Synchronous myopia development induced by bilateral form deprivation in chicks.

Form deprivation (FD) is a widely employed experimental paradigm, typically used to induce unilateral myopia in animal models. This model is weakened by potential influence upon the FD eye from vision in the freely-viewing contralateral eye, which could be eliminated by imposing FD in both eyes; but while a few previous studies have explored the feasibility of inducing bilateral FD in chicks, substantial discrepancies in treatment outcomes were noted. Consequently, this study aimed to establish a bilateral FD myopia model in chicks, with validation by investigating the associated ocular growth patterns, feeding, and social behavior.

Changes in Expression in BMP2 and Two Closely Related Genes in Guinea Pig Retinal Pigment Epithelium during Induction and Recovery from Myopia.

Purpose: We previously reported differential gene expression of the bone morphogenetic protein 2 () in guinea pig retinal pigment epithelium (RPE) after 1 day of hyperopic defocus, imposed with a negative contact lens (CLs). The study reported here sought to obtain insights into the temporal profiles of gene expression changes in Bmp2, as well as those of two closely related genes, the inhibitor of DNA binding 3 (Id3) and Noggin (Nog), both during myopia induction and when the CL treatment was terminated to allow recovery from induced myopia.

Methods: To induce myopia, 2-week-old pigmented guinea pigs (New Zealand strain, n = 8) wore monocular -10 diopter (D) rigid gas-permeable (RGP) CLs for one week, while the other eye served as a control.

Experimentally induced myopia and myopic astigmatism alter retinal electrophysiology in chickens.

Myopia (or "short-sightedness") and astigmatism are major causes of visual impairment worldwide. Significant amounts of astigmatism are frequently observed in infants and have been associated with myopia development. Although it is well established that both myopia and astigmatism are associated with ocular structural changes from anterior to posterior segments, very little is known on how these refractive errors alter retinal functions.

Early Astigmatism Can Alter Myopia Development in Chickens.

Purpose: To determine the effects of optically imposed astigmatism on myopia development in chickens.

Methods: Chicks were randomly assigned to wear either spherical (-10D, "LIM", n = 14) or sphero-cylindrical lenses (n ≥ 19 in each group) monocularly for a week from 5 days of age. All lenses imposed the same magnitude of spherical-equivalent hyperopic defocus (-10D), with the two astigmatic magnitudes (-8D or -4D) and four axes (45°, 90°, 135°, or 180°) altered to simulate four subtypes of clinical astigmatism.