Miragel versus silastic used as episcleral implants in rabbits. An experimental and histopathologic comparative study.

Abstract

Tissue reactions to two different biomaterials implanted on the sclera of rabbit eyes, a silicone implant (Silastic; Dow Corning) and a hydrogel (Miragel; Mira Inc.), were evaluated. Both materials were implanted on the scleral surface under the superior rectus to obtain a focal scleral buckling. Histopathologic examination of the 32 eyes was performed with transmission electron microscopy 5 to 8 months after implantation. During the follow-up period, 6 silicone implants were extruded, compared with only one hydrogel implant. Histopathologically, both types of implants were surrounded by a newly formed fibrous capsule. Only the hydrogel implant gave rise to a granulomatous foreign body reaction against its own fragments, however. The main difference between the two types of material was a superficial fragmentation of the hydrogel implants. The reason for this fragmentation is unknown. To our knowledge, this is the first reported case of foreign body giant cell granuloma that developed against a hydrogel implant.