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

Abstract Background 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. Methods 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. Results 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). Conclusion 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.