Development of the refractive state in eyes of ostrich chicks (Struthio camelus)

Objective-To follow the development of the refractive error in the eyes of ostrich chicks from age 0 to day 37 after hatching. Animals-35 ostrich chicks. Procedures-Spot retinoscopy was conducted to assess refractive error in ost rich chicks. Seventy eyes of 35 ostrich chicks were examined. Of these, 18 chicks were followed over time. At least 4 serial measurements (at 2- to 7- day intervals) were conducted in each of these chicks from day 1 to 37 aft er hatching. Seventeen additional chicks were examined on days 0, 3, 12, an d 19 after hatching. Results-Ostrich chicks were myopic at hatching, with a mean +/- SD refracti ve error of -4.47 +/- 0.15 diopters (D). The refractive error rapidly decre ased during the first week of life, and by day 7 after hatching, chicks wer e slightly hyperopic, with a mean refractive error of 0.42 +/- 0.12 D. Afte r day 7, there were no significant differences in the mean refractive error . Conclusions-The development of optics in the ostrich eye appears to be uniq ue among animals and is characterized by myopia at hatching, rapid onset of emmetropia, and minimal variation in refractive error among chicks.