Abstract
Purpose: :
To determine the effects of age and retinal pathology on thresholds for speed discrimination in three groups of subjects, young normals, older normals, and patients with central visual field loss due to age-related macular degeneration (AMD).
Methods: :
Five groups of observers made speed discrimination judgments. The groups were younger normals aged 21-50 years, older normals aged =>60 years and low vision patients with AMD aged =>60 years, low vision patients with diabetic retinopathy aged > 60 and AMD patients treated with anti-VEGF who maintained good binocular visual acuity aged >60 years . Observers were seated 50 cm from a display that subtended 44.6 arc deg in the horizontal dimension. Pressing a mouse began a trial. During the 833 mS trial, a pattern of 100 white dots on a black background appeared. The observer saw four regions on the screen. Alternating regions of the screen moved in opposite directions, 25 dots in each region, at random locations and moved either left to right or right to left. Dots had a lifetime of 467 mS or were replaced as they moved off of the screen. The observers’ task was to determine which of the two directions of motion had faster moving dots.
Results: :
Younger normals (p<0.01) discriminated speed differences better than all of the other groups. None of the other groups differed in their ability to discriminate speed (p>0.10). Age as a variable had a higher correlation with relative speed discrimination than either binocular visual acuity or contrast sensitivity (r=0.5036, r = 0.3045, r = -0.358, respectively). Age was the only variable which significantly predicted speed discrimination in a multiple regression analysis (p < 0.05).
Conclusions: :
The results are consistent with data indicating an age-related decline in motion perception. Given that relative speed discrimination is correlated with mobility performance, the data are also consistent with age-related changes in mobility.
Keywords: aging: visual performance • low vision • age-related macular degeneration