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Scott Ketner, Jr., Carlos Gustavo De Moraes, Christopher C. Teng, Joshua R. Ehrlich, Ali S. Raza, Jeffrey M. Liebmann, Robert Ritch, Donald C. Hood; Beta-Zone Parapapillary Atrophy (ßPPA) and Multifocal Visual Evoked Potentials (mfVEP) in Eyes with Glaucomatous Optic Neuropathy (GON). Invest. Ophthalmol. Vis. Sci. 2011;52(14):5489.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate changes in mfVEP responses due to ßPPA.
Patients with GON with or without standard achromatic perimetry (SAP) abnormalities were referred for mfVEP testing during a 2-year period. Eyes with good quality optic disc stereophotographs and reliable SAP results within 12 months of the mfVEP test were included. Photographs were reviewed by 2 glaucoma specialists and classified based on the presence of ßPPA. Disagreement was adjudicated by a third specialist. Monocular mean latency delays (ms) and amplitudes (SNR) were compared between groups. Age, SAP mean deviation (MD), pattern standard deviation (PSD), and spherical equivalent (SE) were analyzed in the multivariate model. Nested ANOVA and generalized estimated equations were used for comparisons between groups after adjusting for inter-eye associations.
Of the 394 eyes (200 patients), 223 (57%) eyes had ßPPA based on review of photographs. The ßPPA eyes were older (59.6±13.7 vs 56.5±13.7 yr, p=0.02), more myopic (-4.0±3.5 vs -1.3±3.5 D, p<0.01), and had worse SAP (MD: -4.9±5.2 vs -2.6±5.2 dB, p<0.01; PSD: 4.3±2.9 vs 2.5±3.0 dB, p<0.01). By univariate analysis, mean latencies were longer in ßPPA eyes (6.1±5.3 vs 4.0±5.5 ms, p<0.01). By multivariate analysis, after adjusting for differences in SE, age, and SAP MD, there was no significant difference between the two groups (p=0.09). βPPA width in clock-hours significantly correlated with SAP severity and mfVEP latency, even after adjusting for age and SE. ßPPA eyes had lower amplitude log SNR (0.49±0.16 vs. 0.56±0.15, p<0.01), which lost significance (p=0.51) after adjusting for MD and PSD.
Although eyes with ßPPA had significantly lower amplitudes and prolonged latencies than eyes without ßPPA, these differences were attributable to differences in SAP severity, age, and refractive error. Thus, ßPPA does not appear to be an independent factor affecting mfVEP responses in eyes with GON.
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