Purchase this article with an account.
G. Giraudet, C. Pédrono; Effect of Static Peripheral Cyclodisparities on Central Visual Perception . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3139.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Cyclovergence is a simultaneous torsional rotation about the visual axis of both eyes in opposite directions. Incyclovergence and excyclovergence mean that the eyes vertical meridians rotate respectively top in and top out. In the present study, incyclovergence was evoked by static cyclodisparities in the images perceived separately by the right and the left eyes. The aim was to determine the effect of cyclovergence induced by peripheral cyclodisparities on the perception of central stimuli displayed without disparity.
A natural scene with binocular cyclodisparities of 0, 3 and 6° was presented to 7 men, aged from 30 to 50 years. Subjects sat 1 meter from the stimulus and the scene subtended a viewing angle of 64.01° horizontally and 51.28° vertically. No visual information was provided in the 12° central circular field except a small fixation point in the centre. Landolt rings were briefly displayed (200 ms) around the fixation point. Subjects were instructed to localize the gap in the ring while keeping their fixation on the central point; four different responses could be possible: right, left, up and down. Contrast sensitivity threshold was determined by varying the Landolt ring contrast using a double adaptative staircase procedure. For a given cyclodisparity, the measurement of sensitivity threshold was repeated 3 times. Each subject performed 9 measurements in a controlled order.
Contrast sensitivity thresholds were analysed with a two way ANOVA with two within–subject factors: Level of disparity and Repetition. Results showed that there was a significant decrease of contrast sensitivity when cyclovergence was induced by binocular cyclodisparities (F[2;12]=3.90; p<0.05). Subjects’ sensitivity did not change when threshold measurement was repeated (F[2;12]=0.07; p>0.05). The interaction of both factors was not significant (F[4;24]=2.11; p>0.05).
The present results showed that small static cyclovergences from 3° evoked by peripheral cyclodisparities were sufficient to decrease contrast sensitivity for central stimuli displayed without disparity.
This PDF is available to Subscribers Only