Enhanced Protective Properties of Visiol® against Experimental Free Radical Damage to the Corneal Endothelium

Abstract

Abstract: : Purpose: To evaluate the protective properties of Visiol^® (2% sodium hyaluronate) vs Healon^® and Viscoat^® on the corneal endothelium in the presence of oxidative stress induced by H₂O₂ at various concentrations. Methods: This was a randomised, masked-observer trial. 12 groups of animals (10 eyes per group). Rabbits were anaesthetised with intra-muscular ketamine chlorhydrate (50mg/kg) and topical 1% tetracaine. A total of 100µl of aqueous humour (AH) was removed from the eye with a precision aspiration pump and a syringe with a 30G needle inserted through the corneoscleral limbus. A 1mm stab limbar paracentesis was done and ophthalmic viscosurgical device (OVD) was introduced into the anterior chamber (AC) until complete filling. After waiting 1min, an I/A cannula was introduced in the AC by a separate valve 20G incision and irrigation-aspiration carried out until complete removal using BSS. A volume of 100µl of H₂O₂ (1mM, 10mM and 100mM) or Lactated Ringer solution (control) was injected through the first paracentesis using the Hamilton syringe. The AC was refilled with BSS and animals were kept under sedation during 5h and then killed with a lethal injection of pentobarbital. The eyes were enucleated and a 9mm central corneal button obtained with a trephine for determination of extent of corneal damage using the Janus Green photometry absorbance technique. Results: No intra-surgical complication was observed in any animal. A dose-dependent damage was observed in the control groups (no OVD). In the experimental groups, all OVDs showed significantly fewer corneal endothelial cell lesions than in the control groups (p<0.05) at all the peroxide concentrations tested. However, Visiol^® showed lower percentage of endothelial cell lesions than Healon^® and Viscoat^® at all peroxide concentrations tested. Conclusions: All OVD efficiently protected the endothelium. Visiol^® showed superior protective ability than Healon^® and Viscoat^® when exposed to free radicals.

Keywords: cornea: endothelium • animal model