Scanning electron microscopy was used to study seven Silastic scleral sponges removed between 2 days and 12 years after episcleral implantation. The sponges did not undergo structural changes. Early after implantation, erythrocytes and fibrin and, later, scant fibroblasts were seen on the surface and within the superficial interstices of the sponges. The interstices throughout the sponges contained an amorphous material of unknown composition. These findings support clinical experience that the silicone elastomer of silastic scleral sponges is chemically inert, structurally durable, and well-suited for scleral buckling procedures.