In assessing the severity of congenital ptosis for surgical planning, the MOST important measurement is:

• A Palpebral fissure height in primary gaze
• B Presence or absence of Bell's phenomenon
• C Margin-to-reflex distance (MRD1) only
• D Levator palpebrae superioris (LPS) excursion (levator function) ✓

Explanation

Levator function (excursion of the upper eyelid from full downgaze to full upgaze with frontalis muscle blocked) is the most critical measurement guiding surgical approach. Good levator function (≥10 mm) → levator resection/advancement; fair function (5–9 mm) → maximum levator resection; poor function (<4 mm) → frontalis suspension (brow suspension) using autogenous fascia lata or silicone sling. Palpebral fissure and MRD1 quantify the degree of ptosis but do not determine technique. Bell's phenomenon is important for corneal safety considerations but does not drive the surgical plan.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.