the production of aqueous is an active secretion, whereas the drainage is more passive, although changing the tone of the ciliary muscle can alter the rate of drainage. In normal subjects, the intraocular pressure does not differ in the two eyes by more than about 3 mmHg. Wider differences can lead one to suspect early glaucoma, especially if there is a family history of the disease. The normal intraocular pressure undergoes a diurnal variation, being highest in the early morning and gradually falling during the first half of the day. This diurnal change could become exaggerated as the first sign of glaucoma.

Infranuclear Disorders of Ocular Motility

Infranuclear disorders of ocular motility are marked by abnormal eye movements caused by lesions below the level of the cranial nerve nuclei. These lesions include damage to the cranial nerves, the extraocular muscles, or the connective tissue of the orbit. Their origins range from relatively harmless disorders to severe diseases that are life threatening. Infranuclear disorders produce paretic and or mechanical strabismus with severe deficits of visual perception by means of diplopia (image duplication), visual confusion (image overlap), and acutely by oscillopsia (illusory movement of the environment). The principle responsibility of the ophthalmologist is to provide some symptomatic relief, determine the most likely source of the problem, and to arrange for appropriate consultation with other clinical disciplines. The search for these goals requires a thorough exploration of the history, precise measurements of ocular motility, and attention to potential accessory signs and...

Optic or Retrobulbar Neuritis

The diagnosis at the time of the acute attack relies on the history and noting the pupil reaction. It is often advisable to make the diagnosis in retrospect. The patient might give a history of visual loss in one eye, which has recovered, and at a later date, presents with other nonocular signs and symptoms of demyelinating disease. If it can be confirmed that the patient has had a previous attack of optic neuritis, this can help in the confirmation of the diagnosis of disseminated sclerosis. Under these circumstances, the pallor of the disc can be helpful, but careful assessment of the colour vision, visual acuity and measurement of the visually evoked potential can provide conclusive evidence. At the time of the acute attack, testing the visual field might reveal a central scotoma. The size of this defect diminishes as healing occurs, often leaving a small residual defect between blind spot and central area.

Secondary to Disease in the

More or less any terminal event in the eye tends to be associated with cataract. Advanced uncontrolled glaucoma is often associated with an opaque lens, as are chronic iridocyclitis and intraocular tumours. Certain specific eye diseases are accompanied by cataract for example, patients who suffer from the inherited retinal degeneration, retinitis pigmentosa, sometimes develop a particular type of opacity in the posterior part of the lens. The removal of such a cataract can sometimes restore a considerable amount of vision, at least for a time.

Agerelated Macular Degeneration

AMD is the commonest cause of incurable blindness in the elderly in western countries. It is a bilateral disease in which visual loss in the first eye usually occurs at about 65 years of age. The second eye is involved at the rate of approximately 10 per annum and accounts for half of all registered visual impairments in the UK. In the early stages of dry AMD, inspection of the fundus shows spots of pigment in the macular region. Drusen are also often seen (Figure 19.1). These are small round yellowish spots, often scattered over the posterior pole. Unfortunately, the word drusen has been used rather loosely in ophthalmology to refer to two or three types of swelling seen in the fundus. It is used to describe the rare mulberry-like tumours seen around the optic nerve head in tuberose sclerosis and it is also used when referring to the multiple shiny excrescences seen on the optic disc as a congenital abnormality. Drusen seen at the posterior pole of the eye as a senile change are also...

Excessive Secretion of Tears

A wide range of conditions affecting the eye can cause an excessive production of tears, from acute glaucoma to a corneal abscess, but these do not usually present as a watering eye because the other symptoms, such as pain or visual loss, are more evident to the patient. Occasionally the unwary doctor can be caught out by an irritative lesion on the cornea, which mimics the more commonplace lacrimal obstruction. For example, a small corneal foreign body or an ingrowing eyelash can present in this way. Not uncommonly, a loose lash may float into the lower lacrimal canaliculus where it might become lodged, causing chronic irritation at the inner canthus. Its removal after weeks of discomfort produces instant relief and gratitude.

Lebers Hereditary Optic Neuropathy Definition

The visual acuity in LHON is reduced to 20 200 or worse. The visual field shows a large, central or cecocentral sco-toma, and color perception is badly damaged. The acute phase is marked by a peripapillary microangiopathy with irregular areas of microvascular dilation, tortuosity, and variations in caliber sometimes described as telangiecta-sias. The next stage (within a few weeks) is marked by increasing optic disc pallor and a disappearance of the initial microangiopathy. It is notable that the microangiopathy can be found in asymptomatic carriers of the maternally inherited deficit.

