Peribulbar Block (PBB) for Cataract Surgery, Medicine and Techniques

Peribulbar Block (PBB)

A peribulbar block is a regional anesthetic technique that involves injecting a local anesthetic into the eye's extraconal compartment. It's commonly used for cataract surgery and intraocular lens implantation. 

Anesthesia Medicine Used in PBB

A combination of local anesthetics and adjuvants is used for better anesthesia.

Local Anesthetics

• Lidocaine (Lignocaine) 2% – 3 to 5 mL
• Bupivacaine 0.5% – 3 to 5 mL
• Ropivacaine 0.75% – Alternative to Bupivacaine

Adjuvants (Optional)

• Hyaluronidase (3-7.5 IU/mL) → Enhances diffusion
• Epinephrine/Adrenaline (1:200,000) → Prolongs action
• Dexmedetomidine/Clonidine → Prolongs analgesia

Dose and Volume Used

Total volume injected: 6 to 10 mL at two sites for better anesthesia.

Injection Sites (PBB Location)

Primary injection site: Inferotemporal region (about 4 mL medicine) and just space below supraorbital notch (about 1 mL to 2 mL ) . A secondary site is the medial canthus if needed.

Needle Type Used

Needle type: 23G or 25G blunt-tipped needle, length 25 mm to 40 mm.

Method of Administration

1. Position the patient supine with eyes in primary gaze.
2. Skin preparation with povidone-iodine.
3. Insert the needle at the inferotemporal site first and then just below space of supraorbital notch.
4. Aspirate before injecting.
5. Inject 6-10 mL of anesthetic slowly over 20-30 seconds.
6. Massage the injection site for 1-2 minutes. Don't press to the eye ball, only slowly massage through sterilized cotton patches to the upper and lower eyelid injection site for reducing swelling which create by anesthesia medicine.

Complications of PBB

Retrobulbar Hemorrhage (RBH)

Retrobulbar Hemorrhage (RBH) is a serious complication of peribulbar block (PBB) due to bleeding into the retrobulbar space. It can increase intraocular pressure (IOP) and cause vision loss if not managed quickly.

Causes of RBH in PBB

• Accidental arterial or venous puncture during needle insertion.
• High injection pressure causing vessel rupture.
• Injury to the short or long posterior ciliary arteries or ophthalmic artery.
• Use of anticoagulants (e.g., aspirin, warfarin) increasing bleeding risk.

Clinical Features of RBH

• 🔴 Sudden proptosis (forward displacement of the eye)
• 🔴 Severe pain and tight orbit
• 🔴 Rapid increase in intraocular pressure (IOP)
• 🔴 Subconjunctival hemorrhage (dark red or purple discoloration around the eye)
• 🔴 Loss of vision (due to optic nerve compression in severe cases)
• 🔴 Limited eye movement (ophthalmoplegia)

Grading of RB Hemorrhage

Grade	Clinical Features	Management
Mild	Minimal proptosis, no vision loss	Conservative (ice packs, monitor)
Moderate	Proptosis, subconjunctival hemorrhage, increased IOP	Medical treatment (IOP reduction)
Severe	Severe proptosis, optic nerve compression, vision loss	Urgent orbital decompression

🔹 Immediate Management

🔹 Medical Treatment

Reduce Intraocular Pressure (IOP) using:

• 💊 Acetazolamide 500 mg IV or PO (Carbonic anhydrase inhibitor)
• 💉 Mannitol 20% (1-2 g/kg IV) (Osmotic agent)
• 👁️ Topical beta-blockers (Timolol 0.5%)
• 🩺 Steroids (IV Dexamethasone 4-8 mg) to reduce inflammation.

🔹 Urgent Surgical Intervention

If vision loss or severe proptosis occurs → Perform Lateral Canthotomy & Cantholysis:

• 👨‍⚕️ Lateral canthotomy (surgical cut at the lateral canthus) relieves optic nerve pressure.
• ⏳ Must be done within 30-60 minutes to prevent permanent vision loss.

Prevention of RB Hemorrhage

• ✅ Use a blunt-tipped 25G needle to minimize vascular injury.
• ✅ Avoid multiple needle passes – Limit to a single smooth insertion.
• ✅ Aspirate before injecting to avoid intravascular injection.
• ✅ Inject slowly (~20-30 seconds) to prevent sudden pressure rise.
• ✅ Screen patients for bleeding disorders or anticoagulant use before the procedure.

Retrobulbar Hemorrhage (RBH) is a rare but serious complication of peribulbar block (PBB). Early recognition and prompt management are critical to preventing permanent vision loss. 

Other Ocular Complications

• Globe perforation (rare but serious)
• Subconjunctival hemorrhage
• Increased intraocular pressure

Neurological Complications

• Optic nerve damage (rare)
• Brainstem anesthesia

Systemic Complications

• Local anesthetic toxicity
• Allergic reaction
• Cardiovascular effects (bradycardia, hypotension)

Comparison with RB Block

Feature	Peribulbar Block (PBB)	Retrobulbar Block (RBB)
Injection Site	Outside the muscle cone	Inside the muscle cone
Needle Length	25-40 mm	35-40 mm
Complication Risk	Lower	Higher
Volume Injected	6-10 mL	3-5 mL

Advantages of Peribulbar Block

• Lower risk of globe perforation compared to RBB.
• More uniform akinesia.
• Less painful injection than RBB.

Disadvantages of PB Block

• Requires a larger volume of anesthetic.
• Slower onset of action (~5-10 min).

Clinical Pearls for Student

• Always aspirate before injecting.
• Use a blunt-tipped needle to reduce the risk of complications.
• Monitor for signs of systemic toxicity.

Conclusion

Peribulbar block (PBB) is a safer alternative to retrobulbar block in cataract surgery, providing effective analgesia and akinesia.