Abstract
Myopia is a major public health problem, affecting one third of the population over 12 years old in the United States and more than 80% of people in Hong Kong. Myopia is attributable to elongation of the eyeball in response to defocused images that alter eye growth and refraction. It is known that the retina can sense the focus of an image, but the effects of defocused images on signaling of population of retinal ganglion cells (RGCs) that account either for emmetropization or refractive errors has still to be elucidated. Thorough knowledge of the underlying mechanisms could provide insight to understanding myopia. In this study, we found that focused and defocused images can change both excitatory and inhibitory conductance of ON alpha, OFF alpha and ON–OFF retinal ganglion cells in the mouse retina. The firing patterns of population of RGCs vary under the different powers of defocused images and can be affected by dopamine receptor agonists/antagonists’ application. OFF-delayed RGCs or displaced amacrine cells (dACs) with time latency of more than 0.3 s had synchrony firing with other RGCs and/or dACs. These spatial synchrony firing patterns between OFF-delayed cell and other RGCs/dACs were significantly changed by defocused image, which may relate to edge detection. The results suggested that defocused images induced changes in the multineuronal firing patterns and whole cell conductance in the mouse retina. The multineuronal firing patterns can be affected by dopamine receptors’ agonists and antagonists. Synchronous firing of OFF-delayed cells is possibly related to edge detection, and understanding of this process may reveal a potential therapeutic target for myopia patients.
Highlights
The World Health Organization (WHO) report estimated that over 50% of the global population will have myopia by 2050 [1]
The results suggested that defocused images induced changes in the multineuronal firing patterns and whole cell conductance in the mouse retina
Recorded retinal ganglion cells (RGCs) were classified based on their light-evoked activities to square wave stimuli (525 nm full field; I = 1311 photoisomerizations per rod per second, (Rh*/rod/sec); 1 s stimulation, 5 s interval)
Summary
The World Health Organization (WHO) report estimated that over 50% of the global population will have myopia by 2050 [1]. The eye is relatively long for the optical power of the cornea and lens, resulting in distant images focusing in front of the photoreceptors. The induction of form-deprivation myopia by goggle wearing or lid suturing in chick [6,7], tree shrew [8], mouse [9] monkey and marmosets [10,11] had demonstrated visual feedback in eye growth control. Both monkeys [10] and chicks [12] developed
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