Abstract
Low-dose atropine helps to control myopia progression with few side effects. However, the impact of atropine, a non-selective muscarinic Acetylcholine (ACh) receptor antagonist, on retinal ganglion cells (RGCs) remains unclear. After immersing the cornea and adjacent conjunctiva of enucleated eyes in 0.05% (approximately 800 μM) atropine solution for 30 min, the atropine concentration reached in the retina was below 2 μM. After direct superfusion of the retina with 1 μM atropine (considering that the clinical application of 0.05% atropine eye drops will be diluted over time due to tear flow for 30 min), no noticeable changes in the morphology of ON and OFF alpha RGCs (αRGCs) were observed. Atropine affected the light-evoked responses of ON and OFF αRGCs in a dose- and time-dependent fashion. Direct application of less than 100 μM atropine on the retina did not affect light-evoked responses. The time latency of light-induced responses of ON or OFF αRGCs did not change after the application of 0.05–100 μM atropine for 5 min. However, 50 μM atropine extended the threshold of joint inter-spike interval (ISI) distribution of the RGCs. These results indicated that low-dose atropine (<0.5 μM; equal to 1% atropine topical application) did not interfere with spike frequency, the pattern of synchronized firing between OFF αRGCs, or the threshold of joint ISI distribution of αRGCs. The application of atropine unmasked inhibition to induce ON responses from certain OFF RGCs, possibly via the GABAergic pathway, potentially affecting visual information processing.
Highlights
Myopia is a significant public health problem because high myopia increases the risk of severe eye diseases, including retinal detachment, glaucoma, and cataract
50 μM atropine extended the threshold of joint inter-spike interval (ISI) distribution of the retinal ganglion cells (RGCs). These results indicated that low-dose atropine (
This study evaluated the effects of topical administration of 0.05–500 μM atropine on αRGCs, a range that covered doses administered to humans, concentrations lower than 0.5 μM atropine did not alter the spike frequency, the synchronized firing pattern between OFF αRGCs, and the joint inter-spike interval (ISI) distribution threshold of RGCs
Summary
Myopia is a significant public health problem because high myopia increases the risk of severe eye diseases, including retinal detachment, glaucoma, and cataract. Myopia is a leading cause of blindness (Shih et al, 2006; Holden et al, 2014; Russo et al, 2014). It has been predicted that 50% of the world’s population will be myopic by 2050 (Holden et al, 2016). The Effect of Atropine on Retina over 80% of adults in Hong Kong and 22% of the global population (Vitale et al, 2008; Foster and Jiang, 2014). Despite its significant public health impact, myopia is arguably neither prevented nor reduced by any optical approaches to correct image defocus (Cooper and Tkatchenko, 2018)
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