The aim of this study was to compare the changes of diplopia and enophthalmos in patients with blowout fractures. Three hundred sixty-two patients who presented with blowout fractures between March 2006 and February 2011 were analyzed. The sequential time changes of diplopia and enophthalmos were measured in the operated group and the observed group according to (1) the duration of preoperative observation (early: within 7 days, late: 8-14 days, delayed: >15 days); (2) the defect size (minimal: <1 cm(2), small: 1.1-2.0 cm, medium: 2.1-3.0 cm(2), large: >3.0 cm(2)); and (3) the age of the patients (<20, 21-40, 41-60, >61 years).Among the 362 patients, 242 (66.9%) had an operation, and 120 (33.1%) did not. The duration of preoperative observation did not affect the postoperative diplopia or enophthalmos. There were significant differences of enophthalmos among the operated groups with a different defect size at the preoperative period (P = 0.036 [Pearson χ(2)]). There were significant differences of diplopia among the operated groups with different defect sizes at the 6 months' follow-up period (P = 0.014 [Pearson χ(2)]). The diplopia in the older age group (>60 years) was significantly greater than that of the other 3 groups at 6 months (P = 0.023) and at 12 months (P = 0.023, [Pearson χ(2)]).We think surgery should be delayed until the swelling is decreased unless the medial rectus muscle is incarcerated. We also think that the defect size is not an important factor for whether to perform surgery. We think that the reason for the greater diplopia in the older age group is that the adaptation of binocular convergence is decreased in the older age group.