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Vitreal glutamate concentration in monkeys with experimental glaucoma
Louvenia Carter-Dawson1, Morris L J Crawford, Ronald S Harwerth
1Department of Ophthalmology and Visual Science, University of Texas-Houston Health Science Center, Houston, Texas 77030, USA. louvenia.carter-dawson@uth.tmc.edu
Investigative Ophthalmology & Visual Science
|July 31, 2002
Summary
Vitreal glutamate levels were not elevated in experimental glaucoma models, contradicting theories that high glutamate causes retinal ganglion cell death. This study found no significant difference in glutamate concentrations between healthy and glaucomatous eyes.
Area of Science:
- Ophthalmology
- Neuroscience
- Biochemistry
Background:
- Glaucoma is a leading cause of irreversible blindness.
- Retinal ganglion cell (RGC) death is a hallmark of glaucoma.
- Excitotoxicity from elevated glutamate has been proposed as a mechanism for RGC death.
Purpose of the Study:
- To investigate if elevated vitreal glutamate concentrations contribute to RGC pathophysiology in glaucoma.
- To test the hypothesis that excitotoxic effects of glutamate are involved in glaucoma-induced RGC death.
Main Methods:
- Experimental glaucoma was induced in rhesus monkeys using argon laser trabecular meshwork treatments.
- Posterior vitreous samples were collected from glaucomatous and control eyes.
- Vitreal glutamate levels were quantified using high-pressure liquid chromatography in two independent laboratories.
Main Results:
- Mean vitreal glutamate levels in untreated monkeys were 5.0 +/- 2.0 microM.
- Glaucomatous eyes showed a mean vitreal glutamate concentration of 5.7 +/- 2.6 microM.
- No significant difference in vitreal glutamate levels was observed between glaucomatous and control eyes.
Conclusions:
- Vitreal glutamate concentrations were not elevated in eyes with experimental glaucoma.
- This finding challenges previous reports suggesting toxic glutamate levels contribute to glaucomatous RGC damage.
- The role of vitreal glutamate excitotoxicity in glaucoma pathophysiology requires further investigation.