Malignant Hypertension

Occasionally,patients with a severe hypertensive problem present directly to the ophthalmologist because their main symptom is blurring of the vision, the other more usual symptoms being less evident. On examination, the visual acuity might be only slightly reduced unless there is significant macular oedema and there might be some enlargement of the blind spot and constriction of the visual fields. Inspection of the fundus reveals marked swelling of the optic disc, the oedema often extending well away from the disc with scattered flame-shaped haemorrhages. If the diastolic blood pressure is above 110-120mmHg, there is little doubt about the diagnosis, but below this level it is essential to bear in mind the possibility of raised intracranial pressure from other causes. When hypertension is as severe as this, the patient should be treated as an acute medical emergency and referred without delay to the appropriate physician.

Toxic Optic Neuropathies Definition

Ethambutol and other antitubercular drugs, cytostatic agents, heavy metals, hexachlorophene, and methanol can all cause a toxic optic neuropathy (also see Chap. 17). The first priority is to identify the offending agent and then to block further exposure. Specific measures that follow are determined by the nature of the toxin. The most common syndrome of toxic damage to the optic nerve chiasm is that of tobacco-alcohol amblyopia. It is thought that the toxin in question is cyanide, which is present in trace quantities in tobacco smoke. Interventional therapy with oral multivitamins (e.g., vitamin B complex) and intramuscular injections of hydroxycobalamine (the decyanated form of vitamin B12) can reverse the visual loss in the early stages of the disease. These vitamins are thought to chelate trace levels of cyanide and detoxify the affected tissues. Some individuals may be more at risk than others are, based on the composition of their mitochondrial DNA and variations in the...

Time Spent in Hospital

Many cataract operations are now done under local anaesthesia as day cases. General anaesthesia is preferred in younger patients and especially where there is a risk of straining or moving during the procedure as, for example, when the patient is deaf. An overnight stay is needed after a general anaesthetic in many cases. The elderly patient living alone with no relatives is also usually kept overnight in hospital but the trend is towards more and more day-

Neurosurgery of the Visual Pathway

The visual pathways take an extraordinary and extensive intraorbital and intracranial course from the globe to the visual cortex within the occipital lobes. Hence, a large number of orbital and intracranial pathologies interfere with the optic pathways. The diagnosis and treatment of these pathologies demands an interdisciplinary team with ophthalmologists, neuroradiologists, neurosurgeons, and radiation therapists. The management algorithm takes into consideration presenting signs and symptoms, as well as ophthalmologic and imaging findings. It requires a multimodal treatment protocol depending on the biological nature and location of the pathology.

Spasm of the Near Reflex

Spasms of accommodation and convergence are usually functional in nature, but are occasionally the result of a severe head injury or part of a dorsal midbrain syndrome. A highly variable (moment-to-moment) esotropia is accompanied by pupillary miosis and accommodative myopia. When binocular horizontal pursuit movements are tested, the adducting eye takes up fixation in either direction. This pseudo-abducens palsy is usually enhanced during cover uncover testing ( Fig. 10.8). The spasms can last for a few seconds or for several hours. In addition to the blurring and diplopia, headache is associated with the longer lasting spasms.

Ocular Muscle Imbalance

Mild latent squints can sometimes go undetected until a period of stress or perhaps excessive reading precipitates symptoms of eyestrain and headache. The effort to maintain both eyes in line causes the symptoms. The latent deviation could be inward or outward but because most people's eyes tend to assume a slightly divergent position when completely at rest, a degree of latent divergence (exophoria) is almost the rule and of no significance. Vertical muscle imbalance is less well tolerated and even a slight deviation can cause symptoms. Small but significant degrees of vertical muscle imbalance are seen in otherwise normal individuals who show a marked difference in refractive error between the two eyes or in those with facial asymmetry. The provision of a small prism incorporated into the spectacle lenses of such patients can produce dramatic relief, but we must always remember that the appearance of an ocular muscle imbalance might be the first indication of more serious disease. A...

Heterochromic Iridocyclitis

This type of anterior uveitis presents in 20-40 year olds and is usually unilateral. The vision becomes blurred and the iris becomes depig-mented. The eye usually remains white, the inflammatory reaction is low grade and chronic posterior synechiae do not develop. The inflammation does not usually respond at all to treatment. Cataracts and chronic glaucoma occur commonly. The condition has been mimicked by denervating the sympathetic supply of the eyes in experimental animals and it seems possible that there might be a neurological cause, unrelated and distinct from other types of uveitis.

Secondary to Vascular Disease in the

This is a common cause of sudden blurring of the vision of one eye in the elderly. The retinal veins can be seen to be dilated and surrounded by haemorrhages. In some cases, recovery is marred by a rise in intraocular pressure, which typically appears approximately three months after the onset of the condition. The prompt appearance of this painful complication has given it the name of hundred-day glaucoma . This type of glaucoma is usually difficult to control and even surgical measures can prove ineffective. A typical feature is the appearance of a vascular membrane over the anterior surface of the iris and sometimes the angle of the anterior chamber. This vascularised tissue lends a pinkish hue to the iris and is termed rubeosis iridis. Patients with a central retinal vein thrombosis followed by secondary glaucoma have another problem because there is a recognised association between chronic open-angle glaucoma and central retinal vein occlusion....

