Abstract
Purpose: :
Ambient light intensity regulates the development of refraction in chicks reared under continuous light (Cohen et al., 2008). Form deprivation, such as via lid suturing, induce a refractive error in chicks' eyes. We examined the combined effect of light intensity and lid suture on the evolution of the refractive changes in chicks reared under continuous light.
Methods: :
Chicks with monocular lid suture were reared under 24-h lighting at three different light intensities: 10 000 lux (n = 12), 1000 lux (n = 9), and 50 lux (n = 11). A control group was reared under light dark cycle with light intensity of 1000 lux (n=10). Their eyes underwent repeated retinoscopy and keratometry, as well as ultrasound measurements.
Results: :
Light intensity was correlated with chicks' refraction and ocular parameters in the lid sutured eyes (r= 0.4-0.7). On day 90 after hatching, the exposure of the lid sutured eye to light intensities of 10 000, 1000 and 50 lux respectively developed hyperopia of +12.8 ± 4.1 diopters (D), +8.8 ± 2.3 D and +6.2 ± 3.6 D, and corneal refractive power of 42.5 ± 1.6D, 45.6 ± 3.3D and 47 ± 4.1D. Axial length in the three groups differed significantly, ranging from 16.5 ± 0.6 mm at 10 000 lux to 15.6 ± 0.9 mm at 50 lux. The refraction of the opened fellow eye was less hyperopic then the refraction of the lid sutured eye in all examined groups.
Conclusions: :
Under continuous light, ambient light intensity affect the development of chicks' refraction and ocular shape in a monocular lid sutured eye. Thus, we suggest that light intensity dependent regulation of chicks' ocular development is at least partially independent from a form vision.
Keywords: hyperopia • refractive error development • myopia