Purpose: To present selected complications of keratorefractive and phakic intraocular lens (IOL) surgery and a series of IOLs that required explantation because of various postimplantation opacification of the IOL optic.
Methods: Two specimens obtained after keratorefractive surgery, 2 phakic IOLs, and a total of 23 explanted IOLs from cases in which postimplantation opacification of the IOL optic had occurred were studied. These included 6 Bausch and Lomb (B&L) Hydroview H60 M designs, 9 Medical Developmental Research (MDR) SC60B-OUV designs, and 24 IOLs with rigid PMMA optics that had been implanted in the 1980s and early 1990s. Of the latter, 8 required late explantation because of decreased visual acuity. Analyses performed included gross and light microscopic evaluation, histochemical staining, electron microscopy, and energy-dispersive spectroscopy.
Results: We provide examples of 3 postrefractive surgery complications: (1) fungal keratitis after LASIK, (2) post-LASIK corneal decompensation, and (3) cataract formation after implantation of phakic posterior chamber IOLs. Regarding the IOL optic opacities, classifications of 3 types are described: (1) a surface calcification of the B&L Hydroview IOL; (2) diffusion of calcium into the substance of the optic of the hydrophilic "acrylic" SC60B-OUV MDR foldable IOL design, sometimes leading to total opacification of the IOL optic and also its haptics; (3) a distinct pattern of intraoptical opacification with rigid PMMA designs that we term a snowflake degeneration. This term is based on the clinical and pathologic appearance of the individual lesions. Each snowflake lesion represents a focal breakdown of PMMA material as opposed to deposition of exogenous material.
Conclusions: Analysis of complications of refractive surgery represents a new field of ocular pathology. The clinicopathological reports presented here provide an overview of selected complications after refractive surgery. We also help define 3 newly recognized, clinically significant conditions based on postoperative IOL optic opacification. The calcification processes noted on the 2 modern foldable designs studied here (B&L and MDR lenses) need further review by the manufacturers in order to reassess production processes, especially in terms of polymer selection, manufacturing techniques, and other factors required to produce a safe and effective lens. Any lens not meeting today's high standards should not be marketed. The important fact in recognizing the snowflake complication of PMMA IOLs as described here is to alert surgeons about the nature of the lesion so that they will not alarm patients or require extensive and unnecessary testing in trying to determine its pathogenesis. There is no reason why successful explantation cannot be performed in cases where severe visual decrease or loss has occurred.