Masking, Contrast Sensitivity, and Amblyopia
Citation Info
Nordmann, J.P., Freeman, R.D., and Casanova, C. (1992)
Contrast sensitivity in amblyopia: masking effects of noise.
Invest. Opthalmol. Vis. Sci. 33: 2975-2985.
Abstract
Contrast sensitivities were determined for sinusoidal gratings of
varying spatial frequencies with and without the presence of a random noise
pattern superimposed on the gratings. Control subjects with normal
binocular vision and observers with amblyopia were tested to determine the
relative effects of noise on contrast sensitivity. For both amblyopes and
normal subjects, contrast sensitivities are reduced by the presence of
noise. Effects are maximal at 4 cycles/degree and are minimal at low and
high spatial frequencies. Dichoptic presentation of noise and gratings to
opposite eyes is equivalent to monoptic results for both amblyopes and
normal subjects. Masking effects are eliminated if gratings are drifted
while noise patterns are static. The contrast sensitivity of amblyopes is
reduced by relatively similar amounts to that of normal subjects when noise
is added to the stimulus. Overall, masking effects are virtually identical
for amblyopes and for subjects with normal binocular vision.