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Physiological Loss of Retinal Central Function Assessed by Multifocal Electroretinogram

Dept of Ophthalmology, Federal University of Sao Paulo, Sao Paulo, Brazil

Commercial Relationships: A. Berezovsky, None; J.M. Pereira, None; P.Y. Sacai, None; S.E.S. Watanabe, None; S.R. Salomao, None.

Support: FAPESP grant#01/03364–6 to S.R. Salomao

Abstract

Purpose: Multifocal electroretinogram (mfERG) is a visual electrophysiological method for evaluation of localized regions of central retina. Its main clinical indications include retinal function evaluation in macular diseases, retinitis pigmentosa with central vision preservation, retinal toxicity (chloroquine, tamoxifen) among others. The purpose of this study is twofold: to investigate physiological loss of central retinal function in normal volunteers and to determine age norms for mfERG.

Methods: mfERGs were obtained from 4 different age groups: Group I – 24 subjects (16–24 years, mean 21.8± 1.9). Group II –16 subjects (25–34 years, mean 29.1± 3.0). Group III –11 subjects (35–44 years, mean 38.3± 2.5). Group IV – 13 subjects (45–55 years, mean 49.8± 3.8). The inclusion criteria were: best corrected visual acuity for distance = 0.0 logMAR (20/20), absence of visual complaints, negative family history for ocular disease, absence of previous ocular surgery and informed consent. The mfERG was obtained in one eye from a fully dilated pupil using a bipolar contact lens electrode. A total of 103 responses were obtained with white hexagonal stimulus (280 cd/m²) and black (0.45 cd/m²) enclosing 25° of retinal area, into six rings with eccentricities of 0°, 5°, 10°, 15°, 20° and 25°. Parameters of latency (ms) of the first negative deflection (N1) and of the first positive deflection (P1) and amplitude peak–to–peak (nV/degree²) N1–P1 had been calculated and statistically analyzed (one–way ANOVA) using data from the first order kernel.

Results:

Mean amplitude values and their respective standard deviations are shown in the following table for the six different eccentricities.

Mean peak–to–peak amplitudes (nV/degree²) N1–P1 for mfERGs were statistically reduced in the older group when compared to Groups I and II (P<0.05).Latency values were comparable for the 5 groups (P>0.05).

Conclusions: This study confirmed the physiological loss of retinal function with aging reflected by lower amplitudes and also provided normative data to help in the diagnosis of central retinal abnormalities.

Keywords: electroretinography: clinical • aging • retina

© 2005, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. For permission to reproduce any part of this abstract, contact the ARVO Office at arvo{at}arvo.org.