The regulation of the scleral growth associated with deprivation myopia in chicks

The mechanism of axial elongation caused by experimental or clinical myopia is still unknown. We sought to explore the changes of scleral chondrocytes during myopia formation through the cell biology model. White Leghorn chicks were used for this study. The right eye was covered with a translucent goggle after hatching, and the left eye was left uncovered for control. The chicks were maintained on 12 hours light-dark cycle for two weeks, then sacrificed every other day and the eyeballs removed for study. Our results in the primary culture of scleral chondrocytes showed that the densities of chondrocytes on myopic eyes were significantly higher than those of the controlled non-myopic eyes, and 3H-thymidine incorporation rate also increased with the increasing of the concentration of fetal bovine serum. The PCNA index of chondrocytes in myopic eyes was also higher than that of the controlled non-myopic eyes. Thus, axial elongation of experimental myopia in the chick is the result of active tissue remodeling rather than passive scleral stretching alone.