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Osamu Katsumi, Yoshitaka Miyanaga, Takako Tachikawa, Kenji Inouye; Contrast Visual Acuities In Patients With Orthokeratology. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6549.
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© ARVO (1962-2015); The Authors (2016-present)
To measure contrast visual acuities (VAs) in patients treated with orthokeratology.
Twenty-two eyes of 11 patients (4 men, 7 women; age, 28~40; mean±SD, 33.9±4.74) who visited the Nishikasai Inouye Eye Clinic, Tokyo, from January to November 2010 were included. Their uncorrected VAs before orthokeratology ranged from 0.04 to 0.3 (mean±SD, 1.0/0.29 logMAR) and their refractive errors (expressed as the spherical equivalent) ranged from -1.70 to -7.63 diopters (D) (mean±SD, -4.13±1.62). We measured the contrast VA of these eyes using the Multiple Contrast Acuity Chart, which is comprised of four contrast charts of 90%, 90% contrast with reverse polarity, 15% contrast, and 5% contrast. Each chart was comprised of 13 pairs of optotypes geometrically arranged. The contrast VA profile was analyzed by comparing the scores between different contrast charts and with the number of correctly answered optotypes (as expressed with points, 0~26 points). 26 points indicate level 13, which is VA of 20/10, logMAR=-0.301. Similarly, 20 points, VA of 20/20, logMAR=0 and 14 points, VA of 20/40, logMAR=0.301. The mean VA and refractive error at the time of the contrast VA examination were -0.15/0.11 logMAR and -0.45/0.39 D, respectively. The duration of treatment with orthokeratology at the time of contrast VA measurement was 6 to 11 months (mean±SD, 8.18/1.94 months).
Regarding contrast VA, the patients undergoing orthokeratology scored 21.27 (SD, 1.32) points with the 90% chart and 21.86±1.40 points with the 90% reverse polarity chart (+2.77% vs. 90%, ANOVA Dunnett test, NS). The contrast VA at 15% contrast was 18.14±1.67 points (-14.72% vs. 90%, P<0.01) and 12.82±2.72 points with 5% contrast (-39.83% vs. 90%, P<0.01) and the total contrast VA was 73.82±6.36 points. Although the contrast VAs were within the normal range with 15% and 5% contrast, the slightly increased VA score with the 90% reverse polarity chart suggested a possible corneal aberration.
Based on the results of contrast VA measurement in patients treated with orthokeratology, the presence of a corneal aberration was suspected.
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