Encircling silastic 3-mm. band without evacuation of subretinal fluid

In retinal detachment surgery, Chawla (I97I) had excellent results using a 7-mm. encircling silastic band, cauterization of the edges of the tear by cryocautery, and evacuation of the subretinal fluid (Schepens, Okamura, and Brockhurst, I957). He felt that the technique was simpler than scleral dissection and safer than the supramid encircling suture. The present study has the following aims: (i) To describe a simplified technique using an encircling 3-mm. silastic band pressing on the sclera at the equator with cryo-coagulation or minimal effective diathermy of the tear edges but without evacuation of the subretinal fluid. (2) To compare the results of IOO operations using the technique described with the results of IOO operations using segmental buckling of the diathermized or cryo-coagulated sclera opposite the edges of the retinal tear by a 5-mm. diameter silicone rod, also without evacuation of the subretinal fluid (Custodis, 1952). In both series of operations most of the subretinal fluid was absorbed before the operation after 3 days' rest in bed, binocular bandaging, atropine sulphate 2 per cent. drops to the affected eye, and fixation of the head so that the retinal tear was most dependent. In both series, the pressure of the synthetic material on the scleral sensory nerve endings during the early postoperative hours, while ocular tension was relatively high, produced an axon reflex engorgement of uveal capillaries (Duke-Elder and Gloster, I968). The choroidopathy aided in sealing the retinal tear edges. For this reason the ocular tension was not reduced during the operation by evacuation of the subretinal fluid, paracentesis, or giving intravenous mannitol or urea. The technique of the encircling silastic band operation used is as follows: An external canthotomy is performed and a lid speculum applied. The bulbar conjunctiva is cut right round io-mm. from the limbus. The four rectus muscles are exposed in the field of the operation by cutting the inter-rectus fascia. In between the rectus muscles, 13 and 15-mm. from and concentric with the limbus, a mattress supramid suture is passed for 5 mm. each side in half the scleral thickness in each quadrant of the eye (so that the silastic band passes under the supramid loops exactly at the equator, 14-mm. from the limbus). A 3-mm. wide silastic sponge band about 8 cm. long is passed under the four rectus muscles and the supramid mattress suture bridges all round the globe. The ends of the band are left to meet at the upper temporal quadrant of the globe. A double tie without a final knot is placed at the ends of each supramid mattress suture without pressing the band so that the latter can move freely over the sclera when its ends are pulled under the rectus muscles and supramid bridges. The ends of the silastic band are pulled, and while they are stretched indenting the sclera a double tie is made without a final knot. When the band is stretched, it becomes about I 5 mm. in breadth. Patency of the central retinal artery and transparency of the cornea are assured before the final knot is placed on the double tie of the band. The band ends beyond the final knot are then cut off.