Abstract
Purpose:
The rapid increases in intraocular pressure (IOP) induce corneal edema in glaucoma patients. We want to investigate the disruptive effects of acute IOP rise on corneal endothelial cells (CECs) in rats.
Methods:
The Sprague Dawley (SD) rats’ anterior chamber of the right eyes was irrigated with Ringer's injection for two hours, and the left eyes were used as controls. IOPs were measured with handheld non-contact tonometer once every twenty minutes. At hour 0, hour 48 and day 7 after irrigation, the corneal edema was observed by silt-lamp microscope, and corneal thickness was measured by Optical coherence tomography (OCT). At the same time, CECs quantity and morphology were assessed by noncontact specular microscopy, and their permeability was determined based on measurements of FITC-dextran tissue accumulation. Apical junctional complex (AJC) integrity was evaluated of zonula occludens-1 (ZO-1), vascular endothelial (VE)-cadherin, filamentous actin (F-actin) and associated microtubules, as well as Na-K-ATPase by immunofluorescent (IF) staining and western blot analysis.
Results:
The average IOP was 83.3±2.5 mmHg (normal range: 11.1±0.8 mmHg) during anterior irrigation and it decreased to normal level immediately after irrigation was finished. Instantly after irrigation, corneal edema became notable, corneal thickness and the permeability to FITC-dextran significantly increased. The structures of AJC (ZO-1and VE-cadherin) and cytoskeleton (F-actin and microtubules) were seriously disrupted by high acute IOP. The expression of Na-K-ATPase obviously decreased. Then CECs quantity and morphology (estimated by DAPI and ZO-1 staining separately) were similar with control eye. Two days after irrigation, CECs quantity dramatically reduced and they lost regular hexagonal morphology. However, corneal edema, thickness and permeability almost recovered to normal level. The structures of AJC and cytoskeleton, expression of Na-K-ATPase were also restored. Seven days later, CECs nearly normalized except for decreased cell density.
Conclusions:
The structure and function of CSCs were disrupted by high acute rise of IOP, which resulted in instantly corneal edema and hereafter the decreased endothelial cells density.