Intraocular pressure and eye enlargement in chicks

In chicks, the application of optical devices that blur vision results in eye enlargement and ametropia. The research presented here investigated changes in intraocular pressure (IOP), specifically intravitreal pressure, that occur with eye enlargement induced by this means. Plastic goggles (domes) were glued over one eye in 25 domestic chicks. Plastic rings were glued around one eye in 25 control chicks to control for the mechanical effects of the treatment but which left their vision undisturbed. Following two weeks of treatment, domes and rings were removed and IOP was measured. Mean IOP of the domed eyes was 1.14 mm Hg lower than that of control eyes, a difference that was not statistically significant. The eyes of an additional group of 20 chicks that experienced similar treatments were refracted; these refractions revealed that the dome-treated eyes had a mean refractive state that was 7.98 D myopic relative to the ring controls, which was statistically significant. The results indicate that IOP does not change significantly in chicks with experimental eye enlargement induced by retinal-image degradation.