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EFFECT OF FRESNEL PRISM DISPERSION ON CONTRAST SENSITIVITY FUNCTION *
Author(s) -
Woo George C.,
Campbell Fergus W.,
Ing Brian
Publication year - 1986
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.1986.tb01162.x
Subject(s) - optics , contrast (vision) , prism , sensitivity (control systems) , dispersion (optics) , physics , engineering , electronic engineering
— Fresnel prisms are often used in orthoptics for binocular anomalies and in low vision for visual field defects. These prisms are made of optical polyvinyl chloride (PVC) and this material increases chromatic dispersion and produces a loss of contrast. In this study, the effect of chromatic dispersion on contrast sensitivity is determined. Contrast thresholds over a wide range of spatial frequencies are obtained on a number of subjects with the use of Fresnel prisms ranging from 5 to 30 prism dioptres. As predicted there is a decrease in visual acuity and cut‐off spatial frequency threshold as prism power increases. Similarly, a decrease in contrast sensitivity at high and medium spatial frequencies is recorded.