Abstract
Purpose To examine the interaction between a short period of hyperopic defocus and low-dose atropine upon the choroidal thickness and ocular biometrics of healthy myopic subjects. Methods Twenty young adult myopic subjects had subfoveal choroidal thickness (ChT) and ocular biometry measurements taken before and 30 and 60 min following the introduction of optical blur (0.00 D and −3.00 D) combined with administration of 0.01% atropine or placebo. Each combination of optical blur and drug was tested on different days in a fixed order. Results The choroid exhibited significant thinning after imposing hyperopic defocus combined with placebo (mean change of −11 ± 2 μm, p < 0.001). The combination of hyperopic blur and 0.01% atropine led to a significantly smaller magnitude of subfoveal choroidal thinning (−4 ± 8 μm), compared to placebo and hyperopic defocus (p < 0.01). Eyes treated with 0.01% atropine with no defocus exhibited a significant increase in ChT (+6 ± 2 μm, p < 0.01). Axial length also underwent small but significant changes after treatment with hyperopic blur and placebo and 0.01% atropine alone (both p < 0.01), but of opposite direction to the changes in choroidal thickness. However, the 0.01% atropine/hyperopic blur condition did not lead to a significant change in axial length compared to baseline (p > 0.05). Conclusion Low-dose atropine does inhibit the short-term effect of hyperopic blur on choroidal thickness and, when used alone, does cause a slight thickening of the choroid in young healthy myopic adults.
Highlights
Myopia is one of the most common types of refractive error and a leading cause of functional visual loss [1]
Clinical trials examining various myopia control interventions indicate that muscarinic blockers appear to have the strongest preventative effect on myopia progression [2,3,4,5]
It is worth noting that there was a discrepancy between the refractive error and axial length data for low-dose atropine in this study, with the axial elongation observed in the 0.01% atropine group appearing comparable to that observed in the placebo control group [15]
Summary
Myopia is one of the most common types of refractive error and a leading cause of functional visual loss [1]. An important observation from the ATOM 2 study showed that low-dose (0.01%) atropine is almost as effective as higher concentrations (0.5%, 0.25%, and 0.1%) of atropine in slowing the progression of the spherical equivalent refraction (SEQ) of myopia while causing less visual side effects [8]. E current clinical trial (LAMP) has shown the ability of different concentrations of low-dose atropine (0.05%, 0.025%, and 0.01%) to slow myopia progression in myopic children, with 0.05% atropine being the most effective in controlling axial length and SEQ progression [17]. The practical question remains whether low-dose atropine (0.01%) can inhibit short-term changes in choroidal thickness and axial length in response to hyperopic defocus. By investigating ocular changes after combined interventions, we hoped to improve our understanding of the myopigenic mechanisms influencing the thickness of the choroid in humans and provide insights into the possible mechanism underlying the myopia control effects of low-dose atropine
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