Impact of high power and angle of incidence on prism corrections for visual field loss

Jae-Hyun Jung; Eliezer Peli

doi:10.1117/1.OE.53.6.061707

17 January 2014 Impact of high power and angle of incidence on prism corrections for visual field loss

Jae-Hyun Jung, Eliezer Peli

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Optical Engineering, Vol. 53, Issue 6, 061707 (January 2014). https://doi.org/10.1117/1.OE.53.6.061707

Abstract

Prism distortions and spurious reflections are not usually considered when prescribing prisms to compensate for visual field loss due to homonymous hemianopia. Distortions and reflections in the high-power Fresnel prisms used in peripheral prism placement can be considerable, and the simplifying assumption that prism deflection power is independent of angle of incidence into the prisms results in substantial errors. We analyze the effects of high prism power and incidence angle on the field expansion, size of the apical scotomas, and image compression/expansion. We analyze and illustrate the effects of reflections within the Fresnel prisms, primarily due to reflections at the bases, and secondarily due to surface reflections. The strength and location of these effects differs materially depending on whether the serrated prismatic surface is placed toward or away from the eye, and this affects the contribution of the reflections to visual confusion, diplopia, false alarms, and loss of contrast. We conclude with suggestions for controlling and mitigating these effects in clinical practice.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Jae-Hyun Jung and Eliezer Peli "Impact of high power and angle of incidence on prism corrections for visual field loss," Optical Engineering 53(6), 061707 (17 January 2014). https://doi.org/10.1117/1.OE.53.6.061707

Published: 17 January 2014

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