PURPOSE: To evaluate the asymmetry of bilateral orbital development in Chinese children with congenital microphthalmia and to provide a criterion for tailoring treatment timing and therapy. DESIGN: Retrospective cohort study. METHODS: By combining multisection helical computerized tomography imaging with a computer-aided design system, we measured 38 children between 0 and 6 years of age with congenital microphthalmia and 70 normal children of the same age group. Variables were measured, including orbital volume, depth, width, and height and eye all volume. Displacement of the orbital rims was calculated by mirroring the unaffected orbit across the mid sagittal plane of body. RESULTS: Significant differences were observed between the orbital volume, eyeball volume, orbital width, and orbital height of the affected and unaffected sides of children with congenital microphthalmia (P < .001). The difference between the orbital depth of the affected and unaffected sides was not significant (P = .055). Growth of the inferior and lateral rims retarded by an aye) age of 3 mm, whereas that of the medial and superior rim:, retarded by less than 1 mm. CONCLUSIONS: The amount of decrease in orbital volt me of children with congenital microphthalmia is related to the severity of the disease (decrease in size of the eye), rather than to age. Retarded orbital development is evident primarily in the inferior and lateral rims, cort elating mostly with zygomatic and then maxilla and frontal bone. The growth of the affected orbit slows down or even stagnates by 3 years of age. Intervention therapy before 3 years of age was critical. (Am J Ophthalmol 2012;154:601-609. (C) 2012 by Elsevier Inc. All rights reserved.)