Protective Effect of Morin Hydrate on Reactive Oxygen Injury in Rabbit Corneal Epithelium

PURPOSE: Free radicals are responsible for tissue injury in corneal preservation and transplantation. Morin hydrate, a flavonoid from Brazil wood, has been shown to be cytoprotective in several types of cells. The aim of this study was to investigate the effectiveness of morin hydrate on rabbit cornea against damage induced by oxyradicals and nitric oxide. METHODS: The rabbit cornea was studied in modified Ussing chambers to determine the effects of hydrogen peroxide (H2O2) or sodium nitroprusside (SNP) by measuring the bioelectrical properties (short-circuit current (Isc), tissue resistance (Rt) and potential difference (PD)). RESULTS: 1.0 mM H2O2 markedly increased the Isc at the tear side (T-side), but not at stromal side (S-side), suggesting the site of action of H2O2 was the apical membrane (T-side). After pretreatment with morin hydrate (T-side, 1.0 mM), H2O2-induced increase of Isc and PD was markedly reduced. In addition adding morin hydrate with H2O2 simultaneously, the increase of Isc and PD was also markedly reduced. Exposure of cornea to SNP at the T-side increased nitric oxide, and increased the bioelectrical properties (PD and Isc). This effect was attenuated by the treatment with morin hydrate. CONCLUSIONS: This study demonstrated that morin hydrate behaved as a antioxidant. This property of morin hydrate may help prevent protect cornea in preservative solutions from free radical damage.

Diode Laser Ab Externo Sclerostomy in Rabbits

Sclerostomy is preferable full-thickness filtration surgery, if very low pressure are desired or if guard filtration surgery had failed. Laser sclerostomy can be performed in a less invasive manner than standard procedure, so it reduces scar formation and minimizes postoperative complications. The objective of this investigation was to determine the feasibility and parameters of laser sclerostomy using a diode laser. The diode laser with a fiberoptic delivery system is lightweight, portable and utilizes a 100 Volt outlet. Eighteen eyes of pigmented rabbits underwent a diode laser ab externo sclerostomy with energy 2 W, duration 1-2 seconds by applying endolaser probe, 0.5 mm from the limbus. Gross and histopathologic examination were done at 1 hour and 7 days after treatment. A patent fistula with formation of filtering bleb was achieved in all cases. There was a flattening of the filtration bleb at 3.3 postoperative days.