[Fate of artificial lenses: a scanning electron microscopy study]

Thirty one intraocular lenses removed from human eyes 2 months to 30 years after implantation were examined by scanning electron microscopy. Binkhorst 4 loop lenses (12) and 2 loop lenses (6), and Choyce lenses (6) were the most prevalent styles examined. Most of the lenses produced before 1978 were found to have manufacturing defects (mold disalignment, unfinished gate areas, etc.). More recent lenses showed an improvement in the quality of the surface. The lenticular, nonimpinging portion of the lenses made with polymethylmethacrylate did not demonstrate signs of degradation. However the holes in the edges of the lenses were rough and poorly finished with obvious irregularities. On the other hand, the lens foot of a Choyce lens revealed severe unusual abnormalities: the plastic surface changes may be consistent with degradation. Examination of explanted iris clip lenses showed degradation of the polypropylene loops in two cases: the loops were found to have fractured surfaces.