Effects of Argon Laser Iridotomy on the Corneal Endothelium of Pigmented Rabbit Eyes

Abstract

PurposeIn Asian countries, laser iridotomy for the treatment of angle-closure glaucoma is a common cause of bullous keratopathy, which may be associated with a shallow anterior chamber and dark iris pigmentation in Asians. Several cases of corneal decompensation after argon laser iridotomy have been reported. In the present study, we evaluated the harmful effects of argon laser iridotomy on the corneal endothelium.MethodsArgon laser iridotomy was performed on the right eyes of pigmented rabbits. Changes in corneal thickness and endothelial cell density after laser iridotomy were evaluated. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was performed for assessment of corneal endothelial cell apoptosis. Combined staining with alizarin red and trypan blue, as well as a live/dead cell assay, were performed for evaluation of damage to the corneal endothelium induced by laser iridotomy.ResultsCorneal thickness did not change immediately after laser iridotomy; however, a significant increase was observed 24 hours after iridotomy (p = 0.001). The endothelial cell density of laser-treated eyes four days after laser iridotomy was significantly decreased compared with control eyes (p < 0.001). TUNEL staining showed many TUNEL-positive cells in the corneal endothelium and corneal stroma. No endothelial trypan blue-stained cell nuclei were observed after laser iridotomy; however, several large endothelial cells with damaged membrane integrity were observed. The live/dead cell assay clearly showed a large number of dead cells stained red in several areas throughout the entire corneal button 24 hours after iridotomy.ConclusionsArgon laser iridotomy induces corneal endothelial cell apoptosis in pigmented rabbit eyes, resulting in decreased endothelial cell density.

Quantitative study of the microvasculature and its endothelial cells in the porcine iris

“…Considering recent evidence from both clinical and experimental studies demonstrating the increased development of nuclear cataract as a consequence of disturbed ocular oxygen gradients caused by vitrectomy (Barbazetto et al, 2004;Holekamp et al, 2005), any iris vascular abnormality would probably affect the oxygen gradients in anterior chamber with pathological consequences. Moreover, there is added potential risk of corneal decompensation after traumatic procedures such as laser iridotomy (Szumny and Szelag, 2014;Wang et al, 2014;Youm et al, 2014).…”