Short-term effects of low-concentration atropine eye drops on pupil size and accommodation in young adult subjects

Abstract

Purpose: A single eye drop containing 0.01% atropine every evening has previously been found to inhibit myopia progression in young adults. We have tested the short-term effects of very low-dose atropine eye drops on pupil sizes and accommodation in young adult subjects.

Methods: Fourteen eyes of young adult subjects participated in the clinical observation. A single eye drop was applied with concentrations of either 0.01%, 0.005%, or 0.001% in the evening. Baseline parameters were measured before atropine application. Changes of pupil sizes, under photopic and mesopic conditions, as well as accommodation amplitudes were observed over the next day and analyzed by paired the Wilcoxon signed-rank test.

Results: The pupil was significantly dilated 12 h after instillation of 0.01% atropine eye drops, both under photopic (3.3 ± 0.5 mm vs. 4.9 ± 0.9 mm) and mesopic (4.8 ± 0.7 mm vs. 6.1 ± 0.7 mm) conditions. Pupil sizes recovered over the day but were still significantly larger in the evening, compared to the baseline parameters measured on the day before (3.9 ± 0.5 mm vs. 5.3 ± 0.6 mm). The subjective near point of accommodation was reduced from 8.0 ± 2.4 to 6.6 ± 2.8 dpt in the morning and to 7.0 ± 2.9 dpt in the evening. At 0.005%, the pattern of results remained still similar, although the magnitude of the effects was generally smaller. At 0.001%, pupil sizes were still weakly significantly larger in the morning.

Conclusions: At a dose of 0.01%, clinically significant short-term effects were detected on pupil size and accommodation for at least 24 h. At the lowest dose of 0.001%, only tiny effects on pupil size were detectable.

Keywords: Accommodation; Atropine; Eye drops; Myopia; Pupil size.

Fig. 1

Pupil sizes on the day before and the day after instillation of 0.01% atropine eye drops under photopic and mesopic conditions. The edges of boxes indicate 25th percentile, median, and 75th percentile, and whisker displays the minimal and maximal values. *p ≤ 0.001, statistically significant differences to pupil size without atropine eye drops

Fig. 2

Baseline pupil sizes on the day before atropine application, on the day after application in the morning, at noon, and in the evening under photopic (left) and mesopic (right) conditions. a 0.01% atropine. b 0.005% atropine. c 0.001% atropine. Note that pupils were clearly dilated after atropine application in the morning of the observation day both at 0.01% and, less so, at 0.005% atropine, but not with 0.001%. Note also that the effect declined about over the day (most clearly seen in a, photopic conditions). The edges of boxes indicate 25th percentile, median, and 75th percentile, and whisker displays the minimal and maximal values. Dots represent statistical outlier. *p ≤ 0.05, statistically significant differences to pupil size without atropine eye drops

Fig. 3

a Effects of low-dose atropine on near-point accommodation at doses of 0.01%, 0.005%, and 0.001% atropine. The edges of boxes indicate 25th percentile, median, and 75th percentile, and whisker displays the minimal and maximal values. Dots represent statistical outlier. *p ≤ 0.05, statistically significant differences to pupil size without atropine eye drops. b Exemplified dynamic pupillometry without and after application of 0.01% atropine eye drops. Procedure: 2 s mesopic, followed by 2 s photopic, followed by relaxation under mesopic conditions

Fig. 4

Diurnal variations in pupil size under photopic and mesopic conditions. No changes were observed over the day. The edges of boxes indicate 25th percentile, median, and 75th percentile, and whisker displays the minimal and maximal values. Dots represent statistical outliers