M L J Crawford | PubMed Health

PubMed2004

Glutathione content is altered in Müller cells of monkey eyes with experimental glaucoma.

Extracellular levels of glutamate are thought to be increased in glaucoma and thus contribute to retinal damage. An increase in glutamate concentration or duration in the extracellular retinal space is expected to impact glutathione content in Müller cells since glutamate is the rate-limiting constituent in glutathione synthesis. We have investigated whether glutathione content is changed in retinal Müller cells of monkeys with experimental glaucoma using immunocytochemistry and image analysis. Müller cells in glaucomatous retinas showed significantly greater immunoreactivity (27-57%) for glutathione than those in fellow control retinas, increasing with the duration of elevated intraocular pressure (IOP). This pattern of labeling was prominent in all four monkeys studied. The presence of more glutathione in Müller cells of glaucomatous retinas is consistent with an increase in extracellular glutamate and an increase in transport and metabolism of glutamate.

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PubMed2002

Visual field defects and neural losses from experimental glaucoma.

Glaucoma is a relatively common disease in which the death of retinal ganglion cells causes a progressive loss of sight, often leading to blindness. Typically, the degree of a patient's visual dysfunction is assessed by clinical perimetry, involving subjective measurements of light-sense thresholds across the visual field, but the relationship between visual and neural losses is inexact. Therefore, to better understand of the effects of glaucoma on the visual system, a series of investigations involving psychophysics, electrophysiology, anatomy, and histochemistry were conducted on experimental glaucoma in monkeys. The principal results of the studies showed that, (1) the depth of visual defects with standard clinical perimetry are predicted by a loss of probability summation among retinal detection mechanisms, (2) glaucomatous optic atrophy causes a non-selective reduction of metabolism of neurons in the afferent visual pathway, and (3) objective electrophysiological methods can be as sensitive as standard clinical perimetry in assessing the neural losses from glaucoma. These experimental findings from glaucoma in monkeys provide fundamental data that should be applicable to improving methods for assessing glaucomatous optic neuropathy in patients.

Animals↗