Long Sight Short Sight

It is useful to distinguish between long-sighted and short-sighted patients as you will see later in this chapter,but straight away we come across a problem with terminology. Think of the short-sighted old man who cannot see to read without glasses and, at the same time, the short-sighted young lady who cannot see clearly in the distance. The term short sight is used in these instances unwittingly by the layman to mean two different situations either it can mean presbyopia (caused by diminished focusing power with ageing, as in the case of the old man) or it can mean myopia (caused by a larger eyeball, as in the case of the young lady). Leaving aside presbyopia for the time being, we need to realise that the myopic person has physically larger than normal eyes, with an anteroposterior diameter of more than 24 mm, and, by contrast, the hypermetropic (or longsighted person) person has smaller than usual eyes, with an anteroposterior diameter of less than 24 mm. To obtain a clear image,...

Neuroradiologic Imaging

It is the intended purpose of this chapter to provide the practicing ophthalmologist with an understanding of the indications for neuroradiologic procedures, and to illustrate the various imaging methods with typical examples and descriptions of their findings. The use of conventional radiologic imaging in ophthalmology has been reduced to its role in the detection of metallic foreign bodies for a more detailed study of soft tissues, tomographic images have completely replaced them.

Telangiectatic Haemangioma

Also known as the port wine stain or naevus flammeus, this tumour tends to be distributed over the area supplied by one or more of the branches of the fifth cranial nerve and usually remains throughout life as a dark red discolouration in the skin (Figure 15.5). The importance of this particular appearance is its association with secondary glaucoma and hae-mangioma of the meninges. The latter produces calcification and a characteristic X-ray appearance. The combination of lesions is known as the Sturge-Weber syndrome. There can be hypertrophy of the affected area of the face, leading to asymmetry.

Secondary to Abnormalities in the Lens

A cataractous lens can become hypermature and swell up, pushing the iris diaphragm forward and obstructing the angle of the anterior chamber. This is referred to as phacomorphic glaucoma. Removing the lens relieves the situation. Phacolytic glaucoma occurs when a mature cataract causes a type of uveitis. This is thought to result from leakage of lens proteins through the lens capsule. A dislocated or subluxated lens, either the result of trauma or as a congenital abnormality, can be associated with a rise in intraocular pressure.

Types of Corneal Ulcer

A wide range of other bacteria are known to cause corneal ulceration, but, by and large, infections only occur as a secondary problem when the defenses of the cornea are impaired (e.g., by underlying corneal disease, trauma, bullous keratopathy, dry eyes or contact lens wear). Acanthamoeba spp. are a free-living genus of amoeba that has been increasingly associated with keratitis. The keratitis is usually chronic and can follow minor trauma. Contact lens wearers are particularly at risk of this infection. Antiviral agents are usually the first line of treatment. Examples of currently used antiviral agents are idoxuridine, trifluorothymidine, cytarabine and acyclovir. The most effective is acyclovir. Unfortunately, none of these agents is curative, but they are thought to have some effect on acute rather than chronic cases. Early diagnosis and treatment seem to give the best chance of avoiding recurrences. The removal of virus-containing epithelial cells (debridement) is now indicated...

Pars Planitis Intermediate Uveitis

This refers to a low-grade inflammatory response,which is seen in young adults. It affects both eyes in up to 80 of cases, although the severity can be asymmetrical. There is minimal evidence of anterior uveitis and the patient complains of floating spots in front of the vision. Inspection of the fundus reveals vitreous opacities and careful inspection of the peripheral retina shows whitish exudates in the overlying vitreous. A mild-to-moderate peripheral retinal phlebitis can occur. The condition runs a chronic course and occasionally can be complicated by cataract, cystoid macular oedema and tractional retinal detachment. The cause is unknown in the majority of cases, although there is a known association with sarcoidosis.

Measuring for Spectacles

If a patient has not been tested recently for spectacles, not only can the measurement of visual acuity be inaccurate, but the symptoms might be caused by the need for a correct pair of glasses. The measurement, which determines the type of spectacles needed, requires skill developed by practice and the use of the right equipment. The most obvious way to measure someone for a pair of glasses is to try the effect of different lenses and ask the patient whether the letters are seen better with one lens or another. This is known as subjective testing and, by itself, it is not a accurate method because some patients' observations as to the clarity of letters can be unreliable. Furthermore, a healthy young person might see quite clearly with a wide range of lenses simply by exercising the ciliary muscle (i.e., accommodation). Fortunately, the refractive error of the eye can be measured by an objective method and an answer can be reached without consulting the patient. The method entails...

