Abstract
Abstract: :
Purpose: Previously, we have shown that lens induced myopia interferes with the emmetropization of higher–order monochromatic aberrations during growth for a constant pupil size. Here we explore the effect of removing the goggle on day 7 and follow these eyes up to day 14. Methods: On the first day post–hatching, 10 chicks were unilaterally fitted with minus 15D goggles. On day 7, the goggles were removed (ungoggled eye). The other eye acted as a control (control eye). Hartmann–Shack (HS) wavefront measurements (633nm light) and retinoscopy were performed on days 7, 8, 9, 11, and 14. A separate group of 7 birds remained unilaterally goggled beyond day 7 (goggled eye). In these birds the goggles were removed for brief periods of time for HS measurements. HS images chosen for analysis corresponded to larger pupils and were presumed to be unaccommodated. All HS images were analyzed for a constant pupil diameter of 1.6mm. Results: On day 7, immediately following removal of the goggle, higher–order root mean square wavefront error and amount of astigmatism were significantly (p=0.04 and p=0.004) larger in the ungoggled (and goggled eyes) than in control eyes. On day 7, the aberrations and amount of astigmatism of the goggled and ungoggled eyes did not differ significantly. Aberrations of the eyes that remained goggled decreased significantly after day 7. Between days 7 and 9 the amount of astigmatism and the aberrations of the ungoggled eyes also decreased significantly (p=0.015 and p=0.003). There was no significant difference between the ungoggled and control eyes in the amount of astigmatism and the aberrations by days 8 and 9 respectively and they remained not significantly different on day 14. On day 9, however, the aberrations and amount of astigmatism of the ungoggled eyes were significantly (p=0.001 and p=0.046) lower than the goggled eyes. The aberrations of the goggled and ungoggled eyes were not significantly different on day 14, but the amount of astigmatism was significantly (p=0.003) smaller in the ungoggled eyes. Control eyes for each group of birds were not significantly different in aberrations or the amount of astigmatism on days 7 and 14. Conclusions: Lens induction of myopia causes changes in the optical components of the treated eye relative to the control eye. When eyes are allowed to recover from lens induced myopia, the aberrations and amount of astigmatism in these eyes emmetropize. Following goggle removal, higher–order aberrations emmetropize faster than in eyes that remain goggled.
Keywords: myopia • optical properties • astigmatism