Abstract

Along with reduced acuity, amblyopia is usually associated with a stereo-acuity deficit. Indeed, stereo testing has been recommended as an effective means of screening for amblyopia (Kani, 1978, Reinecke and Simons, 1974). The absence of stereo depth perception however does not preclude other forms of binocular interaction. Anderson, Mitchell and Timney (1980) have demonstrated interocular transfer of contrast threshold elevation in amblyopes. The contrast elevation is normal for spatial frequencies where contrast sensitivity was equal in the two eyes and was virtually absent at other frequencies (Selby and Woodhouse, 1981). Levi et. al. (1979) report interocular threshold elevations which are tuned for size and orientation in stereoblind amblyopic observers. Another example of binocular integration has been reported using flickering stimuli which lack spatial structure (Baitch and Srebro, 1990; Baitch and Levi, 1989). With different frequencies in each eye, temporal beat frequencies are perceived in observers with binocular function. However, these measures have limited utility in a clinical setting where the time for training and testing is restricted. Our goal in this project is to evaluate a cyclopean motion test of binocular integration for use in a clinical setting and assess its sensitivity to residual binocular function in amblyopes. Binocular integration is required for the perception of continuous motion with this cyclopean motion stimulus, neither eye's image alone contains a direction cue (Carney, et al, 1987; Shadlen and Carney, 1986). Horizontal disparity does not provide a cue either, therefore the subject does not necessarily need stereopsis to perceive the motion. The stimuli can be briefly presented and the task is simply to indicate perceived direction of motion, up or down. Moreover, the stimuli can be used to evaluate binocular integration at specific spatial frequencies and have the advantage that moderate horizontal misalignment of the eyes can be tolerated. The cyclopean motion stimulus might provide information concerning binocular integration for stimuli with spatial structure beyond that obtained with standard clinical tests of stereo-acuity.

© 1992 Optical Society of America