Local measures of psychophysical sensitivity, visual acuity and electroretinographic function in patients with age-related macular degeneration
 
J. Szlyk, Ph.D.1,2, W. Seiple, Ph.D.1,3, J. Paliga, BS2, T.S. Vajaranant, MD2, N.P. Blair, MD2, J.S. Pulido. MS, MD2
 
1Research and Development Service, Chicago Veterans Administration Health Care System, West Side Division, 2University of Illinois at Chicago, 3New York University School of Medicine
 
Objectives: Our laboratory has developed a system to measure visual acuity at 27 discrete locations. Our rationale for the development of the instrument was to identify areas of remaining vision to be utilized for eccentric "surrogate" fixation areas for patients with central retinal diseases. As a validation of this new technology, the objective of this study was to examine the relationships among psychophysical and electroretinographic (multifocal ERG) measures of central visual function.
 
Methods: Twelve patients with non-exudative age-related macular degeneration were recruited. The patients ranged in age from 54 to 82 years (Median = 77.5 yrs.) and visual acuities ranging from 20/20 to 20/200. MfERG responses were recorded using 103 scaled hexagons. Humphrey visual field thresholds were measured at locations corresponding to the mfERG hexagons within the central 10° of the visual field. Local visual acuity was measured using an instrument that we recently developed that allows stimulus presentation under direct fundus viewing. This ensured accurate placement of targets on the retina. Acuity was measured in 27 locations within the central 10°.
 
(Szlyk) A representative case of AMD patient with geographic atrophy in the macula.
 
Results. The patients' mean visual acuities were significantly worse than normal at all 27 locations tested. Visual field thresholds were also elevated at 42 of 45 locations. Local analyses of the mfERG show reduced amplitudes and delayed implicit times, predominantly within the central 10°.
 
Conclusions: There was a good correspondence among the three measures of central retinal function.
 
Funding Acknowledgment: This study was funded by the Department of Veterans Affairs, Rehabilitation Research and Development Service, project # C2478R.