Effect of 0.025% atropine on ocular biometry changes during accommodation.

Purpose: Low concentration atropine is an effective treatment to slow myopia progression and axial elongation and also reduces accommodation. On-axis ocular dimensions of the eye change during accommodation; hence, this study aimed to quantify the effect of 0.025% atropine eye drops on accommodation-induced changes in ocular biometry.

Methods: Twenty-eight myopic participants with a mean (SD) age of 17.0 (6.0) years (range: 8.0-25.5 years) and spherical equivalent refraction (SER) of -2.03 (1.05) D (range: -0.75 to -4.38 D) were enrolled. Baseline ocular biometry measurements of the left eye were captured using an optical biometer (Zeiss IOLMaster 700) for 0, 2, 4 and 6 D accommodation stimuli, presented via a Badal optometer. The accommodation response (AR) was determined using wavefront aberrometry (Imagine Eyes irx3) for the same accommodation stimuli and following cycloplegia using 1% tropicamide. Participants instilled 0.025% atropine eye drops nightly for 1 week in both eyes, and ocular biometry measurements were repeated on the day after the final atropine dose.

Results: Anterior chamber depth (ACD) and corrected vitreous chamber depth (cVCD) decreased, and crystalline lens thickness (LT), anterior segment length (ASL), crystalline lens centre position (LCP) and the AR increased significantly during accommodation (all p ≤ 0.009). Accommodation-induced changes in ACD and LT were reduced following 0.025% atropine use (both p ≤ 0.01), with significant pre- and post-atropine differences for the 4 and 6 D stimuli (all pairwise comparisons, p ≤ 0.004). On average, ACD, ASL and LCP increased, while cVCD, corrected axial length (cAL), and the AR decreased following 1 week of 0.025% atropine use (all p ≤ 0.002).

Conclusions: The AR and on-axis ocular biometric changes during accommodation were reduced following 1 week of 0.025% atropine use. These findings may have implications for the association between near work and myopia, and atropine's mechanism of action in humans.