Original articlePrediction of letter contrast sensitivity using videokeratographic indices☆
Section snippets
Patients and methods
We studied 59 eyes of 51 patients (men, 29; women, 22). The eyes were divided into two groups: one group, with 20 eyes of 20 cases, had normal corneas and served as the controls (mean age, 28.3 ± 4.6 years). The second group, with 39 eyes of 31 cases, had abnormal corneal topography resulting from keratoconus (mean age, 27.4 ± 8.6 years). All the eyes had a best spectacle-corrected visual acuity 20/20 or better, and there were no abnormal ocular findings except for the refractive error and
Results
A comparison of letter contrast sensitivity in the normal control group and the abnormal topography group is shown in Figure 1. The abnormal topography group had a significantly greater loss of letter contrast sensitivity (number of correctly identified letters = 19.1 ± 2.5 letters, median 20.0 letters) than the normal control (number of correct letters = 22.6 ± 1.2 letters, median 23.0 letters, P = .0001, Mann-Whitney Rank Sum test). This was found despite the fact that all the subjects in
Discussion
Since Campbell and Gubisch24 first suggested that measurement of contrast sensitivity can provide a more comprehensive measure of spatial vision than the measurement of visual acuity, contrast sensitivity testing has become popular in clinical practice.25, 26 However, it has been argued that contrast sensitivity testing is mainly supplementary to Snellen acuity determination, and there is no benefit in the measurement of contrast sensitivity for clinical management, except where acuity is found
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2016, Journal of Cataract and Refractive SurgeryCitation Excerpt :Contrast sensitivity is an index that assesses visual function more sensitively than visual acuity.45 Some studies report patients with good visual acuity but poor contrast sensitivity as a result of conditions such as keratoconus,46 after laser in situ keratomileusis,47 cataract,48 and retinal diseases.49 The reduction in contrast sensitivity is often associated with increases in ocular HOAs,50–52 representing the deterioration of the optical quality of the eye.
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This work was supported in part by grant-in-aid No. 11671737 for scientific research from the Japanese Ministry of Education, Science, Sports, and Culture (Dr Maeda), and by a research grant from the Osaka Eye Bank, Suita, Japan (Dr Maeda).