Defects in the Visual Fields

By nerves to the right occipital cortex and the splitting of nerve fibres from each half occurs at the chiasm. For this reason, lesions in the optic nerve anterior to the chiasm tend to cause unilateral defects, whereas those posterior to the chiasm produce hemianopic or quadrantianopic defects (Figure 22.5). Cortical lesions tend to be more congruous. That is to say, the blind areas on each side tend to be similar in shape and size. Cortical lesions also show better preservation of central vision ( macular sparing ). A special type of field defect is seen with expanding pituitary tumours, the resulting pressure on the centre of the chiasm producing a bitemporal defect. Localised defects in the retina produce equivalent localised defects in the visual field on the affected side. Defects because of ocular disease are relatively common as, for example, those seen in the elderly with glaucoma. Care must be taken to interpret field defects with this possibility in mind. Notice from the...

The Abnormally Constricted Pupil

Glaucoma and the constricted pupils of the morphine addict are well known if not so commonly seen. When a constricted pupil on one side is observed it is important to note the position of the eyelids. A slight degree of associated ptosis indicates the possibility of Horner's syndrome. The total syndrome comprises miosis, narrowing of the palpebral fissure because of paralysis of the smooth muscle in the eyelids (Muller's muscle), loss of sweating over the affected side of the forehead, a slight reduction of the intraocular pressure and enophthalmus (sunken globe). Horner's syndrome can be caused by a wide diversity of lesions anywhere along the sympathetic pathway. While a Pancoast's apical lung tumour is classically associated with Horner's syndrome, it is quite often noted in the elderly as an isolated finding and investigation fails to reveal a cause. The Argyll Robertson (AR) pupil is a rare but famous example of the miosed pupil, which responds to accommodation but not to direct...

How to Use the Ophthalmoscope

Before the middle of the nineteenth century, nobody had seen the inside of a living eye and much of the science of medical ophthalmology was unknown. In 1851, Hermann von Helmholtz introduced his ophthalmoscope and it rapidly became used in clinics dealing with ophthalmo-logical problems. The task of von Helmholtz was to devise a way of looking through the black pupil and, at the same time, illuminate the interior of the globe. He solved the problem by ophthalmoscope adjusted so that fundus detail becomes visible. It is best to look for the optic disc first, remembering its position nasal to the posterior pole and slightly above the horizontal meridian. The patient should be asked to look straight ahead at this point. The important points to note about the disc are the clarity of the margins, the colour, the nature of the central cup, the vessel entry and the presence or absence of haemorrhages. Once the disc has been examined carefully, the vessels from the disc can be followed. For...

Structural Abnormalities of the Globe

There are many different developmental abnormalities of the globe but most of these are fortunately rare. Coloboma refers to a failure of fusion of the foetal cleft of the optic cup in the embryo. Coloboma of the iris is seen as a keyhole-shaped pupil and the defect can extend into the choroid, so that the vision might be impaired. Inspection of the fundus reveals an oval white area extending inferiorly from the optic disc. Children can be born without an eye (anophthalmos) or with an abnormally small eye (microphthalmos). It is always important to find out the full extent of this type of abnormality and if the mother has noticed something amiss in the child's eye, referral to a paediatric ophthalmologist is required without delay. Often a careful discussion of the prognosis with both parents is needed.

How to Examine a Childs

The general examination of the eye has been considered already, but in the case of the child, certain aspects require special consideration. Before the age of three or four years, it might not be possible to obtain an accurate measure of the visual acuity, but certain other methods that attempt to measure fixation are available. The rolling ball test measures the ability of the child to follow the movement of a series of white balls graded into different sizes. Another test makes use of optokinetic nystagmus, which can be induced by making the child face moving vertical stripes on a rotating drum. The size of the stripes is then reduced until no movement of the eyes is observed. In practice, a careful examination of the child's ability to fix a light, and especially the speed of fixation, is helpful. The behaviour of the child can also be a helpful guide, for example the response to a smile or the recognition of a face. Sometimes grossly impaired vision in infancy is overlooked or...

Preface to Third Edition

It is a pleasure to welcome two new authors who have contributed to the third edition of Common Eye Diseases Peter Galloway and Andrew Browning. Six years have passed since the last edition but even in this relatively short time there have been significant advances in the diagnosis and management of eye disease and an update has become necessary. Each author has taken a block of chapters for revision and, where needed, illustrations have been added or removed. Apart from the four main authors, I am indebted to Mr Roland Ling for his invaluable work on the chapter on the retina and once again to Professor Rubinstein for his help with the chapter on contact lenses. The original aims of the book have not been changed. It remains as a textbook for medical students and those starting a career in ophthalmology, but also for those in primary care who are likely to deal with eye problems, including nurses, optometrists and general practitioners.

