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dc.contributor.authorCarim-Sanni, Ridwan
dc.description.abstractThe Photopic Negative Response is a component of the light-adapted electroretinogram (ERG) that is reduced in glaucomatous eyes and the Bruch’s Membrane Opening - Minimum Rim Width (MRW) than Retinal Nerve Fiber Layer (RNFL) thickness are two structural measures of retinal ganglion cell related structures that are disrupted in glaucomatous eyes. The purpose of our investigation was to determine whether the PhNR amplitude in primary open angle glaucoma patients is better correlated with Bruch’s Membrane Opening - Minimum Rim Width (MRW) than Retinal Nerve Fiber Layer (RNFL) thickness. Methods: Full-field Photopic Flash ERGs to brief red flashes delivered on a rod-saturating blue background were recorded from one eye of glaucoma patients (N=10) and age-matched controls (N=10) using an electrophysiological system from Diagnosys (Lowell, MA). The PhNR and b-wave responses of the ERG was plotted as a function of test flash strength and fitted with a generalized Naka-Rushton equation to derive values for saturated amplitude, slope and semi-saturation constant. BMO-MRW and peripapillary RNFL thickness were measured from the same eyes using a Spectral-Domain Optical Coherence Tomography system (Spectralis SD-OCT, Heidelberg Inc, Germany). Visual field sensitivity was assessed with the Humphrey Visual Field Analyzer 24-2 SITA standard test (Carl Zeiss Meditec, USA). ERG Naka-Rushton fit parameters were compared between glaucoma patients and age-matched controls. Linear regression analysis was used to study the correlation of significant fit parameters with BMO-MRW, RFNL and average visual field sensitivity. Results: Of the three different Naka-Rushton fit parameters derived for the PhNR and b-wave only the saturated amplitude of the PhNR was significantly different between glaucomatous and control subjects (p=0.000002). The PhNR saturated amplitude was significantly correlated only with with BMO-MRW in control eyes (r=0.74, m=0.1, p=0.0002) and in glaucomatous eyes showed a better correlation with BMO-MRW (r=0.91, m=0.05, p=0.0002) than with RNFL thickness (r=0.7, m=0.18, p=0.03). PhNR saturated amplitude was also correlated with average behavioral visual sensitivity in glaucomatous eyes (r=0.72, m=29.9, p=0.02). Conclusion: The variance in PhNR amplitude in control and glaucomatous eyes is better accounted for by BMO-MRW than RNFL thickness. This finding may reflect an optic nerve head and prelaminar optic nerve being the locus of PhNR generation as well as early pathogenic events in glaucoma.en_US
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 International*
dc.subjectERG, Photopic negative response (PhNR)en_US
dc.subjectBuchs membrane Opening minimum rim width (BMO-MRW)en_US
dc.titleStructure function correlation of ERG photopic negative response (PhNR) and OCT Buchs Membrane Minimum Rim Width (BMO-MRW) in Primary Open Angle Glaucoma (POAG)en_US
dc.typeMasters Thesisen_US
dc.description.institutionSUNY College of Optometryen_US

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Attribution-NonCommercial-NoDerivatives 4.0 International
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