Single Low-Dose Atropine Drop Affects Pupils for 24 Hours, Study Finds

Researchers at the University of Houston have reported that a single low-dose atropine eye drop (0.01%–0.1%) produces changes in pupil size and focusing ability that persist for at least 24 hours, with no observable short-term structural changes to the eye.

Study Design and Methodology

The double-masked, randomized study, published in the journal Eye and Vision, involved 20 healthy adult participants. Each participant received a single instillation of either a placebo or atropine in the right eye across five separate sessions.

Researchers measured eye structure, thickness, and length in the central retina one hour and 24 hours after administration.

Key Findings

Pupil and focusing effects: Changes in pupil size and focusing ability were observed to persist for at least 24 hours after a single drop.

Structural measurements: No alterations in axial length or retinal and choroidal thickness were recorded over the 24-hour period.

Vascular changes: Temporary changes in superficial retinal perfusion were noted, described as time-dependent.

Context and Previous Research

Low-concentration atropine is commonly prescribed to slow myopia progression in children. The study was led by Professor Lisa Ostrin and postdoctoral researcher Barsha Lal at the University of Houston. Ostrin's prior research had documented similar effects on pupil size from a single atropine drop.

This study is part of a broader research effort, including a $25 million National Institutes of Health-funded clinical trial co-led by David Berntsen at the University of Houston, aimed at delaying the onset of myopia in children.

Researcher Statements

Professor Lisa Ostrin stated: "These findings indicate that a single instillation of atropine does not alter axial length or retinal or choroidal thickness over 24 hours but may transiently affect superficial retinal perfusion in a time-dependent manner."

Ostrin added: "Characterizing these short-term effects is important for a better understanding of the physiological responses to atropine in clinical and research settings."