Management of Ptosis

Classification

Clinical Evaluation — Key Measurements

• Margin-reflex distance (MRD): Distance from upper lid margin to corneal light reflex (normal 4–5 mm). Ptosis reduces this.
• Palpebral fissure height: Normal 7–10 mm (males), 8–12 mm (females). Ptosis graded as: mild (≤2 mm), moderate (3 mm), severe (≥4 mm).
• Levator function (lid excursion): Measured with brow immobilised; graded as:
  • Normal: ≥15 mm
  • Good: 12–14 mm
  • Fair: 5–11 mm
  • Poor: ≤4 mm
• Upper lid crease height: Normal ~10 mm (female), ~8 mm (male). Absence suggests poor levator function.
• Bell's phenomenon: Upward rotation of the globe on attempted lid closure — critically important before surgery to assess corneal exposure risk.

Pseudoptosis must be excluded — causes include ipsilateral hypotropia, contralateral lid retraction, orbital volume deficit (anophthalmic socket), brow ptosis, and dermatochalasis. — Kanski's Clinical Ophthalmology, p.87

Management Approach by Aetiology

1. Treat the Underlying Cause First

• Myasthenia gravis: Pyridostigmine, immunosuppression, thymectomy — ptosis often improves with systemic treatment.
• Horner syndrome: Investigate and treat the underlying cause; if mild, Müller resection is usually sufficient.
• 3rd nerve palsy: Observe; if palsy does not resolve, surgical correction may be considered once stable.
• Mechanical ptosis: Address the causative mass/scar.

Surgical Management

A. Conjunctiva–Müller Muscle Resection (Fasanella–Servat)

• Indication: Mild ptosis (1–2 mm) with good levator function (≥10 mm) — e.g. Horner syndrome, mild congenital ptosis.
• Mechanism: Excision of Müller muscle and overlying conjunctiva, with re-apposition of resected edges.
• Maximum elevation achievable: 2–3 mm.
• Approach: Transconjunctival (posterior).

B. Levator Advancement / Resection

• Indication: Ptosis of any cause with residual levator function ≥5 mm.
• Mechanism: The levator complex is shortened (resected) and advanced; the degree of resection is proportional to severity of ptosis and inversely proportional to levator function.
• Approach: Anterior (skin crease incision) or posterior (conjunctival).
  • Posterior approach offers better predictability of lid contour.
• Involutional ptosis specifically: Options include levator resection, advancement with reinsertion, or anterior levator repair.

The predictability of correcting lid height is equal whether anterior or posterior approach is used. — Kanski's Clinical Ophthalmology, p.93

C. Brow (Frontalis) Suspension

• Indication: Severe ptosis (>4 mm) with very poor levator function (<4 mm).
• Common causes requiring this: 3rd nerve palsy, blepharophimosis syndrome, congenital ptosis with absent levator function, unsatisfactory result from prior levator resection.
• Mechanism: The tarsal plate is suspended from the frontalis muscle using a sling material — the frontalis muscle then elevates the lid on upgaze/brow elevation.
• Sling materials:
  • Silicone rod — non-absorbable, adjustable, preferred in children and bilateral cases.
  • Autologous fascia lata — harvested from the thigh; more durable long-term but requires a second surgical site; used less commonly in recent years.

Special Situations

Congenital Ptosis

• Must check for amblyopia — the most important functional concern. Amblyogenic ptosis (covering the visual axis or causing significant astigmatism) requires early intervention.
• Assess with cycloplegic refraction and visual acuity.
• With good levator function: levator resection.
• With poor levator function: frontalis suspension (often with silicone rod in children).

Marcus Gunn Jaw-Winking Ptosis

• Mild cases (good levator function ≥5 mm, minimal winking): Unilateral levator advancement.
• Moderate cases: Unilateral levator disinsertion + ipsilateral frontalis suspension (lid elevation relies solely on frontalis, eliminating the winking component).
• Bilateral surgery: Bilateral levator disinsertion + bilateral frontalis suspension for symmetrical result.

Post-Cataract Surgery Ptosis

• Usually mild, secondary to multiple mechanisms (postoperative steroid drops, surgical trauma to aponeurosis).
• Generally improves spontaneously.
• Corrective lid surgery should not be undertaken for at least 1 year postoperatively.

Involutional (Aponeurotic) Ptosis

• Variable bilateral ptosis, high lid crease, good levator function.
• May worsen towards end of day — can mimic ocular myasthenia (key clinical tip).
• Treatment: Levator resection, advancement and reinsertion, or anterior levator repair.

Preoperative Considerations

• Bell's phenomenon: Patients with absent or poor Bell's phenomenon are at significant risk of corneal exposure/keratopathy following ptosis surgery — proceed with caution; may require conservative undercorrection or lid-taping instructions.
• Corneal sensation: Reduced sensation (e.g. 5th nerve disease) compounds exposure risk.
• Lubricants and ocular surface protection are essential postoperatively.

Summary Table: Surgery Selection