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T. M. Kazam, E. C. Lai, C. E. Starr; Scotopic Pupil Size & Refractive Surgery: Should We Be Measuring the Dark Adapted Scotopic Pupil?. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2363.
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To compare dark-adapted to standard, non-dark-adapted scotopic pupil diameters utilizing the VISX CustomVue WaveScan system in the routine refractive surgery pre-op evaluation.
28 eyes of 15 healthy volunteers were examined using the VISX WaveScan Version 3.65. A set of three baseline (0 min) WaveScans were taken in a room with minimal ambient illumination. A standardized dark-adaptation protocol was then performed. Two additional sets of three scans were performed at 5 and 15 minutes of dark adaptation. The largest pupil diameter of the three scans at each interval of dark adaptation (0, 5, and 15 min) was included for each eye.
The mean subject age was 28.5 yrs. The average spherical equivalent refractive error of the subjects was -3.62 (-0.50 to -9.75). The average pupil diameter was 7.74 mm (-1.04 to +1.16) at baseline (0 min). At 5 min, pupil diameter was 7.45 mm (-1.45 to + 1.05); 15 min, 7.37 mm (-1.07 to +0.83). Using a t-test, the pupil diameters at 5 min were not found to be significantly different compared to baseline (p<0.10). At 15 min, pupil diameters were significantly smaller compared to baseline values (p<0.005).
Pupil size at 15 minutes of dark adaptation was unexpectedly found to be significantly smaller than that at baseline (0 min dark adaptation) utilizing the VISX WaveScan Version 3.65. This result suggests that ablation zone sizes in refractive surgery may be made smaller in comparison to those values obtained using current scotopic pupil measurement techniques. The smaller dark-adapted pupil size at 15 minutes may also have implications for increasing refractive surgery candidacy and reducing the incidence of night vision disturbances.
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