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M. Y. Kahook, D. L. Mackenzie, N. Faberowski, V. D. Durairaj, N. Mandava; Effect of Corneal Drying on Corneal Hysteresis Measurements Using the Ocular Response Analyzer. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1255. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the effect of corneal drying on corneal hysteresis measurements obtained by the Ocular Response Analyzer (ORA).
Cohort study of 10 subjects (mean age, 37 +/- 15 years) undergoing a series of corneal hysteresis measurements using the ORA in a randomly selected eye. Baseline data was acquired followed by taping the eyelid to prevent blinking. Two scan sets, each separated by 20 seconds, were then performed and recorded. A final scan set was obtained 2 minutes after removing the tape and allowing participants to blink freely. Data was analyzed using analysis of variance (ANOVA) and paired student’s t-test where appropriate. The main outcome measure was consistency of corneal hysteresis (CH) between time points.
Significant differences were noted in CH measurements (mm Hg) between baseline (7.12 +/-1.44), 40 seconds post taping the eyelid (9.48 +/-2.67), and 2 minutes after removing the tape (7.62 +/-1.33; p=0.03). The differences included both increases and decreases in CH measurements at the 40 second post-taping time point compared to all other time points. We also noted poor quality of recorded wave formation after taping the eye lids at both the 20 second and 40 second time points. There were no significant differences in CH measurements obtained at baseline, 20 seconds after taping (7.48 +/-1.56) and after removing the tape allowing for free blinking (p=0.73).
Corneal dryness may affect CH measurements by the ORA. Blinking frequently or instilling artificial tears prior to measuring CH with the ORA is recommended.
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