AIM:To evaluate development of the ocular optical components and refractive error in premature infants and full term infants.·METHODS:Anterior chamber depth,lens thickness,and posterior segment length were measured by A-scan ultra-sonography in 218 premature infants and 76 full term infants 1,4,8,12 months after birth. The spherical equivalent refractive error was measured by cycloplegic retinoscopy 8,12 months after birth. ·RESULTS:Anterior chamber depth,posterior segment length and axial length were growing while the lens thickness decreasing with age;Anterior chamber depth,posterior segment length and axial length in premature infants were smaller than that of the full term infants at early age after birth; Posterior segment length and axial length showed greater increase in premature infants than full term infants; but no difference between the anterior chamber depth and the thickness of the lens. ·CONCLUSION:Optical components are immature at early age after birth but grow more rapidly with age in premature infants than that in full term infants,which contribute to the emmetropization development.