1/19/2023 0 Comments Average pupil sizeHowever, it is not known to what extent genes and environment are important in determining the size of pupils in the population. Some conditions are known to reduce the size of dilated pupils, such as diabetes mellitus and pseudoexfoliation. Large pupils make cataract surgery easier and quicker 1 and allow for more thorough examination of peripheral retina, which may be important in the success of retinal detachment surgery. In clinical practice there is a wide variation in pupil size after mydriasis. Age only accounted for 2–3% of the variance and refractive error and iris colour did not significantly contribute to the variance.ĬONCLUSIONS Pupil size after mydriasis is largely genetically determined, with a heritability of up to 80%. Individual environmental factors explained 18–19% of the variance in this population. A model specifying additive genetic and unique environmental factors showed the best fit to the data, yielding a heritability of 78–80%. RESULTS Dilated pupil size was more highly correlated in MZ compared with DZ twins (intraclass correlation coefficients 0.82 and 0.39 respectively). Univariate maximum likelihood model fitting was used to estimate genetic and environmental variance components. Dilated pupil size was measured using a standardised grid superimposed over digital retroillumination images taken 50–70 minutes after mydriasis using tropicamide 1% and phenylephrine 10%. METHODS 506 twin pairs, 226 monozygotic (MZ) and 280 dizygotic (DZ), aged 49–79 (mean age 62.2 years, SD 5.7) were examined. A classic twin study was established to examine the relative importance of genes and environment in the variance of pupil size after mydriasis, and to examine the effects of other factors such as age, iris colour, and refractive error. BACKGROUND/AIMS Well dilated pupils make eye surgery easier.
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