Comparison of complement activation by silicone intraocular lenses and polymethylmethacrylate intraocular lenses with polypropylene loops.

Silicone intraocular lenses are undergoing clinical investigation for use in the United States. We compared the ability of silicone intraocular lenses to activate the complement system in human sera with that of polymethylmethacrylate intraocular lenses with polypropylene loops using a radioimmunoassay that measures levels of activated complement fragments. Sera incubated with polymethylmethacrylate lenses with polypropylene loops had higher levels of C3a and C5a, but not C4a, than control sera incubated without intraocular lenses. On the other hand, there were no differences in levels of C3a, C4a, and C5a between sera incubated with silicone lenses and control sera. These results suggest that polymethylmethacrylate lenses with polypropylene loops activate the alternative pathway of complement, while silicone lenses do not.