Intermittent exotropia: stimulus characteristics affect tests for retinal correspondence and suppression.
OBJECTIVE
Prior studies have reported various sensory responses in subjects with intermittent exotropia [X(T)]. These varying responses have been proposed due to differences in stimulus targets, backgrounds, or even a lack of control of binocular alignment. This study investigated the effects of varying target and background stimuli while controlling binocular alignment.


METHODS
Eight X(T)s of the divergence excess or basic type were presented dichoptic computer generated visual stimuli while an infra red eye movement monitoring system determined horizontal eye position of each eye. Target and background were varied to assess their effect on sensory responses during latent and manifest exotropia.


RESULTS
Most of our X(T)s demonstrated, while tropic, a consistent, i.e., dominant, type of retinal correspondence, i.e. a response that occurred on most tests, independent of the stimulus or background used for testing. Four subjects demonstrated harmonious anomalous retinal correspondence (HARC) while three subjects demonstrated normal retinal correspondence (NRC) with three out of four of the tests. In two out of four stimuli used for testing, one subject demonstrated NRC and another HARC.


CONCLUSIONS
Complex backgrounds resulted in the largest number of suppressions, whereas blank backgrounds decreased the number of reported suppressions.
Cooper
J
J
State College of Optometry, State University of New York, Schnurmacher Institute for Vision Research, New York, New York 10010, USA.
Feldman
J
J
Pasner
K
K
D000221:Adaptation, Ocular / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D002648:Child; D003867:Depth Perception / Q000502:physiology; D005099:Exotropia / Q000503:physiopathology*; D005133:Eye Movements / Q000502:physiology; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000503:physiopathology; D010775:Photic Stimulation; D012160:Retina / Q000503:physiopathology*; D015357:Vision Disparity / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology*