Broadband Long Wavelength Light Promotes Myopic Eye Growth and Alters Retinal Responses to Light Offset in Chick.

Purpose: Prolonged exposure to broadband light with a short-wavelength (blue) or long-wavelength (orange/red) bias is known to impact eye growth and refraction, but the mechanisms underlying this response are unknown. Thus, the present study investigated the effects of broadband blue and orange lights with well-differentiated spectrums on refractive development and global flash electroretinography (gfERG) measures of retinal function in the chick myopia model.

Methods: Chicks were raised for 4 days with monocular negative lenses, or no lens, under blue, orange, or white light. Chick weight, eye dimensions, and refraction were measured at the conclusion of rearing. In a separate cohort of chicks, the effect of 4 days of colored light rearing on retinal responses to orange, blue, or white light flashes was assessed using gfERG.

Results: Chicks reared under orange light for 4 days exhibited a significantly larger myopic shift in response to negative lenses compared to those reared under blue light. Orange light rearing for 4 days increased the gfERG d-wave amplitude and implicit time in response to orange light flashes but did not alter responses to white or blue flashes. Blue and white light rearing did not affect the retina's response to light flashes of any color.

Conclusions: Orange light rearing exacerbated defocus-induced myopia relative to blue light rearing. The gfERG recordings revealed that prolonged orange light exposure increased retinal responsivity to the offset of long wavelength light flashes, suggesting a potential role for ON/OFF pathway balance in generating the refractive response that requires further electrophysiological and molecular investigation.