Short-term effects of atropine on the retina and choroid in young adults

Low concentration atropine is widely prescribed to slow myopia progression in children, yet its short-term retinal and choroidal effects remain incompletely understood. This study aimed to evaluate short-term effects of a range of low atropine concentrations on axial length, retinal and choroidal thickness, and microvasculature.

In this double-masked, randomized study, twenty healthy adults received a single instillation of placebo, 0.01%, 0.025%, 0.05%, or 0.1% atropine in the right eye across five separate sessions. Retinal and choroidal thickness in the central 1.0 mm diameter and 1.0-3.0 mm annulus, perfusion density in the superficial and deep vascular complex and choriocapillaris in the central 1.0 mm and 1.0-2.5 mm annulus, foveal avascular zone and axial length were assessed at baseline and 1 h and 24 h after instillation.

Participant mean age was 25.5 ± 3.4 years and mean refraction was - 1.9 ± 2.2 D. No significant changes in retinal or choroidal thickness or axial length were observed for any concentration or time point (P > 0.05). The superficial vascular plexus perfusion density in the 1.0-2.5 mm annulus showed significant decrease (P = 0.02) with time after atropine instillation, but not with concentration (P > 0.05); post hoc analysis showed significant decrease from baseline at 1 h (P = 0.03) compared to 24 h (P = 0.28).

These findings indicate that a single instillation of 0.01%-0.1% atropine does not alter axial length or retinal or choroidal thickness over 24 h, but may transiently affect superficial retinal perfusion in a time-dependent manner. Characterizing these short-term effects is important for a better understanding of the physiological responses to atropine in clinical and research settings.