Abstract
Purpose: :
It has been suggested that chondroitin sulphate (CS) in the anterior chamber could be important in the regulation of aqueous humor outflow, and that an increase in CS levels at the trabecular meshwork plays a role in primary open angle glaucoma. The aim of the present study was to analyze the effect of the administration of CS in the rat anterior chamber on intraocular pressure (IOP), flash electroretinograms (ERGs), flash visual evoked potentials (VEPs), and retinal and optic nerve head morphology.
Methods: :
CS (20 µl, 40% in saline solution) was injected in the rat anterior chamber, whereas the contralateral eye was injected with saline solution. IOP was assessed with a TonoPen XL, ERGs were registered in both eyes of each animal under scotopic conditions with a gold electrode, and flash VEPs were registered with skull-implanted electrodes, while retinal and optic nerve head morphology was examined by optical microscopy.
Results: :
A single injection of CS induced a significant increase of IOP, which lasted for 7 days. When CS was injected once a week, the IOP reached a steady state level that was significantly higher than that of saline-injected eyes, and lasted all along the duration of the study (10 weeks). At 6 weeks of CS administration, a significant reduction of the scotopic ERG a- and b-wave amplitude was observed (p< 0.05). These parameters were further reduced after 10 weeks of treatment with CS (p< 0.01). No differences in the a- and b-waves latencies were observed between both groups. After 6 and 10 weeks of ocular hypertension, a significant decrease in the VEP positive wave P2 amplitude was observed. A significant loss of ganglion cell layer cells and of optic nerve axons was detected in animals that received CS for 10 weeks, as compared with vehicle- injected eyes.
Conclusions: :
The present results indicate that the chronic administration of CS induced significant functional and morphological changes in the retina and optic nerve head, which seem consistent with some features of primary open-angle glaucoma
Keywords: intraocular pressure • outflow: trabecular meshwork • ganglion cells