Background Pax-6 gene plays an important role in the process of eye development. This study was to determine the role of pax-6 in the axial myopia produced by hyperopic optical defocus and form deprivation in infant monkeys Methods Among seven normal infant rhesus monkeys (aged 1 to 1 5 months), five wore -3 00 D spectacle lenses over their right eyes and zero-powered lenses over their left eyes Monocular form deprivation was produced by eyelid fusion in two monkeys Ten weeks later, the monkeys were sacrificed by an overdose of barbiturates and their eyes were removed immediately A 5 mm×5 mm button of retina and sclera was taken from the posterior poles along with a 4-mm optic nerve RNA was isolated separately from each of these three types of tissues After that, reverse transcription polymerase chain reaction (RT-PCR) was used for determining gene expression in the retina, sclera and optic nerve Semi-quantitative analyses were performed on the PCR products Results As expected, the optically induced hyperopic defocus and the form deprivation produced myopic growth For the lens-treatment monkeys, pax-6 gene expression in the retinas of the defocused eyes was significantly higher than in the retinas of the left eyes ( t =5 703, P =0 005) However, there were no analogous significant differences between pax-6 expression in the scleras or the optic nerves For the two form-deprived monkeys, there were no obvious differences in pax-6 gene expression in the retinas or the optic nerves Conclusion The result that the expression of pax-6 was enhanced by hyperopic defocus in the infant monkey retina suggests that pax-6 may be involved in vision-dependent eye growth and emmetropization Background Pax-6 gene plays an important role in the process of eye development. This study was to determine the role of pax-6 in the axial myopia produced by hyperopic optical defocus and form deprivation in infant monkeys Methods Among seven normal infant rhesus monkeys ( aged 1 to 1 5 months), five wore -3 00 D spectacle lenses over their right eyes and zero-powered lenses over their left eyes Monocular form deprivation was produced by eyelid fusion in two monkeys Ten weeks later, the monkeys were sacrificed by an overdose of barbiturates and their eyes were removed immediately A 5 mm × 5 mm button of retina and sclera was taken from the posterior poles along with a 4-mm optic nerve RNA was isolated separately from each of these three types of tissues After that, reverse transcription polymerase chain reaction (RT-PCR) was used for determining gene expression in the retina, sclera and optic nerve Semi-quantitative analyzes were performed on the PCR products Re sults As expected, the optically induced hyperopic defocus and the form deprivation produced myopic growth For the lens-treatment monkeys, pax-6 gene expression in the retinas of the defocused eyes was significantly higher than in the retinas of the left eyes (t = 5 703, P = 0 005) However, there were no analogous significant differences between pax-6 expression in the scleras or the optic nerves For the two form-deprived monkeys, there were no obvious differences in pax-6 gene expression in the retinas or the optic nerves Conclusion The result that the expression of pax-6 was enhanced by hyperopic defocus in the infant monkey retina suggests that pax-6 may be involved in vision-dependent eye growth and emmetropization