Preliminary study of hydrophilic hydrogel intraocular lens implants in cats

Soft hydrophilic intraocular lenses (IOLs) made of an aminopolyamide (Duragel) and a hydroxyethylmethylmethacrylate (HEMA) hydrogel polymer were implanted in cats and followed for six weeks. During surgery, a 45-second purposeful contact between the lens surface and the corneal endothelium was made. During the course of the experiment, all implanted eyes maintained clear IOLs and manifested a continuing mild iritis. Scanning electron microscopy of the corneas revealed numerous microvilli but no damage to cell membranes. Scanning electron microscopy of the aminopolyamide IOLs revealed fibroblast growth on the surface. No fibroblast growth was noted on the surface of the HEMA IOLs. These experiments suggest that soft hydrogel IOLs may be better than conventional hydrophobic acrylic IOLs in minimizing endothelial contact damage. However, the observation of corneal microvilli may indicate a mild adverse reaction to the hydrogels, possibly from impurities. Fibroblast growth on the aminopolyamide may also be due to an ocular inflammatory response to the material or impurities. Hydrogel IOLs may be of interest because of their semirigid physical properties and greater safety on contacting the endothelium. However, considerable attention must be given to polymer composition and polymer purification.