Orbital Surgery Techniques

Orbital Anatomy & Approaches - Socket Blueprints

• Orbital Walls & Contents:

  • Roof: Frontal bone, lesser wing of sphenoid.
  • Floor: Maxilla, zygomatic, palatine. Weakest point: posteromedial floor (risk of blowout #).
  • Medial: Maxilla (frontal process), lacrimal, ethmoid (lamina papyracea - thin!), sphenoid (body).
  • Lateral: Zygomatic, greater wing of sphenoid. Strongest wall.
  • Apex: Optic canal (CN II, ophthalmic artery), superior orbital fissure (CN III, IV, V1, VI, sympathetic fibers, superior ophthalmic vein).
  • Contents: Globe, EOMs, nerves, vessels, fat, lacrimal gland.

• Surgical Spaces: Extraconal, intraconal, subperiosteal, sub-Tenon's.

• Common Surgical Approaches:

  • Anterior: Transconjunctival (inferior fornix, medial), transcutaneous (subciliary/Lynch/eyelid crease).
  • Lateral: Stallard-Wright orbitotomy.
  • Superior: Transcranial (neurosurgical).
  • Medial: Transcaruncular, endoscopic endonasal.

⭐ The lamina papyracea of the ethmoid bone is a paper-thin medial wall component, making it susceptible to fracture and infection spread from sinuses (orbital cellulitis).

Orbital Decompression Techniques - Pressure Drop Zone

*Goal: ↓ Orbital pressure, relieve optic nerve compression (ONC), ↓ proptosis. *Indications: - Thyroid Eye Disease (TED) with compressive optic neuropathy (CON) - Severe proptosis / exposure - Cosmesis *Bony Wall Removal (Creating Pressure Drop Zones): - Medial wall → Ethmoid sinus (max volume gain/wall) - Inferior wall (Floor) → Maxillary sinus - Lateral wall → Temporalis fossa / Greater wing of sphenoid - Balanced (2-3 walls) for graded effect. *Adjunct: Orbital fat decompression.

⭐ Medial wall decompression provides the most significant proptosis reduction per wall (approx. 4-6 mm) by using the ethmoid sinus as a pressure drop zone. *Complications: Diplopia (most common, esp. with floor/medial), sinusitis, hypoglobus, infraorbital anesthesia, CSF leak. 📌 Mnemonic for common walls: "My Floor Later" (Medial, Floor, Lateral).

Orbital Tumour Surgery Techniques - Lesion Eviction

• Goal: Complete tumour removal (excision) or debulking, preserving vision & function.
• Approach Selection: Based on tumour location, size, nature (benign/malignant), & surgeon expertise.

  • Anterior Orbitotomy:

    • For lesions in anterior 1/3 of orbit.
    • Transconjunctival or transcutaneous (e.g., eyelid crease, subciliary, Lynch incisions).

  • Lateral Orbitotomy (Kronlein):

    • Access to lateral, posterior, & apical lesions.
    • Involves temporary removal of lateral orbital wall.
    • Provides wide exposure.

  • Medial Orbitotomy:

    • For medial orbital wall lesions; often combined with ENT (transcaruncular, Lynch).

  • Superior Orbitotomy:

    • Transcranial (neurosurgical collaboration) for superior/apical lesions extending intracranially.

  • Inferior Orbitotomy:

    • Transconjunctival or subciliary approach for floor lesions.
• Techniques: Meticulous dissection, haemostasis, use of specialized orbital instruments.

⭐ High-Yield Fact: For intraconal tumours, lateral orbitotomy often provides the best access while minimizing risk to the optic nerve and extraocular muscles.

• Considerations: Biopsy (incisional/excisional), frozen section, reconstruction if needed (e.g., orbital implants).

Orbital Trauma & Reconstruction Techniques - Fix & Fill

• Fracture Types: Blowout (floor/medial wall), ZMC, NOE.
• Key Signs: Diplopia, enophthalmos (>2mm), hypoglobus, infraorbital anesthesia, restricted motility (FDT+).
• Surgical Timing: Early (≤2 wks) for entrapment; later for enophthalmos.
• "Fix": Anatomic reduction & rigid fixation (plates/screws).
• "Fill": Volume restoration: implants (autograft-bone; alloplast-Ti mesh, Medpor, PDS).
  • Approaches: Transconjunctival, subciliary, transcaruncular.

⭐ In pure blowout fractures, "white-eyed blowout fracture" (minimal external signs, significant motility restriction, often in children) requires urgent repair to prevent muscle ischemia.

High‑Yield Points - ⚡ Biggest Takeaways

• Transconjunctival approach: Scarless access for anterior/inferior orbital lesions.
• Lateral orbitotomy (Krönlein): For deep lateral/posterior lesions; risk of CN VII palsy.
• Orbital Decompression: For Graves' optic neuropathy/proptosis; involves bone/fat removal.
• Endoscopic surgery: Minimally invasive for medial/apical lesions, including optic nerve decompression.
• Biopsy: FNA (cytology), incisional/excisional (histology), guided by lesion characteristics.
• Intraoperative navigation: Increasingly used for complex cases to improve safety.
• Major risks: Vision loss, diplopia, CSF leak, retrobulbar hemorrhage.