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Pauline Kang, Stefanie Clendaniel, Anne Li, Cindy Van, Xiaoying Zhu, David Troilo, Alexandra Benavente-Perez; Atropine applied at different times of day has different effects on choroid thickness. Invest. Ophthalmol. Vis. Sci. 2018;59(9):693. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether the time of day atropine is applied to the eye has different effects on choroid thickness in young adults, which is known to vary with a diurnal rhythm
Thirty-one adults (10M, 21F; 25±4 years) at 2 clinical sites (SUNY Optometry, USA and UNSW, Australia) were recruited for this study. Diurnal changes in subfoveal choroid thickness (sCT) were measured using Heidelberg Spectralis OCT. Baseline (BL) measures were first obtained every 4hrs for 12hrs throughout the day (8am, 12pm, 4pm, 8pm). Subjects were then randomized to 1 drop of 1% atropine in both eyes at either 8am or 8pm. Additional measures were made at 1, 12, 24, and 96 hrs following atropine application. After a 2-week wash out period, the protocol was repeated for the alternative instillation time (8am or 8pm), and the measurements were repeated.
The diurnal changes prior to atropine instillation showed that on average, BL sCT (270.24±80.17µm) decreased from 8am to 12pm by 24.41±91.36µm (p=0.005; adjusted p-value 0.0167) and returned back to BL thickness by 4pm (p=0.070; adjusted p-value 0.0167) and 8pm (p=0.042; adjusted p-value 0.0167).A moderate relationship between BL and change in sCT measured 1 hr after 8am atropine instillation was apparent; atropine prevented diurnal sCT thinning and thinner choroids tended to thicken 1 hr after 8am atropine instillation (R2=0.130, p=0.06). This relationship was not apprarent after 8pm atropine instillation (R2=0.118, p=0.162).
Confirming previous reports, diurnal changes in sCT was evident throughout the day from 8am to 8pm. In agreement with experiemental animal studies showing an influence of the BL sCT on response to defocus, the results of this study suggest that humans with thinner sCT have larger sCT responses after morning atropine 1% instillation. If sCT changes are to some extent involved in myopia control with atropine, the greater changes in sCT found in this study suggest that morning atropine instillation may exert greater myopia control effects.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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