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 limited to the eye itself, but disease elsewhere in the body can often first present as a visual problem. In this context, we must remember what has been the commonest cause of blindness in young people - diabetic retinopathy, as well as the occasional case of severe hypertension. Intracranial causes of visual loss are perhaps less common in general practice and, for this reason, are easily missed. Intracranial tumours can present in an insidious manner, in particular the pituitary adenoma, and the diagnosis might be first suspected by careful plotting of the visual fields. In the case of the elderly patient who complains of visual deterioration in one eye, the ophthalmoscope all too commonly reveals age-related macular degeneration, but it is also common to find that the patient has suffered a thrombosis of the central retinal vein or one of its branches. Unlike the situation with a central retinal artery occlusion, which is less common, some vision is preserved with a central retinal vein thrombosis in spite of the dramatic haemorrhagic fundus appearance. Temporal arteritis is another important vascular cause of visual failure in the elderly.

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. Although age-related macular degeneration is normally seen in the over-60s, the same problem may occur in younger people often with a recognised inheritance pattern. A completely different condition can also affect the macular region of young adults, known as central serous retinopathy. This tends to resolve spontaneously after a few weeks, although treatment by laser coagulation is occasionally needed. Unilateral progressive visual loss in young people can also be caused by posterior uveitis,which is the same as choroiditis. The known causes and management of this condition will be discussed in Chapter 18.

The more common causes of failing vision in a normal-looking eye are summarised in Table 8.1.

Table 8.1. Failing vision in a normal-looking eye. CO

Fundus normal

Fundus abnormal


Refractive error Disuse amblyopia Inherited retinal degeneration Emotional stress


Macular degeneration Posterior uveitis

Young adult

Refractive error Retrobulbar neuritis Intracranial space-occupying lesion Drug toxicity

Diabetic retinopathy Retinal detachment Macular disease Hypertension Posterior uveitis


Homonymous haemianopia

Macular degeneration Central vein thrombosis Chronic glaucoma Cataract

Vitreous haemorrhage Temporal arteritis

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