A 5-year-old girl was referred for evaluation of blepharoptosis of the left eye present since birth (Figure). Her mother reported that, since infancy, the child’s left eye has twitched during feeding and mealtimes. The patient was born at term; had an unremarkable delivery; and had no history of developmental delay, trauma, or systemic illness. Her ocular history was significant only for bilateral mixed astigmatism (−0.25 + 0.75 × 145 OD and −0.25 + 1.00 × 005 OS). There was no family history of strabismus, amblyopia, or congenital ptosis. Her best-corrected visual acuity was 20/30 OD and 20/40 OS. Pupils were reactive to light bilaterally, and there was neither an afferent pupillary defect nor anisocoria. Extraocular motility was full. There was notable asymmetry in the following eyelid measurements: palpebral fissure height (10 mm OD; 5-6 mm OS) and margin reflex distance 1 (3.5 mm OD; 0.5-1.5 mm OS). In addition, elevation of the left upper eyelid was observed with lateral jaw thrust but not with anterior-posterior jaw movements or with mouth opening and closing. The levator function was 14 mm OU, and the margin crease distances were 5 mm OD and 6 mm OS. The remainder of the anterior and posterior segment slitlamp examination was unremarkable.