Synthetic scleral reinforcement materials: I. Development and in vivo tissue biocompatibility response

The surgical treatment of pathological myopia involves the placement of a band cut from donor sclera around the back of the globe to provide support and to prevent elongation that leads to retinal detachment and blindness. In the search for a synthetic material that would overcome the disadvantages of the donor tissue band, we tested 11 types of bands made from 14 polymers in rabbit eyes. Bands were cut from porous and solid materials, as well as porous materials coated with solids and solid materials with porous patches affixed to the posterior surface. Criteria for suitability and biocompatibility included ease of placement and suturing, stable positioning, and absence of long-term tissue response on a cellular level. Testing included evaluation by the surgeons performing the implantations, measurement of the distance between the band and the globe, determination of fibrous capsule thickness and amount of collagen deposition, and enumeration of macrophages accumulated at the band/capsule interface. Based on the results of these studies, two of the porous materials (expanded polytetrafluoroethylene and porous polyurethane fabric) and two of the composite materials (porous polyurethane fabric coated with polyacrylonitrile and silicone with microvilli cut into the posterior surface) were selected for further study.