Drops That Constrict the Pupil

In the past, meiotics have been widely used for the treatment of chronic open-angle glaucoma. Pilocarpine is available in 1 , 2 , 3 or 4 solutions. Although it is effective in reducing the intra-ocular pressure, the side effects of dimming of vision and accommodation spasm can be disabling and mean that this treatment has largely been superceded. Pilocarpine is still used in the treatment of acute glaucoma attacks

Allergic Conjunctivitis

Keratoconjunctivitis have a higher risk than normal for the development of herpes simplex keratitis the condition is also associated with the corneal dystrophy known as keratoconus or conical cornea. They are likely to develop skin infections and chronic eyelid infection by staphylococcus. The recurrent itch and irritation (in the absence of infection) is relieved by applying local steroid drops, but in view of the long-term nature of the condition, these should be avoided if possible because of their side effects. (Local steroids can cause glaucoma in predisposed individuals and aggravate herpes simplex keratitis.)

Optic Atrophy after Papilledema Definition

The pathogenic mechanism is not well understood, but ischemia is thought to play an important role. The time needed to develop this complication is variable and is not predictable in individual cases. The transient obscurations of vision often associated with papilledema seem to be unrelated to the risk of atrophy. The visual impairment can begin acutely or subacutely, often with arcuate visual field defects that are very similar to those in patients with chronic open-angle glaucoma, and as is the case with glaucoma, the central-most portions of the visual field are initially spared. The process, once begun, can seem impossible to stop, resulting in total optic atrophy and blindness. Patients with chronic papilledema need to be monitored by an experienced ophthalmologist. Papillede-ma that threatens in this manner (i.e., moderate to marked levels of papilledema that last longer than a few weeks) must be brought under control, either by shunting procedures or...

How the Normal Features Differ from Those in an Adult

At birth the eye is large, reaching adult size at about the age of two years. One might expect that before the eye reaches its adult size, it would be long-sighted, being too small to allow parallel rays of light to be brought to a focus on the retina. In actual fact, the immature lens is more globular and thus compensates for this by its greater converging power. None the less, more than three-quarters of children aged under four years are slightly hypermetropic. The slight change of refractive error that occurs as they grow compares with the more dramatic change in axial length from 18 mm at birth to 24 mm in the adult. The slight degree of hypermetropia seen in childhood tends to disappear in adolescence. Myopia is uncommon in infancy but tends to appear between the ages of six and nine years and gradually increases over subsequent years. The rate of increase of myopia is maximal during the growing years and this can often be a cause of parental concern. atrophic. The foveal light...

Screening of Childrens Eyes

In an ideal world, all children's eyes would be examined at birth by a specialist and again at six months to exclude congenital abnormalities and amblyopia. This is rarely achieved, although most children in the UK are examined by a nonspe-cialist at these points. Most children are also screened routinely in school at the age of six years, and any with suspected poor vision are referred for more detailed examination. A further examination is often conducted at the age of nine or ten years and again in the early teens. The commonest defect to be found is refractive error,that is simply a need for glasses without any other problem. The ophthalmological screening is usually performed by a health visitor in the preschool years and a school nurse for older children. Screening tends to include measurement of visual acuity alone but checking any available family history of eye problems would be helpful. When there is a difference in the visual acuity of each eye, the screener should suspect...

Chronic Conjunctivitis

This is a common cause of the red eye and almost a daily problem in nonspecialised ophthalmic practice. If we consider that the conjunctiva is a mucous membrane that is exposed daily to the elements, it is perhaps not surprising that after many years it tends to become chronically inflamed and irritable. The frequency and nuisance value of the symptoms are reflected in the large across-the-counter sales of various eyewashes and solutions aimed at relieving eyestrain or tired eyes . The symptoms of chronic conjunctivitis are, therefore, redness and irritation of the eyes, with a minimal degree of discharge and sticking of the lids. If there is an allergic background, itching might also be a main feature. The chronically inflamed conjunctiva accumulates minute particles of calcium salts within the mucous glands. These conjunc-tival concretions are shed from time to time,pro-ducing a feeling of grittiness. When confronted with such a patient, there are a number of key Foreign body...

Preface to Second Edition

Like the first edition, this textbook is intended primarily for medical students, but it is also aimed at all those involved in the primary care of eye disease, including general practitioners, nurses and optometrists. The need for the primary care practitioner to be well informed about common eye conditions is even more important today than when the first edition was produced. A recent survey from North London has shown that 30 of a sample of the population aged 65 and over are visually impaired in both eyes and a large proportion of those with treatable eye conditions were not in touch with eye services. It is clear that better strategies for managing problems of eyesight need to be set up. One obvious strategy is the improved education of those conducting primary care and it is hoped that this book will contribute to this. For this second edition, I am grateful for the help of my coauthor Winfried Amoaku, whose personal experience in teaching medical students here in Nottingham has...

