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Emily Freeman, Nabin Joshi, Mitchell W Dul, Suresh Viswanathan; Macular changes in multifocal photopic negative response (mfPhNR) and visual field sensitivity in glaucoma patients. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5850.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the relationship between mfPhNR amplitude and visual field sensitivity (VFS) changes in the macula of open angle glaucoma patients.
Multifocal electroretinograms were recorded with an Espion system (Diagnosys LLC) from 16 open angle glaucoma patients and 13 age-matched controls. The stimulus consisted of a 10 degree circular patch divided into 4 quadrants. The 13 ms white stimulus (1000 cd/m2), followed by at least 267 ms of blank frames, was presented on a white background (30 cd/m2). Superior and inferior hemifield (SF & IF) responses were obtained by adding the responses of the quadrants in the respective hemifields. The mfPhNR amplitude was measured at a fixed time from baseline and normalized to the b-wave (NmfPhNR) to minimize variability. Behavioral VFS was measured using the 10-2 SITA Standard strategy of the Humphrey Visual Field Analyzer (Carl Zeiss Meditec, Inc.). The correlation of mean deviation (MD) of VFS loss in dB to the NmfPhNR amplitude was evaluated with a simple linear model (SLM) previously used to describe the relationship between multifocal visually evoked potential amplitude and VFS loss [Hood et al., IOVS 2002]. The SLM in the current context assumes that the NmfPhNR amplitude reduces linearly with VFS loss to a point where it reaches a plateau as VFS deteriorates further.
The MD (dB) in glaucomatous eyes ranged from -33.71 to +0.68 in the SF and -20.82 to +0.44 in the IF and were significantly different from controls for both hemifields (SF: p=0.012; IF: p=0.0017). However, the NmfPhNR amplitude of the glaucomatous eyes was significantly different from control eyes only in the SF (p=0.03). The average NmfPhNR for the control eyes were 43% and 41%, respectively, for SF and IF. Based on the mean NmfPhNR values of the control eyes and MD values of the glaucomatous eyes the model predicted that the NmfPhNR amplitudes will reduce linearly with visual field sensitivity loss to reach a plateau at 4% and 7% NmfPhNR amplitudes in the SF and IF. The SLM provided a reasonable fit to the data with summed NmfPhNR amplitude residuals for SF and IF close to zero.
The NmfPhNR and VFS were reduced in the macula of glaucoma patients. The SLM provides a reasonable description of the data that relates NmfPhNR amplitude in the macular region to corresponding VFS losses in glaucoma.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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