Geometric alterations produced by encircling scleral buckles. Biometric and clinical considerations

The geometric alterations induced in the human globe by the application of an encircling scleral buckle using an in vitro model are described. Both a thin, solid silicone band, and a thicker, oval element produces an encircling buckling effect of predictable height and width. With thin elements, height and width are a linear function of horizontal shortening of the band. A scleral buckle produced by horizontal shortening, irrespective of exoplant material, results in axial lengthening. In contrast, the scleral buckling effect produced by mattress suture invagination of oval or round thicker silicone exoplants results in axial shortening, provided there is no concomitant horizontal shortening. The amount of axial shortening can be increased by using two sutures per quadrant. Since axial lengthening is associated with the potential undesirable complication of radial retinal and scleral folds, and axial shortening is not, buckles created by invagination of broad encircling elements may have certain theoretical advantages.