Share Email Print
cover

Proceedings Paper

Review on the use of Fresnel prism in low vision
Author(s): George C. Woo
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

Fresnel prisms are often prescribed for visual field defects in low vision patients. These prisms are made of optical polyvinyl chloride (PVC) and this material increases chromatic dispersion and produces a loss of contrast. In this presentation, the effect of chromatic dispersion on contrast sensitivity is determined. It has been verified that loss of contrast sensitivity is greater at higher spatial frequencies with Fresnel prisms than with glass prisms of the same power. Above 10 prism diopters, Fresnel prisms reduce both contrast sensitivity and visual acuity substantially. However, low vision patients with visual field losses appear not to be affected due to their sometimes very low remaining contrast sensitivity and visual acuity. In the presence of both blurred and diplopic vision, a case report indicating the use of prisms in alleviating diplopia caused by trauma is presented. In spite of a reduction in visual acuity and contrast sensitivity, the patient preferred to have the Fresnel prism on his spectacle lenses for distance viewing. Diplopia appeared to cause more annoyance than the reduction of acuity and contrast sensitivity due to the Fresnel prism.

Paper Details

Date Published: 14 August 1992
PDF: 6 pages
Proc. SPIE 1644, Ophthalmic Technologies II, (14 August 1992); doi: 10.1117/12.137428
Show Author Affiliations
George C. Woo, Univ. of Waterloo School of Optometry (Canada)


Published in SPIE Proceedings Vol. 1644:
Ophthalmic Technologies II
Jean-Marie Parel, Editor(s)

© SPIE. Terms of Use
Back to Top