Levator muscle resection for simple congenital ptosis: its impact on preoperative levator function and dose-response ratio.

OBJECTIVE

The primary aim of this study is to calculate the dose-response ratio in patients with different levels of levator function following levator resection in simple congenital ptosis. The secondary outcome is to evaluate the success rate and effect of levator resection on postoperative levator function.

METHODS

In a retrospective study, the medical records of patients were reviewed for age, gender, laterality, preoperative and postoperative measurements (palpebral fissure height, marginal reflex distance 1, and levator function), magnitude of levator resection, follow-up time, and postoperative complications.

RESULTS

Of 154 patients with a mean age of 17.12 ± 11.14 years, 54 patients had excellent levator function, 41 had good function, and 59 had fair function. Following surgery, the mean levator function increased from 8.81 ± 3.40 mm to 11.29 ± 3.25 mm. The magnitude of increase in the 3 groups of excellent, good, and fair was 3.18 ± 2.63, 2.53 ± 2.24 and 1.92 ± 1.80 mm, respectively. The rate of success was 81.8% with no statistically significant difference in the 3 groups. In a multivariate logistic regression, older age, local anaesthesia, and milder ptosis were predictors of success. A table of dose-response ratios was calculated that determined the amounts of levator muscle resection for 1 mm of marginal reflex distance 1 and levator function increase.

CONCLUSIONS

Levator resection has high success rate in patients with simple congenital ptosis. The function of levator muscle improved significantly following surgery, and the rate of improvement was higher in patients with better preoperative levator function.