{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,5]],"date-time":"2026-09-05T18:02:43Z","timestamp":1788631363673,"version":"build-2803163510"},"reference-count":30,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2007,5,1]],"date-time":"2007-05-01T00:00:00Z","timestamp":1177977600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2007,5,1]],"date-time":"2007-05-01T00:00:00Z","timestamp":1177977600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["OVS"],"published-print":{"date-parts":[[2007,5]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Purpose.<\/jats:title>\n                    <jats:p>To evaluate the refractive error and visual acuity (VA) at various contrast levels in the two eyes of overnight orthokeratology (ortho\u2010k) subjects, and to compare their postortho\u2010k VA with the best corrected VA of spectacle\u2010wearing control subjects matched for age, gender, and initial refractive error.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods.<\/jats:title>\n                    <jats:p>Distance postortho\u2010k uncorrected and best corrected logMAR VA at four different contrast levels of 31 ortho\u2010k (test) subjects (aged 7\u201335 years old) and the best corrected VA of 31 spectacle\u2010wearing (control) subjects were measured and compared using the Waterloo Four\u2010Contrast LogMAR VA Chart, which incorporated four sets of letters at different contrast levels: 90%, 48%, 21%, and 7%. Noncycloplegic manifest refractive error was measured in both eyes.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results.<\/jats:title>\n                    <jats:p>The mean \u00b1 SD percentage reductions in spherical equivalent achieved in the current study were 92% \u00b1 11% in the better eye and 84% \u00b1 14% in the worse eye of the test subjects. Postortho\u2010k uncorrected VAs were significantly correlated with the residual overall blurring strength (length of the vector representing the residual refractive error) in both eyes at all contrast levels. The mean postortho\u2010k uncorrected VA in the better eye were 0.00 \u00b1 0.11, 0.08 \u00b1 0.11, 0.21 \u00b1 0.12, and 0.46 \u00b1 0.13 with the 90%, 48%, 21%, and 7% contrast charts, respectively. These were comparable to the best corrected VA of the better eye of the control group with the 90% (\u20130.03 \u00b1 0.07) and 48% contrast charts (0.03 \u00b1 0.09), but worse than those of the control group with the 21% (0.13 \u00b1 0.10) and 7% (0.35 \u00b1 0.13) contrast charts. Postortho\u2010k VA, with the four different contrast charts, improved by 0.07 to 0.12 log units in the better eye and 0.15 to 0.18 log units in the worse eye after correction of the residual refractive error; the improved VA was comparable to the best corrected VA of the control group.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions.<\/jats:title>\n                    <jats:p>Postortho\u2010k visual outcomes were compromised primarily due to the presence of residual refractive error. Although the uncorrected postortho\u2010k VA was comparable to the best corrected VA of the spectacle wearers at high\u2010contrast levels, it was worse at low\u2010contrast levels and caused a significant between\u2010eye difference at all contrast levels. Therefore, we suggested that monocular VA at high\u2010 and low\u2010contrast levels should be evaluated for ortho\u2010k patients.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1097\/opx.0b013e31804f5acc","type":"journal-article","created":{"date-parts":[[2007,5,9]],"date-time":"2007-05-09T04:03:12Z","timestamp":1178683392000},"page":"410-416","source":"Crossref","is-referenced-by-count":30,"title":["Refractive Error and Visual Acuity Changes in Orthokeratology Patients"],"prefix":"10.1002","volume":"84","author":[{"given":"Sin Wan","family":"Cheung","sequence":"first","affiliation":[{"name":"School of Optometry, The Hong Kong Polytechnic University Kowloon Hong Kong SAR China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pauline","family":"Cho","sequence":"additional","affiliation":[{"name":"School of Optometry, The Hong Kong Polytechnic University Kowloon Hong Kong SAR China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wan 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