Protective effects of viscous solutions in phacoemulsification and traumatic lens implantation

We compared the endothelial protection offered by 1% hyaluronate sodium (Healon), 3% hyaluronate sodium and 4% chondroitin sulfate (Viscoat), and a nonviscous irrigating solution (BSS Plus) during phacoemulsification with and without traumatic intraocular lens implantation. Vital-dye staining and scanning electron microscopy were used to determine acute damage to rabbit corneal endothelium. Cell damage during phacoemulsification alone was not significantly different from that in unoperated controls (12.5%). Cell damage after traumatic lens insertion was significantly greater in the groups treated with BSS Plus (76.2%) and Healon (41.4%) than in either paired Viscoat-treated group (21.1% and 17.4%, respectively). Viscoat (but not Healon) was noted to be adherent to the cornea at the end of the procedure in one third of the cases, indicating that Viscoat remains in the anterior chamber during surgery. We attribute this to chondroitin sulfate's newtonian characteristics, allowing it to maintain viscosity in the face of high flow rates.