Hydrogen Peroxide and Corneal Endothelium

Abstract

Because of recent evidence of low levels of hydrogen peroxide in the aqueous humor, studies were performed to determine levels of corneal endothelial toxicity as well as factors modifying toxicity. Perfusion of cornea endothelial cells for 3 h with varying concentrations of hydrogen peroxide demonstrated a threshold of toxicity at a concentration between 0.3 and 0.5 mM H2O2. The toxic effect resulted in rapid corneal swelling as well as disruption of endothelial cell cytoplasm and organelles. Both the physiologic and anatomic toxic effects of 0.5 mM H2O2 could be blocked with 5400 U/ml catalase. Exposure of corneas to 20 mM H2O2 for 10 min in the presence of EDTA - Fe+3 resulted in an enhancement of corneal swelling rate more rapid than that which resulted from a 10 min exposure to 20 mM H2O2 alone. Neither the presence of ascorbic acid nor the absence of glutathione and adenosine had and effect on the cornea swelling rate which occurred during a 3 h perfusion of endothelium with 0.3 mM H2O2. Chelated iron had no effect on the corneal swelling induced by phototactivation of rose bengal presensitized cornea endothelial cells.

Corneal Endothelial Cell Damage by Free Radicals Associated With Ultrasound Oscillation

“…Some investigators have reported on the effect of the oxidative stress on the corneal endothelium by electron microscopic observations. Injection of hydrogen peroxide into the anterior chamber in vivo can cause swelling of the cytoplasm, disruption of the organelles in the corneal endothelial cells, 30 shrinkage of the cells, and disruption of the intercellular junctions of the Descemet membrane. 31 Riboflavin-UV-A-mediated exposure in vivo can induce chromatin condensation, apoptotic bodies, and shrinkage of endothelial cells.…”

Prevention of posterior capsule opacification through intracapsular hydrogen peroxide or distilled water treatment in human donor tissue

“…However, corneal endothelium is more delicate than corneal epithelium and lacks regenerative capabilities. There is a normal physiological concentration of around 0.5 mM H2O2 in the aqueous humor 34 . Fluctuations of up to 3 fold concentration of H2O2 can be regulated by endogenous catalase 35 .…”

Morphological observations of rat corneal endothelial cells after exposure to ozonated solution

“…Because ozone is a potent oxidative agent and corneal endothelial cells have been shown to be damaged by oxidative stress, prophylactic use of an ozonated solution cannot be rationalized without verifying its safety. [20][21][22][23] An earlier study showed that exposure of corneal endothelial cells to 4 ppm ozonated solution for <10 s was safe, based on a biochemical cell viability assay. 19 The results of the present study support these fi ndings and also suggest that safety is enhanced by the use of AA.…”