Abstract
Abstract: :
Purpose: Previously, we reported that higher order monochromatic aberrations decreased in untreated chick eyes during growth for a constant pupil size. Differences between goggled and control eyes were significant. We wish to measure and compare monochromatic aberrations during growth in treated and control eyes during the experimental induction of myopia. We also assess the time course of the changes and whether the change in monochromatic aberrations with age is consistent with an active emmetropization process. Methods: On the first day post-hatching, chicks were unilaterally fitted with minus 15D goggles. The other eye acted as a control. On days 0, 1, 2, 4, and 7, goggles were removed for brief periods of time for Hartmann-Shack wavefront measurements (633nm light) and retinoscopy. Results for 17 chicks that developed refractive errors, consistent with the goggle power, were analysed. Hartmann-Shack images chosen corresponded to larger pupils and relaxed accommodation. Results: During growth of the ungoggled eye, for a fixed pupil size, root mean square (rms) of the higher order wavefront error decreased exponentially and significantly along with a reduction in second order defocus terms. For the maximum pupil size observed during wavefront measurements, the rms higher order aberrations increased significantly with age. The change in higher order monochromatic aberrations with age for treated eyes followed a different pattern. There was no significant decrease in overall higher order aberrations, or in 3rd or 4th order aberrations, for a fixed pupil size, with age. Analysis of differences between treated and control eyes suggests a rapid change in the differences in higher order aberrations following placement of the goggle on the eye. Conclusions: Lens induction of myopia causes changes in the optical components of the treated eye relative to the control eye. It interferes with the normal reduction of aberrations with age, suggesting that the decrease in aberrations is an active emmetropization process. The temporal relationships between these optical changes and myopia development require further investigation.
Keywords: emmetropization • animal model • optical properties