The effect of intravitreal injection of atropine on the proliferation of scleral chondrocyte in vivo.

Atropine was found to be effective in arresting the progression of myopia. However, the actual mechanism is still unclear. Thus, we tried to investigate the in vivo effect of atropine on the proliferation of scleral chondrocytes in chicks of form-deprivation myopia. Twenty chicks were equally divided into 4 groups which included intravitreal injection of normal saline (IVN), IVN with goggling (IVNG), intravitreal injection of atropine (1%) (IVA), and IVA with goggling (IVAG) groups. Intravenous injection of bromodeoxyuridine (BrdU) (30 mg/kg) from subaxillary vein was performed 2 hours before being sacrificed. The eyeballs were then fixed in 10% neutral-buffered formalin at 4 degrees C. Standard BrdU immunohistochemical staining was performed. The BrdU labeling index was obtained from the average of positive labelings of BrdU in scleral chondrocytes for every 100 counting cells in posterior poles and anterior scleral margins by two experienced technicians. The BrdU index on the anterior scleral margin of the IVAG group was less than that of the IVNG group. The index on the anterior scleral margin of the IVNG group was higher than the IVN group. Although the index on the posterior poles of the IVNG group was also higher than the IVN group, it was statistically not different. Also, no statistical difference was found between IVN and IVA on the anterior scleral margins or posterior poles. The index was significantly different on the anterior scleral margins, but not on the posterior pole among each group. Therefore, intravitreal injection of atropine could inhibit the proliferation of chondrocytes on the anterior margins of sclera, but not the posterior poles in form-deprivation myopia.