Studies on Refractive Changes in Chickens with Myopia Induced by Concave Lenses

Purpose To study the refractive changes in chickens with myopia induced by concave lenses of different dipoter and form deprivation. Methods 2-day-old chickens wore monocular concave lenses of - 5D, - 10D, - 20D and translucent occluders. Three weeks later, refraction was determined by streak retinoscopy and axial length was measured by A-scan. Results All experimental eyes showed myopia. The magnitude of the myopia almost approached the power of the lenses applied in - 5D and - 10D groups. The - 20D lenses caused similar amout of myopia as that of occluders. The axial length in all experimental eyes was longer, compared with the control eyes. Conclusion Concave lenses could alter eye growth and refractive status of chickens. Optical defocus imposed by concave lenses could be completely compensated by chickens in a limited range.