Subarachnoid Damage to the Oculomotor Nerve

From the ventral midbrain, through the interpeduncular fossa and to its entry into the cavernous sinus, the third nerve lies in the subarachnoid space, where it is exposed to hemorrhages from aneurysms arising from the supracli-noid carotid artery, mostly at the exit of the posterior communicating artery. Rupture of such an aneurysm produces paralysis of the third nerve, but also the dramatic symptoms of acute subarachnoid bleeds, including abrupt headache of the worst sort, reduced levels of consciousness up to complete coma, and pronounced meningismus. The ophthalmologist will not be confronted by this syndrome in his her own office. In about one third of cases the course is more gradual, beginning with an incomplete internal and external oculomotor nerve paralysis, which precedes onset of extreme levels of head pain referred to the orbital apex. The ocular presentation may lead the patient to consult the ophthalmologist, who should then immediately arrange for emergent...

Oculomotor Pareses in Children

Acquired oculomotor pareses in childhood are mostly traumatic, the consequence of frequent migraine episodes, associated with tumors, or in the context of acute meningitis. Aneurysms as a cause of oculomotor paresis are a rarity in children. An acquired, nontraumatic paresis in a child requires an MRI study with contrast enhancement. If meningitis is suspected, a lumbar puncture is indicated. Depending on the child's age, evaluation to rule out or treat amblyopia in the affected eye is necessary

Hereditary Disorders of Neuro Ophthalmic Relevance

Hereditary disorders of importance for neuro-ophthalmology include genetically inherited disorders of the posterior segment and afferent visual pathway that characteristically present as visual field defects, visual acuity loss, strabismus, or even complete blindness. These disorders have significant social and economic importance with lifelong consequences for the afflicted patient. The prevalence of inherited retinal disorders is approximately 20 cases per 100,000 people. Lens filters, for protection from higher levels of light and improvement of contrast sensitivity, are a rational option that can be of help in the management of some hereditary retinal diseases. Additionally, cataract extraction at an appropriate time and the use of magnifying reading lenses might improve visual acuity in some cases.

Functional Visual Loss and Malingering

Demonstrable Organic Disease Examples

Malingering is an intentionally deceptive mimicry of a nonexistent disorder, and augmentation is an intentionally exaggerated account of an existing disorder. Functional visual loss is a subjectively described visual disorder without an objectively observed abnormality. It is an unconscious, often subconscious, simulation of a nonexistent disease. (Synonyms include psychogenic visual loss, conversion, and hysterical visual loss). The related group of psychogenic ocular disorders includes functional disease, psychosomatic disease, and artificial eye diseases. Psychosomatic eye disease is initiated by a psychically triggered (or heavily influenced) organic disease with demonstrable pathological findings, as for example, in some reported cases of glaucoma, uveitis, or central serous retinopathy. Artificial eye diseases arise by self-inflicted trauma (autoaggression) and have demonstrable pathological findings during the eye examination. This type is usually associated with psychoses or...

Incidence and Causes of Blindness

In England and Wales, the prevalence of blindness in 1980 for children under five years was 9 100,000. This figure increased to 2324 100,000 for adults over 75 years. In the western world, blindness in children is largely because of inherited genetic disease and birth trauma. In adults aged 20-60 years, the major causes are diseases of the retina, including diabetic retinopathy and optic atrophy. Over the age of 60 years, macular degeneration, glaucoma and cataract are the important problems. In Africa and Asia, the causes of blindness are rather different many children become blind from corneal scarring associated with vitamin A deficiency and measles. Cataract is the most important cause in adults but in certain areas, for example southern Sudan, onchocerciasis and trachoma are still a serious problem.

Visual Loss of Uncertain Origin Diagnostic Strategies

The practicing ophthalmologist faces a common challenge on a daily basis A patient's vision is worse than was expected, based on the appearances of the initial examination. Usually, a renewed and more careful examination explains the discrepancy. Often, however, additional examination finds nothing to explain the conflicting findings. Time is limited, and one is tempted to refer the patient to a neurologist or another ophthalmic service. The diagnostic modalities available at the next site often lead to an unguided attempt at diagnosis when it is felt that some sort of explanation for the visual loss must be found. This scenario can be both expensive and dangerous, subjecting the patient to a random wandering through neurodiagnostic procedures. At the end of this process, the patient is unsatisfied and anxiety ridden and returns to the ophthalmologist or seeks the counsel of other physicians or even alternative medicine practitioners. If the ophthalmologist wishes to find the correct...

