Improved procedure for surface analysis of explanted intraocular lenses by combined light microscopy and scanning electron microscopy.

An improved surface characterization procedure for evaluating explanted intraocular lens (IOL) biocompatibility was developed. The technique combines aqueous hematoxylin-eosin staining for characterizing adherent cells and tissue with subsequent scanning electron microscopy of the same IOL.

Polycarbonate intraocular lenses.

Bisphenol-A polycarbonate has been investigated as an improved polymer for ocular implants, especially for intraocular lenses (IOLs). Polycarbonate properties afford special opportunities for development of tougher, stronger, one-piece IOLs. Autoclave or gamma sterilizability and a higher refractive index may provide additional IOL advantages over polymethylmethacrylate. Implant studies in rabbits have shown polycarbonate IOLs to be well tolerated in the anterior chamber for 2.5 years. Polycarbonate appears promising for new IOLs and other ocular implant applications.

Microstructural matrix-crystal interactions in calcium oxalate monohydrate kidney stones.

The role of the proteinaceous matrix in the formation of calcium oxalate kidney stones is still not well understood. Simple scanning electron microscopy (SEM) has been of somewhat limited value in visualizing the organic and inorganic microstructure due to difficulties in obtaining detailed structural information for cut or fractured surfaces. To help clarify matrix-crystal microstructure, serial sections from 10-20 mm calcium oxalate calculi were partially demineralized with ethylenediamine tetraacetic acid (EDTA) and examined by SEM. Sections etched by EDTA showed a radial crystal structure composed of "microcrystal" subunits. Sections simultaneously EDTA etched and fixed with glutaraldehyde to insolubilize all matrix mucoprotein showed interesting forms of matrix structure: an amorphous sometimes membrane-like material, and a fibrous material that exhibited an apparent affinity for the inorganic crystalline phase. These observations give evidence for a more important etiological and structural role for the matrix than may be suggested by the relatively low matrix concentration in stones (2-6 wt. %).