Pterygium, the reddish fleshy triangular growth, with its base at the inner canthus, and its apex spreading to and often over the cornea, requires invariably a small operation for its removal. In most cases it will be found sufficient merely to raise the lax portion over the sclerotic with forceps, and divide it freely, removing a transverse portion. If it has encroached upon the cornea, the portion interfering with vision must be dissected off with great care and removed.
In some cases, however, it has been found that after removal of a large pterygium, a retraction of the caruncle and the semilunar fold is apt to take place, which renders the eyeball unpleasantly prominent. To avoid this the pterygium may be carefully dissected up from its apex to near its base, and then displaced laterally either upwards or downwards, its apex and sides being stitched to a previously prepared site of conjunctiva.
Operation for Convergent Strabismus.—Division of the internal rectus.—Subconjunctival operation.—The spring-wire speculum (C) separating the lids, the surgeon divides the conjunctiva by a pair of scissors in a horizontal line (Fig. xi. A A) from the inner margin of the cornea, a little below its transverse diameter to the caruncle, then snipping through the sub-conjunctival tissue, he passes a blunt hook bent at an obtuse angle under the tendon of the internal rectus, and endeavours by depressing the handle to project the point of the hook at the wound. Then with successive snips of the scissors he divides the tendon on the hook, close to its sclerotic margin. Lest it should not be freely divided, various dips with the hook may be made to catch any stray fibres left untouched; but very great care should be taken not to wound the conjunctiva beyond the first horizontal cut in it. The tendon being divided satisfactorily, the edges of conjunctiva should be replaced, and the eye closed for a few hours.
Fig. xi. [85]
The original operation of Dieffenbach, now rarely practised, consisted in making an incision, b b, across the tendon, then, by cutting the areolar tissue exposing the insertion of the tendon, and dividing it freely; after which the sclerotic in the neighbourhood was to be cleaned and any band of fibres divided. There are risks on the one hand of a most unseemly exophthalmos with divergent squint, and on the other of a retraction of the semilunar fold, so that the sub-conjunctival operation is always preferable.
Operations for Divergent Squint.—This very serious deformity is often the result of the operation for convergent squint, and is associated with a fixed, leering, and prominent eye, and frequently with most annoying double vision.
1. In a simple case of primary divergent strabismus (very rare) it is sufficient simply to divide the external rectus in the manner already described for division of the internal.
2. If secondary to an operation for convergent squint, the indication is to restore the cut internal rectus to a position on the sclerotic a little behind its previous one, as the cause of the divergence is found in a complete detachment of the internal rectus. This is attempted in various ways.
(1.) Jules Guérin carefully divided the conjunctiva over it, and sought for the remains of the internal rectus, freeing it from its attachments. He then passed a thread through the sclerotic on the outer side of the globe, and by pulling on it and fixing it across the nose, rotated the eye inwards, in the hope that the remains of the internal rectus would secure a new attachment.