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K. W. van Gaalen, S. A. Koopmans, N. M. Jansonius, T. Terwee, A. C. Kooijman; A Comparison of Widely Used Clinical Contrast Sensitivity Tests: Measurements in Phakic Healthy Subjects With a Natural Pupil Size. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2784.
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© ARVO (1962-2015); The Authors (2016-present)
We compared a variety of contrast sensitivity (CS) tests and related the measured CS values to spherical aberration (SA) in healthy phakic subjects. The purpose is to find a CS test that can be used clinically to evaluate interventions that aim to minimize higher order aberrations.
48 healthy subjects, age 20-35 years and 55-70 years, participated. SA was measured with a wavefront analyzer (WASCA version 1.26.3, Asclepion Meditec, Jena, Germany). CS was measured with two computerized tests, one with vertical sine-wave gratings (1.5-12 cpd) generated on a CRT (Cambridge Research Systems, Rochester, UK; Von Bekesy tracking method) and the Holladay sine-wave (6 cpd) modulated circular lines (HACSS) (M&S Technologies, Skokie, Illinois, USA). Five CS chart tests were used: the Pelli Robson (PR) CS test, two low contrast ETDRS-like optotype charts (2,5% and 10%), and two edge CS tests (GECKO and GECKO-100). CS tests where performed in mesopic (3 cd/m2) and photopic (160 cd/m2) conditions, using the dominant eye. Tests were performed without cycloplegia and the pupil size was measured in both luminance conditions.
CS was lower in the mesopic condition than in the photopic condition. Mean CS in elderly subjects was lower than in the younger subjects. In both edge CS tests, subjects could see the most difficult targets of the chart. In mesopic conditions, some subjects could not read the largest optotypes of the 2,5% ETDRS-like optotype chart. Mean SA in elderly eyes was larger than in younger eyes. Results obtained with the PR and the HACSS showed some decrease of CS with increasing SA in the elderly group in mesopic conditions.
The two edge contrast sensitivity tests and the 2,5% contrast ETDRS-like optotype chart are inappropriate to assess small differences in CS, due to ceiling and floor effects. With the 10% contrast ETDRS-like optotype chart we found no correlation between CS and SA, which might be due to the size of the optotypes in this test. In the elderly group, we found a non-significant decrease of CS with increasing SA in the measurements with the PR and the HACSS in mesopic conditions. A possible explanation for the lack of statistical significance is that our measurements were performed without mydriasis, in contrast to most clinical studies on SA. Despite carefully controlled luminance levels, pupil size appeared to vary considerably both within and between subjects.
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