Historical Background

In 1847, the English mathematician and inventor Charles Babbage showed a distinguished ophthalmologist his device for examining the inside of the eye, but unfortunately this was never exploited and it was not until 1851 that Hermann von Helmholtz published his classic description of his instrument, the ophthalmoscope. He developed the idea from his knowledge of optics and the fact that he had previously demonstrated the red reflex to medical students with a not dissimilar instrument. In principle, he had, for the purposes of his demonstration, looked through a hole in a small mirror, which reflected light from a lamp into the subject's eye. This produced the red reflex in the pupil well known to photographers and night drivers and no doubt this fascinated medical students at that time. Von Helmholtz worked out that a similar device could be used to inspect the inside of the eye. According to correspondence of the time, it took him about a week to learn the technique of examining in...

Proliferative Retinopathy

Proliferative diabetic retinopathy is characterised by the development of new blood vessels (neovascularisation) on the optic nerve head or the retina (Figure 21.4). These occur as a response to retinal ischaemia. These new vessels can appear as small tufts, which ramify irregularly. They might be flat initially but enlarge and move forward into the vitreous cavity as they grow. Once the new vessels form and grow, there is increased risk of an acute pre retinal or vitreous haemorrhage. This is a significant threat to vision because the vitreous haemorrhages can become recurrent or dense, preventing any meaningful examination and treatment. Retinal fibrosis, traction retinal detachment and neovascular glaucoma can occur at a later stage.

Findings on Slitlamp Microscopy

A detailed view of any cataract can be obtained with the slit-lamp. By adjusting the angle and size of the slit beam, various optical sections of the lens can be examined, revealing the exact morphology of the cataract. The presence of small vesicles under the anterior lens capsule can be seen as an early sign of senile cataract. Cataracts secondary to uveitis or to drugs might first appear as an opacity in the posterior subcapsular region. For optical reasons, an opacity in this region tends to interfere with reading vision at an early stage. Opacities in the lens can appear in a wide range of curious shapes and sizes, and earlier in the last century there was a vogue for classifying them with Latin names, which are now largely forgotten. Such a classification is of some help in deciding the cause of the cataract, although it can sometimes be misleading. Congenital cataracts are usually quite easily identified by their morphology, as are some traumatic cataracts. When a unilateral...

Abnormalities of Refraction

Nowadays children whose vision is impaired because they need a pair of glasses are usually discovered by routine school testing of their visual acuity. They might also present to the doctor because the parents have noticed them screwing up their eyes or blinking excessively when doing their homework. Some children can tolerate quite high degrees of hypermetropia without losing visual acuity simply by exercising their accommodation, and unless there appears to be a risk of amblyopia or squint, glasses might not be needed. By contrast, even slight degrees of myopia, if both eyes are affected, can interfere with school work. Myopia does not usually appear until between the ages of five and 14 years, and most commonly at about the age of 11.

Determination of the Angle of Strabismus

Subjectively, the angle of deviation can usually be determined more quickly and reliably by having the patient report the locations and separations between the doubled images. Prerequisites for this method are normal retinal correspondence, adequate visual acuity, and patient cooperation. For patients with spontaneous diplopia the motil-ity deficit can be estimated without additional equipment during fixation on an object that has sufficient contrast with its background. For example, consider uncrossed di-plopia at the primary position (the image from the right eye is seen to the right, while the image from the left eye is seen to the left) that increases in right gaze and decreases in left gaze. This means that gaze to the right produces an increasing esodeviation. To judge cyclodeviations the examiner must provide a straight line (a yardstick, for example) that the patient can use to describe the angle of tilt. The perceived image rotation is the opposite of the eye's rotation....

Ingrowing Eyelashes Trichiasis

Lashes are found to be the cause of the patient's discomfort, it is common practice simply to epilate them with epilating forceps. This produces instant relief, but often the relief is shortlived because the lashes regrow. At this stage, the best treatment is to destroy the lash roots by electrolysis before epilation. Needless to say, before removing lashes it is essential to be familiar with the normal position of the lash line and to realise, for example, that hairs are normally present on the caruncle. When the lash line is grossly distorted by injury or disease, the rubbing of the lashes on the cornea can be prevented by fitting a protective contact lens or, if this measure proves impractical, it might be necessary to transpose or excise the lashes and their roots.

How to Find Out What a Patient Can

One obvious way to measure sight is to ask the patient to identify letters that are graded in size. This is the basis of the standard Snellen test for visual acuity (Figure 3.1). This test only measures the function of a small area of retina at the posterior pole of the eye called the macula. If we stare fixedly at an object, for example a picture on the wall, and attempt to keep our eyes as still as possible, it soon becomes apparent that we can only appreciate detail in a small part of the centre of the field of vision. Everything around us is ill-defined and yet we can detect the slightest twitch of a finger from the corner of our eyes. The macula region is specialised to detect fine detail, whereas the whole peripheral retina is concerned with the detection of shape and movement. In order to see, we use the peripheral retina to help us scan the field of view. The peripheral retina can be considered as equivalent to the television cameraman who moves the camera around to the...

