The effect of the operation on the lens varies considerably. It may swell up so rapidly that the tension of the eye becomes increased, in which case an evacuation may have to be performed; in other cases, especially in the cases of a patient with high myopia, several needlings may be required before absorption is complete. CAPSULOTOMY Capsulotomy is the division of the opaque capsular membrane left after a cataract has been removed. =Indications.= After a cataract has been removed, either by discission or extraction, an opaque membrane is usually left. This is due to the proliferation of the cells in the anterior capsule of the lens while attempting to lay down new lens fibres. Although the posterior capsule is clear and free from cells, those from the anterior capsule may spread to it and so render it opaque. A fibrinous exudate may also organize and help to thicken the membrane (Fig. 87). For these reasons and also because the soft matter may not have absorbed entirely, it is not advisable to operate too soon after a cataract has been removed. There should be at least six weeks’ interval after an extraction has been performed. A few surgeons operate earlier than this, the idea being that the membrane is then softer and more easily divided. [Illustration: FIG. 87. SECONDARY CATARACT. Opaque capsule after cataract extraction.] Although the operation of discission for after-cataract (capsulotomy) is simple it is not to be undertaken lightly. The patient’s vision should be less than 6/18. In former days the operation was looked upon as attended with as much risk as the extraction, owing to the frequency with which it was followed by inflammation. The reasons for this seem to have been want of proper antiseptic precautions, the passage of the needle through the non-vascular corneal tissue instead of through the conjunctiva, and also the use of a badly made needle, often resulting in prolapse of the vitreous into the wound. A proper discission needle should have sufficient width in its spear-like point to cut a hole large enough to admit the shaft freely; hence needles which have been sharpened several times should be discarded. It need hardly be said that there should be no signs of cyclitis (keratitis punctata) present when the operation is undertaken. =Instruments.= These are the same as for discission, with the addition of a needle with a long cutting edge. [Illustration: FIG. 88. CAPSULOTOMY. _The method of incising the capsule._ The fulcrum of movement of the needle is where the shaft lies in the sclerotic.] [Illustration: FIG. 89. CAPSULOTOMY. _The method of dividing a dense band._ This is done with two needles.]