The diagnosis of Horner syndrome is most often easy just based on the findings of anisocoria, with the small pupil not dilating well in the dark and decreased ipsilateral palpebral fissure.

Compensating for anesthesia-induced lagophthalmos and adjusting the palpebral fissure increased the predictability of eyelid height after surgery for pediatric congenital ptosis, a study found.

At the start of treatment, the average horizontal palpebral fissure length (HPF) was 50.9 percent of the reference value in the fifth percentile, while the last average measured HPF was 74.6 ...

On examination, the palpebral fissure measured 8 mm compared to 12 mm on the right. Visual acuity and ocular motility were unimpaired. There was loss of the upper lid sulcus and a soft mass ...