Digital analysis of unilateral ptosis repair: external levator advancement vs. Müller's muscle conjunctival resection

Evaluation of lid contour and marginal peak point changes to compare outcomes of external levator advancement and Miiller's muscle conjunctival resection surgery in unilateral ptosis.

We reviewed the charts of unilateral ptosis patients who underwent external levator advancement or Miiller's muscle conjunctival resection. Eyelid contour analysis was conducted on preoperative and 6-month postoperative digital images. This was performed with the multiple margin reflex distances technique, measuring the vertical distance from a line intersecting the center of the pupil to the eyelid margin at 10 positions at 2 mm intervals. The marginal peak point changes were analyzed digitally using the coordinates of the peak point according to the pupil center. Each position's mean distance was compared preoperatively, postoperatively, and with the fellow eyelid.

Sixteen patients underwent external levator advancement and 16 patients had Miiller's muscle conjunctival resection. The mean margin reflex distance was improved by both techniques (1.46 vs. 2.43 mm and 1.12 vs. 2.25 mm, p=0.008 and p=0.0001 respectively) and approached that of the fellow eyelid (2.43 vs. 2.88 and 2.25 vs. 2.58 mm, p=0.23 and p=0.19, respectively). However, statistically significant lid margin elevation was limited to between the N6 and T6 points in the external levator advancement group. Whereas, significant elevation was achieved along the whole lid margin in the Miiller's muscle conjunctival resection group. The marginal peak point was shifted slightly laterally in the external levator advancement group (p=0.11).

Both techniques provide effective lid elevation, however, the external levator advancement's effect lessens toward the canthi while Müller's muscle conjunctival resection provides more uniform elevation across the lid margin. The margin reflex distance alone is not sufficient to reflect contour changes.