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G. Cull, J. Reynaud, C. F. Burgoyne, B. Fortune; Retinal Functional Abnormalities at the Onset of Optic Nerve Head (ONH) Surface Topography Change in Experimental Glaucoma. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5518.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether retinal functional changes are present at the onset of ONH surface topography change in a non-human primate (NHP) model of experimental glaucoma.
12 adult NHPs had 3 or more weekly baseline measurements in both eyes of ONH surface topography (HRT3, Heidelberg Engineering, GmbH), multifocal electroretinography (mfERG, 7F slow-sequence, VERIS, Electro-Diagnostic Imaging, Inc) pattern ERG (PERG, VERIS) and full-field, photopic ERG (UTAS E-3000, LKC Technologies, Inc) prior to laser treatments of the trabecular meshwork in one eye to induce chronic elevation of IOP. Bi-weekly recordings of ONH surface topography and ERG continued on alternating weeks throughout the follow-up period. Onset of ONH surface topography change was defined as the first occurrence when the mean position of the disc (MPD) fell below the 95% confidence limit of each eye’s individual baseline range if confirmed during the next two subsequent imaging sessions. Treated and control eye groups were compared by Wilcoxon non-parametric matched pairs t-test for all ERG parameters recorded during the week of ONH change onset and at the second confirmation.
Specificity of the ONH change criterion was 100% in the group of 12 control eyes. In treated eyes, the average duration between onset of change in ONH surface topography and the second confirmation was 4.6 ± 4.4 weeks. The mfERG high-frequency component amplitude (>85 Hz, RMS) was reduced in treated eyes at both onset (p=0.03) and second confirmation (p=0.005), but there were no significant differences for any of the low frequency components at either time point (p>0.10). The PERG N95:P50 amplitude ratio was reduced in treated eyes at both onset (p=0.04) and second confirmation (p=0.02), but absolute component amplitudes were not statistically different. Similarly, the full-field ERG photopic negative response was reduced in treated eyes relative to the B-wave at both onset (p=0.02) and second confirmation (p=0.02), but absolute component amplitudes were unaffected.
The specific pattern of retinal functional abnormalities observed is indicative of early loss of retinal ganglion cell function and/or glial cell changes at the onset of ONH surface topography change in experimental glaucoma.
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