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Alexandra Benavente-Perez, Ann Nour, Eric R Ritchey, David Troilo; Effectiveness of Low-dose Atropine on the Marmoset Eye. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2155. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Low dose atropine (0.5%, 0.1% and 0.01%) has been shown to reduce myopia progression in humans by up to 24.5% (0.01%) to 40% (0.5%). The purpose of this study was to develop reliable measures to evaluate the effects of low doses of atropine on marmoset eyes for studies of myopia control.
Nine age-matched young adult marmosets were divided into three treatment groups of low-dose atropine (0.1%, 0.01% or 0.005%). Subjects received one drop of atropine in one eye. The contralateral eye served as control. Pupil diameter (PD) under fixed background illumination (254lux) and pupillary light reflex (PLR) to ophthalmoscope illumination were monitored at baseline and after atropine every 5mins for the first 30mins, every hour for the first 9hrs, and daily for 7 days. The accommodative response to 1D of imposed hyperopic defocus was measured with a Shin-Nippon autorefractor in one marmoset from each group for 5 days following the atropine drop.
The interocular PD difference, normalized to baseline, reached maximum at 4hrs (0.1%), 3hrs (0.01%) and 2hrs (0.005%) after instillation (+1.96±0.26mm,+1.46±0.28mm and +1.45±0.49mm respectively). PDs returned to baseline levels 6 (0.1%) or 7 days (0.01% and 0.005%) after instillation. The PLR was blocked 15 to 25mins after 0.1% instillation and recovered after 2 days, but was always present for the 0.01% and 0.005% dosages. Accommodation was reduced 3hrs after instillation of 0.1% and recovered after 4 days (baseline accommodation: 1.11±0.56D; 3hrs post: 0.05±1.08D, p=0.03; 4days post: 1.45±1.20D, p>0.05). Lower doses of atropine did not block the accommodative response (p>0.05).
A single drop of atropine had measurable effects on pupil function lasting several days and showed a dose response. Only the highest dose tested affected accommodation. While the effects of extended treatment have yet to be examined, these results will help guide further investigation of the effects of low-dose atropine for myopia control using the marmoset model.
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