Letter contrast sensitivity function of the eye.
OBJECTIVE
To provide empirical data of letter CSF for various levels of defocus under controlled conditions of luminance and age.


METHODS
Corrected distance visual acuities were tested at different levels of contrast and defocus. An experiment was conducted using the Medmont visual acuity tester on 10 young subjects and under normal room lighting.


RESULTS
Empirical data of visual acuity were obtained for 7 levels of contrast (5, 10, 15, 25, 40, 60, 80%) and defocus levels of 0, +1 and +2D. A mathematical model was derived (R2=0.995) and this can be used to estimate visual acuity at various contrast levels for defocus of < or =+2D.


CONCLUSIONS
This information is useful for the clinician as normative data and for further development of optical models to predict visual performance of the eye.
Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, Australia.
H L
HL
Liou
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NA
Brennan
D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D008027:Light; D008962:Models, Theoretical; D009799:Ocular Physiological Phenomena; D012016:Reference Values; D014787:Vision Tests / Q000295:instrumentation*; D014792:Visual Acuity / Q000502:physiology