Comparison of alloplast materials in experimental extraocular muscle surgery

Extraocular muscles may be recessed using implants as spacer material. Silicone retinal band is an example of a spacer used to elongate the superior oblique (SO) tendon in Brown's syndrome and SO overaction; however, complications such as extrusion, scarring and restriction due to the implant have been reported. The purpose of our study was to evaluate and compare fibroblastic and inflammatory reactions to different alloplast materials in a rabbit model.

Twenty-three rabbit eyes underwent superior rectus (SR) expander surgery, and 9 eyes SR recession surgery. SR expander surgery was performed using either silicone retinal band (240 style; 6 eyes), polytetrafluoroethylene (Gore-Tex; 10 eyes) or porous polyethylene (Medpor; 7 eyes). Twenty eyes were enucleated at 4 weeks and 12 eyes at 8 weeks and examined by light microscopy. The expression of basic fibroblast growth factor (bFGF) was evaluated by immunohistochemical analysis.

All alloplast materials induced more inflammatory response compared to control eyes (p < 0.05). Medpor induced a markedly stronger inflammatory response than silicone and Gore-Tex (p < 0.05). Gore-Tex and silicone induced similar inflammatory responses. Gore-Tex implants yielded a slightly higher bFGF expression than silicone or Medpor implants (p = 0.07).

Polytetrafluoroethylene (Gore-Tex) was found to be similar to silicone in its biocompatibility when used as spacer material in extraocular muscle tendon expander surgery. The high bFGF expression observed in Gore-Tex-implanted eyes suggests porous polymers may promote tissue ingrowth into the implant.