Effects of experimentally induced ametropia on the morphology and optical quality of the avian crystalline lens

PURPOSE. TO examine the effects of refractive error on avian lens morpholog y and optical quality. METHODS. Hatchling white leghorn chicks were unilaterally goggled for 7 day s with either a form-deprivation goggle (n = 12), a -10 D defocus goggle Oz = 12), or a +10 D defocus goggle (n = 12) to induce myopia and hyperopia. Optical quality of lenses (focal length and focal length variability) from treated and contralateral control eyes was assessed using a scanning laser apparatus. Lens morphology was examined by light and electron microscopy. RESULTS. Although the induction of refractive errors did not significantly alter lens size, shape, paraxial focal length, or average focal length, ave rage focal length variability increased. Lenses from eyes goggled with form -deprivation and +10 D defocus goggles demonstrated a twofold increase in a verage focal length variability, when compared with their contralateral con trols. The morphology of the lens is not altered by these experimental mani pulations. CONCLUSIONS. This study provides evidence that the refractive development o f the chick lens is not independent of the refractive development of the oc ular globe and that chick lenticular development is influenced by both gene tics and visual experience.