Early changes in the optic disc in experimental glaucoma

R. Varma, C. F. Burgoyne, Harry A Quigley

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Abstract

Purpose: To determine early changes in the optic disc topography in experimental glaucoma in non-human primates. Methods: The optic discs of cynomolgus monkeys were imaged following the development of laser-induced unilateral experimental glaucoma. Images were acquired and analyzed using the Topcon Imagenet system. Permanent changes in the mean position of the disc (MPD), neural rim area (RA), disc area (DA), rim area-to-disc area ratio (RA/DA) and peripapillary retinal nerve fiber layer height (RNFLH) were measured after lowering the intraocular pressure (IOP) from the elevated level to an IOP of 10 mmHg. This was done to eliminate the effect of IOP-related mechanical compliance of the optic disc. Changes in the optic disc parameters were correlated to the IOP using an analysis of covariance. Results: Eleven eyes of eleven monkeys were studied. The mean follow-up time period after elevation of IOP was 8.2 months .IOP increased from a mean of 15 mmHg to a mean of 28 mmHg following the development of glaucoma. Changes were present in the MPD (p=0.06), RA (p=0.07), and RA/DA (p=0.05) related to the magnitude of IOP elevation and the duration of elevation of IOP. No changes in DA or RNFLH were noted. Every 10 mmHg increase in IOP was related to a 8% decrease in the RA, an 11% decrease in RA/DA and an 21% decrease in MPD. Conclusion: Using this imaging system, early glaucomatous changes can be detected in the optic disc but not in the peripapillary retinal nerve fiber layer height.

Original languageEnglish (US)
JournalInvestigative Ophthalmology and Visual Science
Volume37
Issue number3
Publication statusPublished - Feb 15 1996
Externally publishedYes

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ASJC Scopus subject areas

  • Ophthalmology

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