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The relative sensitivity of visual acuity and small letter contrast sensitivity in early cataract
Author(s) -
Elliot David B.,
Situ Ping
Publication year - 1996
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 - 10.1046/j.1475-1313.1996.96833503.x
Subject(s) - visual acuity , contrast (vision) , ophthalmology , medicine , optometry , spatial frequency , test (biology) , audiology , optics , physics , biology , paleontology
Purpose: To investigate the effects of early cataract on spatial frequency dependent contrast sensitivity (CS) measurement and log MAR visual acuity (VA) assessment. Methods: The relative sensitivity of two computer‐generated letter CS tests, 1/9.5 letter CS (1/9.5 LCS) (assessing low to medium spatial frequency CS) and 6/9.5 letter CS (6/9.5 LCS) (measuring high spatial frequencies), and a log MAR VA test were evaluated in 19 subjects with early cataract and 21 age‐matched controls. Results: Results indicate that these three tests decline with increasing cataract formation. The greatest visual reduction and the highest test discriminative ability were found with the 6/9.5 LCS test (Az score of 0.441 versus 0.408 for VA) and the lowest with the 1/9.5 LCS test (Az score of 0.383). However, measurement variability was greatest for 6/9.5 LCS. After correcting for this variability, the 6/9.5 LCS test still proved slightly more sensitive to early cataract and cataractous change than the other two measurements. Conclusion: The study suggests that 6/9.5 LCS or other size small letter CS tests are able to detect more subtle vision loss in cataract than visual acuity.