Additional usage possibilities for the computerized Hess screen

Aiga Svede; Janis Dzenis

doi:10.1117/12.517042

8 August 2003 Additional usage possibilities for the computerized Hess screen

Aiga Svede, Janis Dzenis

Proceedings Volume 5123, Advanced Optical Devices, Technologies, and Medical Applications; (2003) https://doi.org/10.1117/12.517042
Event: 2003 Chapter books, 2003, Bellingham, WA, United States

Abstract

The purpose of the study was to work out a method how to use the computerized Hess screen in proximal vergence measurements. Proximal vergence or vergence due to knowledge of nearness is one of four independent components making up the total vergence response. Proximal vergence is expressed as a ratio - proximal convergence/test distance (PC/T). The computerized Hess screen is usually used to detect and to measure an ocular misalignment in patients with paralytic strabismus in different directions of gaze. The computerized Hess screen can be used to assess PC/T ratio in different directions of gaze, providing the open-loop disparity vergence and accommodation systems and assuming that tonic vergence is stable. The fusional system loop is opned using red/green filter goggles, objects with different size and color, a completely darkened room, and vertical dissociation (using a prism). The accommodation system loop is opened using pinhole. The test was performed on 16 neurologically and binocularly normal subjects (14 women, 2 men; average 24 y., 20-38 y.) Average PC/T ratio in a primary position for the whole group was 2.8pd/D with a standard deviation ±0.8 pd/D, which correlates with results in literature obtained by other methods.

Citation Download Citation

Aiga Svede and Janis Dzenis "Additional usage possibilities for the computerized Hess screen", Proc. SPIE 5123, Advanced Optical Devices, Technologies, and Medical Applications, (8 August 2003); https://doi.org/10.1117/12.517042

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KEYWORDS

Eye

Prisms

Goggles

Laser safety equipment

Projection systems

Computing systems

Distance measurement

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