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B.J. Brooks, W. Sams, B. Ambati; Seasonal variations in pupil size: a factor in determining refractive surgery treatment zones . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2826.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine if seasonal variations exist in pupil size. Methods: Thirty–six eyes of 18 subjects ages 25–57 years (average age 38.1 years) were involved in the study. Using a OASIS Colvard pupillometer, scotopic pupil measurements were taken in both eyes by one examiner in June and then again in late November. Results:Twenty of the 36 eyes (56%) had larger pupils in November as compared to June. The average increase was 0.48mm (range 0.1–1.2mm, SD +/–0.31mm). Thirteen of the 36 eyes (36%) had smaller pupils in November with an average decrease of 0.42mm (range 0.1–0.5mm, SD +/– 0.36mm). Three eyes had no change in pupil size when measured in summer (June) and fall (November). Conclusions: Greater than 50% of eyes in this study had larger scotopic pupil measurements in the fall than in the summer. This is of particular concern for refractive surgeons and patients when determining appropriate treatment zones. A scotopic pupil measurement performed in summer months may therefore be inaccurate in fall and winter when the eye may exhibit a relative mydriasis due to fewer daylight hours. This disparity in the seasonal variability of scotopic pupil measurements and treatment zones may contribute to glare disability and haloes in the postoperative refractive patient. Larger surveys of scotopic pupil measurements and incidence of glare and haloes would be useful to validate these findings for clinical application.
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