Dural Carotid Cavernous Fistula

Dural carotid-cavernous fistulas arise spontaneously and primarily in elderly women. Dural branches of the internal or external carotid are equally involved, and fistulas often arise spontaneously from both sources. The resulting venous congestion causes an ectasia of the orbital and conjunctival veins that are clearly differentiable from inflammatory hyperemia (large, rope-like conjunctival vessels that contrast with white scleral tissue), as well as chemosis with lid swelling, exophthalmos, retinal vascular dilatation with intraretinal hemorrhages, and elevated intraocular pressure. The latter feature is caused by the marked elevation in episcleral venous pressure that is transmitted directly to the anterior chamber. The elevated pressure in the cavernous sinus causes damage to the third, fourth, and sixth cranial nerves, resulting in diplopia. Frequently, patients hear a pulse-synchronous bruit when background noise is diminished, usually when retiring for the evening, and often...

Capillary Haemangioma of the Newborn Strawberry Naevus

This is usually seen before the age of six months, and nearly all examples regress spontaneously, usually in few months and by the age of five years. Tumours appear as red, slightly raised marks on the skin. Even extensive tumours of this kind can show a dramatic improvement over several years and conservative management is usually indicated unless the tumour is associated with a fold of skin that occludes the eye, causing amblyopia. Larger tumours can produce orbital enlargement. If treatment is required, intralesional steroid injections have proved beneficial.

Pathogenesis and Natural History

Primary open-angle glaucoma is nearly always bilateral, but often the disease begins in one eye, the other eye not becoming involved immediately. It is important to realise that the progress of chronic glaucoma can be arrested by treatment, but unfortunately, many ophthalmologists experience the natural history of the disease by seeing neglected cases.

Transient Visual Loss

By transient visual loss we mean a drop in visual acuity or a loss of visual field, analogous to the transient ischemic attacks (TIAs) of neurological disease that last no longer than 24 h. This chapter does not discuss transient visual loss for which primary ophthalmic disorders are evident, such as intermittent angle closure glaucoma, vitreous clouding, retinal venous stasis, or the transient obscurations found in papilledema. Patients complaining of transient loss of vision frequently cause clinicians a great deal of worry, since the nature of their problem is often obscure. They may describe dramatic symptoms of visual loss without there being even a trace of objectively verifiable pathology. This can naturally lead the physician to consider a wide range of disorders, leading to a complex series of diagnostic tests, often without significant findings. Since a transient visual disturbance can be the harbinger of a retinal arterial occlusion, or even a stroke, the physician does not...

Findings of Ophthalmoscopy

The best way of picking up a cataract in its early stages is to view the pupil through the ophthalmoscope from a distance of about 50 cm. In this way, the red reflex is clearly seen. The red reflex is simply the reflection of light from the fundus and it is viewed in exactly the same manner that one might view a cat's eyes in the headlamps of one's car or the eyes of one's friends in an ill-judged flash photograph. In fact, such a flash photo could well show up an early cataract if an elderly relative were included in the photograph. When using the ophthalmoscope, the opacities in the lens are often seen as black spokes against the red reflex (Figure 11.2). It is important to focus one's eyes onto the plane of the patient's pupil if the cataract is to be well seen, and it is preferable to dilate the pupil beforehand or at least examine in a darkened room. Typical age-related lens opacities are wedge shaped, pointing towards the centre of the pupil. At the same time, the central...

Treatable Causes of Failing Vision

Nobody can deny that the practice of ophthalmology is highly effective. Many eye diseases can be cured or arrested, and it is possible to restore the sight fully from total blindness. Many of the commoner causes of blindness, especially in the third world, are treatable. The most important treatable cause of visual failure in the UK is cataract, and, of course, no patient should be allowed to go blind from this cause, although this does occasionally happen (Figure 8.1). Retinal detachment is less common than cataract but it provides a situation where the sight could be lost completely and then be fully restored. For the best results, surgery must be carried out as soon as possible, before the retina becomes degenerate, whereas delay before cataract surgery does not usually affect the outcome of the operation. Acute glaucoma is another instance where the sight could be lost but restored by prompt treatment. The treatment of chronic glaucoma has less impression on the patient because it...

Central Disturbances of Vision

A central disturbance of vision should be suspected when an ophthalmic examination finds normal visual acuity and normal appearing anterior and posterior segments in both eyes, in the setting of a plausible complaint of difficulty with recognition of visual images. The human visual system does not terminate at the primary visual cortex. On the contrary, central processing of images begins at the striate cortex. Given the well-vascularized tissue of the poststriate visual cortex, damage to vision in these regions is compar