The Effects of Atropine on the Development of Binocular and Monocular Lens-Induced Myopia in Marmosets

Abstract

Purpose : Topical low-dose atropine has been identified as a possible drug treatment to reduce myopia progression in children, although there remain questions about the dosing and mechanisms of action. In this study we present preliminary evidence of atropine effects on the development of experimental myopia in marmosets.

Methods : Marmosets wore -5D single vision soft contact lenses either binocularly (n=15) or monoculary (OD -5D, OS plano, n=7) from 70 days of age for 10 weeks while being treated monocularly on the right eye with 1%, 0.1%, or 0.005% atropine (vehicle drops on left eyes). On-axis vitreous chamber depth (VC) and refractive state (Rx) were measured and compared interocularly, and also to monocularly treated -5D marmosets without atropine (n=8) and untreated marmosets (n=14).

Results :
Rearing marmosets with binocular -5D contact lenses induced significantly greater Rx and VC compensatory changes than treating them monoculary (overall Rx and VC change on treated eyes at the end of treatment, mean±SE: binocular group –6.76±1.50D, 0.85±0.13mm; monocular group -2.93±1.56D, 0.65±0.10mm, p<0.001). Atropine 1% effectively eliminated the response to monocular -5D lenses seen in non-atropine treated marmosets. Unlike the significant induced axial myopia seen in non-atropine eyes (interocular VC difference: 0.13±0.05mm, Rx difference: –2.81±0.74D, p<0.05), there were no interocular differences in VC or Rx at any ages tested in atropine treated marmosets (Repeated ANOVA Rx, p=0.23; VC p=0.35). However, low dose atropine (0.005% and 0.01%) was ineffective in reducing axial myopia in the binocular -5D lens reared marmosets (overall VC change at the end of treatment for 0.01% atropine; OD:0.85±0.05mm, OS:0.87±0.04mm, p=0.68; 0.005% atropine; OD: 0.84±0.05mm, OS:0.81±0.04mm, p=0.30)

Conclusions : The compensatory response to imposed hyperopic defocus is greater in binocularly treated marmosets suggesting interocular interactions in the visual control of emmetropization. Atropine at higher doses blocked lens imposed myopia by reducing axial growth in monocular treatments where less myopia was produced. Lower doses were not effective in reducing myopia at higher rates of development in binocularly treated animals.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.