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E.A. Polska, A. Doelemeyer, J.J. Kremers, A. Unterhuber, L. Schmetterer, W. Drexler, G.N. Lambrou; Morphological and Functional Assessment of Early Changes in the Macular Region and the Optic Nerve Head of Ocular Hypertensive Non–Human Primates . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3512.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate early changes in retinal morphology and visual function in eyes of cynomolgous monkeys after unilateral induction of ocular hypertension (OHT). Methods: Experimental OHT was induced unilaterally in 6 cynomolgous monkeys by laser photocoagulation of the trabeculum. Three baseline experiments were performed and study days were scheduled every 2–3 weeks over 12 months after surgery. The protocol for each study day included intraocular pressure (IOP), ultrahigh–resolution optical coherence tomography (uhr–OCT), scanning laser polarimetry (GDx), confocal scanning laser tomography (HRT) and multifocal electroretinography (mfERG) measurements in both eyes. Horizontal and vertical cross–sectional images of the macular region and the optic nerve head (ONH) as well as circular scans with increasing diameter centered at the ONH were performed with the uhr–OCT system to characterize morphological alterations and to calculate retinal and intra–retinal layer thickness. Nerve fiber layer (NFL) thickness maps were generated using GDx with variable cornea compensation. Focal image sequences of the ONH were acquired using HRT. Visual function was assessed using mfERG. Results: OHT developed differently in the six monkeys. Despite the differences in duration and level of IOP elevation, all monkeys showed changes in ONH topography as evidenced by HRT and uhr–OCT measurements. In 2 monkeys stable IOP elevation by 20–35 mmHg led to an almost complete loss of NFL and visual function within 6 to 8 weeks post laser surgery. Surprisingly, 1 monkey did not show any loss of NFL or visual function, although displaying a stable increase in IOP. Three animals showed only sporadic and/or a mild increase in IOP of 10–15 mmHg. Morphological changes could also be evidenced with the employed techniques in these animals, but to a much lesser extent. Over the whole time course the morphological and functional measurements correlated well for the individual eyes. Conclusions: The ocular hypertensive non–human primate model of glaucoma exhibits morphological and functional changes very early, 2 to 3 weeks after induction. All morphological measurements taken correlate well. Due to the rapid time–course of changes more frequent measurements are necessary to allow conclusions about the sequence of events in this model.
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