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Peripheral resolution using stationary and flickering gratings: the effects of age
1Vision Science Research Group, School of Biomedical Sciences, University of Ulster at Coleraine, Co., Londonderry, Northern Ireland. rs.anderson@ulst.ac.u
Purpose:
Currently, little or no psychophysical data exist on the decline in retinal ganglion cell density, with age or on the nature of any selective age-related loss of one cell type over another. The authors wished to determine the nature of any decline in ganglion cell density with age using measurements of peripheral grating resolution, which is directly related to ganglion cell sampling density.
Methods:
We measured grating resolution at 4 different retinal locations in a group of 97 normal subjects ranging in age from eight to eighty-one years. Stimuli were either stationary or employed counterphase flicker at 30 Hz in order to selectively stimulate a greater proportion of either P or M ganglion cells.
Results:
Mean resolution was significantly higher for stationary gratings than flickering gratings. Loss of peripheral resolution was approximately 5%/decade for stationary gratings and 6%/decade for flickering gratings. The ratio of resolution for flickering/non-flickering stimuli showed a small but insignificant decline with age.
Conclusions:
There is a general decline in peripheral resolution with age, indicating a corresponding loss of retinal ganglion-cell density. This age-related loss does not appear to be very selective in terms of cells that are sensitive to either stationary or flickering gratings. These results increase the diagnostic power of clinical tests that employ measures of peripheral resolution in subjects of different ages to detect diseases which cause loss of ganglion cells.