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 facilitated by lying the patient down and making the incision around the upper part of the cornea where, in the postoperative period, it was protected by the upper eyelid. The use of local anaesthesia was introduced at the end of the nineteenth century and at the same time, attempts were made to suture the cornea back into position. By the beginning of the twentieth century, two methods had evolved for the actual removal of the lens. The safest way was to incise the anterior lens capsule and then wash out or express the opaque nucleus, preserving the posterior lens capsule as a protective wall against the bulging vitreous face. This is known as the extracapsular technique. The intracapsular cataract extraction became the standard operation of choice in most patients over the age of 50 years during the early part of the twentieth century. It involved removing the

Figure 11.3. A typical plastic intraocular implant.There are different designs to suit different surgical techniques. CD

complete lens within its capsule and, by this means, avoided subsequent operations to open up residual opaque posterior capsule.

Perhaps the most dramatic change in cataract surgery has occurred in the latter half of the twentieth century, with the introduction of intraocular acrylic lens implants. Initially, they were mostly employed with intracapsular surgery, but a new technique for extracapsular surgery was then developed and found to be successful with implants. Many different types and designs of intraocular lens have been used over the years. Figure 11.3 shows a commonly used type of lens implant. The trend is now towards smaller incision surgery and the use of foldable or injectable implants, which unfold into position as they are being inserted into the eye. An important and widely used technique is phakoemulsification. Here, the opaque lens nucleus is removed through a complex cannula, which breaks up the lens matter ultrasonically before sucking it from the eye (Figures 11.4,11.5 and 11.6).

Figure 11.4. Type of probe used for phakoextraction of the opaque lens nucleus. 03

Figure 11.4. Type of probe used for phakoextraction of the opaque lens nucleus. 03

Figure. 11.5. Injection of intraocular lens implant through small incision.

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