Long-wavelength (red) light produces hyperopia in juvenile and adolescent tree shrews

摘要

Graphical abstract Display Omitted Highlights ? Juvenile and adolescent tree shrews become hyperopic in narrow-band red light. ? The vitreous chamber is smaller than normal and the choroid is thicker. ? Tree shrews at these ages do not become hyperopic in response to a plus lens. ? The continuing response to red contrasts with the lack of response to a plus lens. ? The emmetropization mechanism can slow eye growth in juvenile and adolescent animals. Abstract In infant tree shrews, exposure to narrow-band long-wavelength (red) light, that stimulates long-wavelength sensitive cones almost exclusively, slows axial elongation and produces hyperopia. We asked if red light produces hyperopia in juvenile and adolescent animals, ages when plus lenses are ineffective. Animals were raised in fluorescent colony lighting (100–300 lux) until they began 13days of red-light treatment at 11 (n=5, “infant”), 35 (n=5, “juvenile”) or 95 (n=5, “adolescent”) days of visual experience (DVE). LEDs provided 527–749 lux on the cage floor. To control for the higher red illuminance, a fluorescent control group (n=5) of juvenile (35 DVE) animals was exposed to ～975 lux. Refractions were measured daily; ocular component dimensions at the start and end of treatment and end of recovery in colony lighting. These groups were compared with normals (n=7). In red light, the refractive state of both juvenile and adolescent animals became significantly (P