Ocular Anesthesia and Akinesia for Eye Surgery

Ocular anesthesia ensures pain-free surgery, while akinesia (absence of movement) prevents complications from involuntary eye movements. The choice depends on the procedure (e.g., cataract surgery, glaucoma surgery, retinal surgery) and patient factors.

1. Types of Ocular Anesthesia


A. Topical Anesthesia

  • Used for: Phacoemulsification, clear corneal incisions (minimally invasive procedures).

  • Agents:

    • Proparacaine 0.5% (rapid onset, short duration).

    • Lidocaine 2% gel (longer-lasting, better comfort).


  • Advantages:

    • No needle, quick recovery.

    • Patient can cooperate (e.g., fixate on microscope light).


  • Disadvantages:

    • No akinesia (eye can still move).

    • Risk of pain if surgery becomes complicated.


B. Sub-Tenon’s Anesthesia

  • Technique: Blunt cannula delivers anesthetic beneath Tenon’s capsule.

  • Agents: Lidocaine 2% + Bupivacaine 0.5% (with or without Hyaluronidase).



  • Advantages:

    • Good anesthesia & mild akinesia.

    • Lower risk of globe perforation vs. sharp needles.


  • Disadvantages:

    • Chemosis (swelling) may obscure surgical field.


C. Peribulbar Block

  • Injection Sites: Lower lid (inferotemporal) + upper lid (superonasal).

  • Agents: Lidocaine 2% + Bupivacaine 0.5% + Hyaluronidase.



  • Advantages:

    • Good anesthesia & akinesia.

    • Lower risk of brainstem anesthesia vs. retrobulbar.


  • Disadvantages:

    • Risk of retrobulbar hemorrhage, globe perforation.


D. Retrobulbar Block

  • Injection Site: Inside the muscle cone (deep orbital injection).

  • Agents: Same as peribulbar.



  • Advantages:

    • Excellent anesthesia & akinesia.


  • Disadvantages:

    • Higher risk of globe perforation, optic nerve injury, brainstem anesthesia.

E. General Anesthesia

  • Used for:

    • Children, uncooperative patients.

    • Long/complex surgeries (e.g., retinal detachment repair).


2. Achieving Akinesia (No Eye Movement)


  • Required for: Manual SICS, trabeculectomy, penetrating keratoplasty.

  • Best achieved with:

    • Peribulbar/Retrobulbar block (full akinesia).

    • Sub-Tenon’s (partial akinesia).


  • Assessing Akinesia:

    • Ask patient to look in all directions (no movement = successful block).

    • Bell’s phenomenon test (inability to roll eye upward = good akinesia).


3. Complications & Management

ComplicationCauseManagement
Retrobulbar HemorrhageTrauma to orbital vesselsStop surgery, apply pressure, check IOP.
Globe PerforationNeedle penetrates scleraImmediate ophthalmology consult, possible cryotherapy/scleral buckle.
Optic Nerve InjuryDirect trauma to optic nerveHigh-dose steroids, emergency imaging.
Brainstem AnesthesiaAnesthetic spreads to CNSSupportive care (airway management), usually resolves in hours.
Allergic ReactionHypersensitivity to anestheticStop drug, give antihistamines/steroids.



4. Special Considerations


  • Anticoagulated Patients:

    • Peribulbar/Sub-Tenon’s preferred (lower bleeding risk).

    • INR <3.0 acceptable for sharp needle blocks.

  • High Myopes: Higher risk of globe perforation → ultrasound-guided blocks or blunt cannula techniques.

  • Pediatric Patients: General anesthesia often preferred.

Key Takeaways

✔ Topical anesthesia → Quick, no akinesia (best for phacoemulsification).
✔ Peribulbar/Retrobulbar → Full anesthesia + akinesia (best for manual SICS).
✔ Sub-Tenon’s → Safer alternative with mild akinesia.
✔ Watch for complications (hemorrhage, perforation, brainstem anesthesia).

Comments

Post a Comment