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. 2000 Jul;7(2):18-26.

The effect of induced visual stress on three dimensional perception

F Abd-Manan  1
Affiliations

The effect of induced visual stress on three dimensional perception

F Abd-Manan. Malays J Med Sci. 2000 Jul.

Abstract

Previous studies have shown that stress on the vergence and accommodation systems, either artificially induced or naturally occurring, results in small misalignment of the visual axes, reduces binocular visual acuity and produces symptoms of ocular discomfort. This study examines the effect of artificially induced visual stress using ophthalmic prisms on three dimensional perception on 30 optometry students ages ranging from 19 to 29 years old. 6D base-in prisms, equally divided between the eyes (3D base-in each) was used to induce stress on the visual system producing misalignment of visual axes known as fixation disparity. The fixation disparity is quantified using near vision Mallett Unit and an enlarged scaled diagram. Stereoscopic perception was measured with the TNO test, with and without the presence of stress and the results was compared. Wilcoxon's matched pair ranked tests show statistically significant difference in the stereo thresholds of both conditions, p = 0.01 for advancing stereopsis and p = 0.01 for receding stereopsis, respectively. The study concludes that visual stress induced by prisms, produce misalignment of the visual axes and thus reduces three dimensional performance.

Keywords: prism induced; stereoacuity; stereopsis; visual stress.

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Figures

Figure 1:
Figure 1:
A TNO test booklet with red and green glasses
Figure 2:
Figure 2:
The graphic diagram of the hidden test object for the test Plates V to VII presented right side up. The numbers showed on each plates represent the levels of image disparities second of arc.
Figure 3.
Figure 3.
The graphic diagram of the hidden test object for the test Plates V to VII presented right side up. The numbers showed on each plates represent the levels of image disparities second of arc.
Figure 4.
Figure 4.
The Mallet Unit for near vision with a frame to hold a TNO test plate
Figure 5.
Figure 5.
A specially constructed bifiltered spectacled with red and green glasses on the top halves and crossed polaroid filters on the lower halves
Figure 6:
Figure 6:
An enlarged scaled diagram
See this image and copyright information in PMC

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