Abstract
Abstract: :
Purpose: The common marmoset, Callithrix jacchus, is used as an animal model in studies of refractive error development. Our previous measurements of optical quality in marmosets (ARVO 2003) were performed on anesthetized animals in which the tear film quality may not have been optimal. In this study, we examined wavefront aberrations in awake marmosets. Methods: Measurements were made on both eyes of 19 marmosets whose ages ranged from 36 to 452 days. All subjects were members of a study of emmetropization; nine of the subjects had been treated with monocular diffusers or occluders while the remaining animals had worn binocular negative spectacle lenses. Four of the lens–treated animals were tested prior to treatment. Abberations were measured on awake, cyclopleged animals using a clinical Hartmann–Shack wavefront sensor (COAS, Wavefront Sciences). The subject was held in front of the device and centroid pattern images were captured when the eye appeared aligned in a live video image. Captured images were analyzed if the centroid patterns were centered and alignment was judged to be good by inspection of the video frame. Wavefront error was expressed as a 7th order Zernike polynomial expansion. Results: The average RMS wavefront error for 3rd order and higher terms was 0.15 micron (s.d.= 0.06 micron) for a 3 mm diameter pupil, which is about half the value we obtained previously in anesthetized animals. Wavefront aberration decreased with age in both treated and untreated eyes. In the youngest eyes, spherical aberration tended to be negative and became less negative or even positive with age. The aberrations of lens–treated eyes did not differ appreciably from those of age–matched untreated eyes. Interocular analysis of the monocularly form–deprived animals indicated that RMS aberration was significantly higher in the more myopic eye in the 4th order (p = 0.03), 5th order (p = 0.04) and 6th order (p = 0.01) terms. Conclusions: The improvement in optical quality of the awake marmoset eye is probably due to the improved tear film quality. The optical quality of the awake marmoset eye is comparable to our measurements on human eyes with 4 to 5 mm pupils. Our preliminary results indicate that higher order aberrations increase in myopic eyes of monocularly form–deprived animals.
Keywords: optical properties • emmetropization • refractive error development