Use of miotics in squint surgery.

AFIER operations for convergent squint, a comparatively frequent result is that the eyes are straight for distance, but on attempting near vision, the squint reappears. It happens even after a full recession of both medial recti and after the fullest possible spectacle correction. This residual acconmmodational squint proves a great handicap to the full restoration of binocular single vision and any treatment to obviate it would be welcome. The use of atropine in such cases is widespread, with the hope that paralysis of accommodation will reduce convergence. Unfortunately, atropine does not paralyse the will to accommodate. With the eyes atropinized the effort involved in attempting to obtain a clear image (frontal accommodation reflex) can cause a vicious overconvergence. We have often witnessed this unfortunate result when the child is playing with a toy or attempting to read a " get-well-quick" card. Atropine is also unsuitable in such cases because so much of the post-operative orthoptic training, especially bar reading, requires clarity of near vision. It would seem therefore that the opposite effect upon accommodation would be of more use. Would pilocarpine, setting the accommodation for near without any voluntary effort, control this accommodational squint residue? Its use is not new, for Javal (1896) advised a young lady with a squint to use it when attending a wedding. More recently, Abraham (1949, 1952) has described the use of miotics in squints and some of the ill effects of the prolonged use of di-isopropyl fluorophosphonate, including the formation of intra-epithelial cysts of the iris. In our recent investigations, pilocarpine was used as an aid to the postoperative orthoptic training of cases that still showed a convergence for near, although for distance the eyes were straight or almost so. It was found necessary to instil the 1 per cent. drops into both eyes three times a day, and the treatment was started on the second or third day after operation as at no time were the eyes padded. Usually this was done for 4 weeks, followed by drops twice daily for 2 weeks and then once daily for a further 2 weeks. This routine was varied according to the progress of the case. In successful cases, the beneficial effects were quick and dramatic. Cases that showed binocular single vision for near but with a marked tendency to break down to a convergent squint were immediately controlled as were several that were frankly convergent squints for near. The Figure (opposite) shows. this effect of pilocarpine, which assists post-operative orthoptic training. The Table (overleaf) reports the progress of the first nine cases so treated. These results show that success depends on two factors. First, good binocular