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Ptosis - Lid Liftoff Lowdown

  • Definition: Upper eyelid margin abnormally low.
    • Covers >2mm of superior cornea.
    • Or >1mm lower than contralateral lid.
  • Normal Values:
    • MRD1 (Margin-Reflex Distance 1): 4-4.5mm.
    • Palpebral Fissure Height (PFH): 9-12mm.
  • Key Elevators & Innervation:
    • Levator Palpebrae Superioris (LPS): CN III (Oculomotor); primary.
    • Müller’s Muscle: Sympathetic nerves; maintains 1-2mm tonic elevation.
    • Frontalis Muscle: CN VII (Facial); accessory, used in severe cases. Upper eyelid anatomy: levator and Muller's muscle

⭐ Myogenic ptosis is the most common acquired type, often due to levator dehiscence or dysgenesis (aponeurotic ptosis).

Ptosis - Droop Snoops

Upper eyelid droop with Margin Reflex Distance 1 (MRD1) < 2 mm or >2 mm asymmetry.

⭐ Myasthenia Gravis ptosis: characteristically worsens with sustained upgaze (fatigability) and improves with rest or ice pack test. Cogan's lid twitch may be present.

Ptosis - Eye Spy Sag

MRD and Palpebral Fissure Measurement in Ptosis

  • History: Onset (congenital/acquired), duration, variability (myasthenia), trauma, diplopia, family hx.
  • Key Signs: ↓Palpebral fissure, chin-up posture, frontalis overaction, abnormal lid crease, pupil/motility changes.
  • Measurements:
    • MRD1 (Margin-Reflex Distance 1): Corneal reflex to upper lid margin. Normal 4-4.5 mm.
      • Ptosis severity based on drop from normal: Mild (~2 mm), Mod (~3 mm), Severe (≥4 mm).
    • Levator Function (LF): Lid excursion (downgaze to upgaze, frontalis blocked).
      • Normal ≥15 mm; Good >8 mm; Fair 5-7 mm; Poor ≤4 mm.
  • Specific Tests:
    • Phenylephrine Test (10%): Positive if lid elevates 1-2 mm (Müller's muscle function).
    • Bell's Phenomenon: Assesses corneal protection during blink/sleep.
    • Cogan's Lid Twitch / Ice Pack / Fatigability Tests: For myasthenia gravis.
    • Marcus Gunn Jaw-winking: Synkinetic ptosis evaluation.

⭐ A positive phenylephrine test (upper lid elevation of ~2mm) is a strong indicator for a good outcome with Müllerectomy for ptosis correction.

Ptosis - Uplift & Unfurl

  • Definition: Abnormal drooping of the upper eyelid below its normal position.
  • Key Measurements:
    • Margin-Reflex Distance 1 (MRD1): Distance from corneal light reflex to upper lid margin. Normal: 4-4.5 mm.
    • Levator Function (LF): Total eyelid excursion from extreme downgaze to upgaze.
      • Normal: >12-15 mm
      • Good: >8 mm
      • Fair: 5-7 mm
      • Poor: ≤4 mm
    • Palpebral Fissure Height (PFH): Vertical distance between upper and lower lid margins in primary gaze. Normal: 9-12 mm.
  • Etiology:
    • Congenital: Simple, Blepharophimosis, Marcus Gunn Jaw-Winking.
    • Acquired: Aponeurotic (most common), Myogenic (e.g., Myasthenia Gravis), Neurogenic (e.g., CN III palsy, Horner's), Mechanical, Traumatic.

    ⭐ Horner's Syndrome triad: Miosis, Ptosis (mild, 1-2 mm), and Anhidrosis. Ptosis due to Müller's muscle paralysis.

Ptosis clinical measurement diagram

  • Surgical Approach Based on Levator Function:

  • 📌 Surgical Options Reminder "FLiM":

    • Frontalis Sling
    • Levator Resection
    • Mullerectomy (Fasanella-Servat procedure for mild ptosis with good LF, targets Müller's muscle)

High‑Yield Points - ⚡ Biggest Takeaways

  • Ptosis: Upper eyelid drooping; MRD1 < 2 mm is diagnostic (normal 4-4.5 mm).
  • Congenital ptosis: Most common, levator dysgenesis, poor levator function (LF), lid lag.
  • Aponeurotic ptosis: Most common acquired, good LF, high lid crease.
  • Myasthenia Gravis: Variable ptosis, fatigue-induced, Cogan's lid twitch, ice test positive.
  • Horner's syndrome: Mild ptosis (1-2 mm), miosis, anhydrosis.
  • Surgery: LF >8 mm → Levator resection; LF <4 mm → Frontalis sling operation.

Practice Questions: Ptosis

Test your understanding with these related questions

Which surgery is indicated for ptosis in Horner's syndrome?

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Flashcards: Ptosis

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_____ procedure is the treatment of choice for ptosis with poor levator elevation.

TAP TO REVEAL ANSWER

_____ procedure is the treatment of choice for ptosis with poor levator elevation.

Frontalis sling

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