Wedge Excision and Pentagon Reconstruction of the Eyelid

Concept and Geometry

• The base is the eyelid margin
• The two parallel vertical sides are perpendicular to the lid margin and cover the full height of the tarsal plate
• The two oblique lower arms converge at a point toward the fornix (like an inverted "V"), completing the five sides
• All sides of the excision should be of equal length to ensure symmetric apposition
• The plane of section through the eyelid must be perpendicular to the lid margin - any oblique cut leads to misalignment and notching

Rules of Wedge/Pentagon Excision

1. The One-Third Rule (Size Limit for Direct Closure)

• Defects up to one-third of the lid margin length can be closed directly by simple apposition of the cut edges, because the eyelid has inherent elasticity
• In the elderly with lax skin, this extends to about one-quarter to one-third still applies, though some authors allow up to 40%
• Defects larger than one-third require additional tissue mobilization (lateral canthotomy/cantholysis, Tenzel semicircular flap, or more complex reconstruction)

2. Symmetry is Mandatory

• Both sides of the pentagon must be equal in length and depth
• Asymmetric sides cause one edge to ride higher than the other, creating a step deformity or notch at the lid margin

3. Perpendicularity of Cut

• The incision must be at 90° to the lid margin through the full thickness (skin, orbicularis, tarsus, conjunctiva)
• Any angling produces a beveled edge that cannot be perfectly apposed

4. Complete Full-Thickness Division

• Each layer must be cut cleanly: skin - orbicularis - tarsus - conjunctiva
• Partial cuts leave tethered tissue that puckers the margin on closure

5. Correction for Wound Contraction

• The amount of margin removed should be slightly less than the measured correction needed, because fibrosis and wound contraction provide an additional 0.5-1.0 mm of tightening

Layered Closure - Rules of Reconstruction

Layer 1: Tarsoconjunctival Layer (Posterior Lamella)

• Use 5-0 or 6-0 absorbable suture (e.g., Vicryl)
• Place a horizontal mattress suture through the anterior surface of the tarsus (partial thickness - must NOT penetrate conjunctiva, or the knot will abrade the cornea)
• The plane of the bites must be parallel to the lid margin
• The knot must be buried away from the margin and not exposed through the palpebral conjunctiva
• For very small resections (1-2 mm), this tarsal suture can be omitted and may actually hinder alignment

Layer 2: Lid Margin (the Most Critical Layer)

• Use 7-0 Vicryl or 6-0 silk sutures
• Place a vertical mattress (figure-of-eight) suture at the level of the Meibomian gland orifices - this is the landmark for perfect anatomical alignment
• A second vertical mattress suture at the level of the lash follicles (anterior lamella of the margin)
• Evert the lid margin slightly - slight eversion prevents late notching as the scar contracts
• Leave suture tails long and pull them away from the eye by incorporating them into the skin sutures or taping them to the skin - prevents corneal abrasion

Layer 3: Skin and Orbicularis (Anterior Lamella)

• Close with interrupted 6-0 or 7-0 absorbable or monofilament sutures
• Place skin sutures so they incorporate the long tags of the lid margin sutures to keep them off the cornea

Key Rules Summary Table

Clinical Indications for Pentagon Excision

• Eyelid tumors (e.g., basal cell carcinoma after Mohs excision)
• Ectropion repair - tarsoconjunctival pentagon excision to tighten a lax lid and correct misdirected lashes or keratinized conjunctiva (Kanski's Clinical Ophthalmology, 10th ed.)
• Entropion - localized marginal entropion, particularly after trauma
• Trichiasis - focal group of aberrant lashes
• Eyelid imbrication syndrome - pentagon resection combined with lateral canthal tightening
• Biopsy defects requiring full-thickness repair

What to Do When Pentagon Excision Alone is Insufficient

1. Lateral canthotomy and inferior cantholysis - releases the lateral canthal tendon to mobilize 3-5 mm of extra tissue medially
2. Tenzel semicircular rotation-advancement flap - skin and orbicularis pivoted on the lateral canthus; useful for defects up to ~50%
3. For >50% defects: Cheek rotation flap (lower lid), glabellar transposition flap, Cutler-Beard advancement flap, or switch flap (upper lid)