A peribulbar block is a regional anesthesia technique used to numb the eye and freeze its movement before surgery. An anesthesiologist or ophthalmologist injects local anesthetic solution into the space surrounding the eyeball but outside the cone of muscles that control eye movement. The injection numbs the sensory and motor nerves in the orbit, producing both pain relief and a temporary inability to move the eye, which gives the surgeon a still, cooperative surgical field. It is one of the most widely used forms of eye anesthesia worldwide, particularly for cataract surgery, and has a long track record of safety.
How the Block Works
Your eye sits inside a bony socket filled with fat, connective tissue, and muscles that move the globe in different directions. Behind the eye, these muscles form a cone-shaped space. In an older technique called the retrobulbar block, the needle goes inside that muscle cone to deliver anesthetic directly behind the globe. A peribulbar block keeps the needle outside the cone, depositing anesthetic in the fatty tissue surrounding it. The drug then gradually diffuses inward through the tissues to reach the nerves.
Because the injection stays outside the muscle cone, the needle does not need to travel as deep, which reduces the chance of accidentally hitting the optic nerve or a blood vessel behind the eye. The trade-off is that peribulbar blocks sometimes need a slightly larger volume of anesthetic and can take a few extra minutes to reach full effect compared with retrobulbar injections. Typically the injection is placed in the lower outer part of the orbit, though some surgeons use additional injection sites or vary the approach depending on the patient’s anatomy.
Peribulbar Versus Retrobulbar
For decades the retrobulbar block was the standard for eye surgery. It works fast and produces reliable numbness and stillness, but the deeper needle placement carries a small risk of serious complications like optic nerve damage or bleeding behind the eye. A large prospective study of over 16,000 consecutive peribulbar blocks found the technique to be as effective as retrobulbar anesthesia while appearing to produce fewer sight-threatening and life-threatening complications, even when surgeons used slightly different peribulbar approaches from one another.1Journal of Cataract & Refractive Surgery. Efficacy and complication rate of 16,224 consecutive peribulbar blocks: A prospective multicenter study That safety advantage drove much of the shift toward peribulbar blocks starting in the 1980s and 1990s, and today many ophthalmic anesthetists consider them the default needle-based block for routine cases.2PubMed. Needle-based blocks for the 21st century ophthalmology
How It Compares to Topical Anesthesia
Not every eye surgery needs an injection at all. Topical anesthesia, using numbing drops placed on the surface of the eye, has become common for shorter cataract procedures done through small incisions. The comparison between topical and peribulbar approaches is not straightforward, and the trial evidence splits depending on what you measure.
One randomized trial found that when cataract surgery was done through a scleral pocket incision, patients in the topical group reported significantly more pain than those who received a peribulbar block, and unwanted eye movements happened more often with topical alone.3PubMed. Pain in scleral pocket incision cataract surgery using topical and peribulbar anesthesia Another trial using a clear corneal approach found comparable pain scores between the two methods, though eye movement control was actually better with topical anesthesia in that particular surgical technique.4PubMed. Topical versus peribulbar anesthesia in clear corneal cataract surgery A third randomized study found that both patients and surgeons were more satisfied with peribulbar anesthesia overall, with the difference in pain mitigation reaching statistical significance.5PubMed Central. Comparison of clinical outcomes, patient, and surgeon satisfaction following topical versus peribulbar anesthesia for phacoemulsification and intraocular lens implantation: a randomized, controlled trial
In practice, the choice often comes down to the type of surgery and the surgeon’s comfort. Topical anesthesia is appealing because it avoids needles entirely, but it does not freeze eye movement. For operations that require a perfectly still globe, or for patients who are anxious and likely to move, a peribulbar block provides a more controlled environment.
How It Compares to a Sub-Tenon Block
A sub-Tenon block is another injection alternative that has gained popularity. Instead of going through the skin or conjunctiva with a needle, the surgeon makes a tiny opening in the membrane covering the white of the eye and slides a blunt cannula underneath it to deliver anesthetic. One study comparing the two techniques in small-incision cataract surgery found that the sub-Tenon block hurt less going in and had a faster onset of action, but the peribulbar block produced more complete eye stillness, with about 83% of patients achieving full akinesia compared to roughly 74% achieving only partial akinesia in the sub-Tenon group.6PubMed Central. A comparison of sub-tenon block with peribulbar block in small-incision cataract surgery Another trial found the two techniques comparable in both pain control and adequacy of akinesia during surgery, though chemosis (swelling of the conjunctival membrane) and subconjunctival hemorrhage were more common with the sub-Tenon approach.7PubMed Central. Comparison of Peribulbar with Posterior Sub-Tenon’s Anesthesia in Cataract Surgery Among Nigerians
Each method has its niche. When absolute eye stillness matters, such as for delicate vitreoretinal work, the peribulbar block’s stronger akinesia is an advantage. When comfort during the injection itself is a priority and the surgery is relatively brief, the sub-Tenon approach may win out.
Which Surgeries Use a Peribulbar Block
Cataract surgery is the most common reason you would receive a peribulbar block, but it is not the only one. Vitreoretinal surgeries, which involve work on the retina or the gel inside the eye, can also be done under peribulbar anesthesia. In one early study of vitreoretinal procedures, peribulbar anesthesia alone provided adequate numbness and stillness in about 79% of vitrectomy patients, and with supplemental medication the completion rate reached 97%.8Ophthalmic Surgery, Lasers and Imaging Retina. Peribulbar Anesthesia for Primary Vitreoretinal Surgery The block was less reliable when scleral buckling, a procedure where a silicone band is placed around the outside of the eye, was involved. That study’s authors recommended peribulbar anesthesia primarily for vitrectomy patients, reserving it as a backup for scleral buckling when general anesthesia is contraindicated.
Other ophthalmic procedures, including glaucoma surgeries, corneal transplants, and some oculoplastic operations, can also be performed under peribulbar block depending on the surgeon’s preference and the expected length of the procedure. For longer surgeries, adjuvant medications that extend the block’s duration become especially useful.
Drugs and Additives Used in the Block
The typical peribulbar block uses a mixture of local anesthetics. Common choices include lidocaine, which acts quickly but wears off relatively fast, and bupivacaine or levobupivacaine, which take slightly longer to kick in but last much longer. Blending the two gives both rapid onset and sustained numbness. The concentration matters too: a study comparing 2% and 3% chloroprocaine solutions found that the stronger concentration produced surgical anesthesia roughly two minutes faster on average, though recovery also took about 15 minutes longer.9PubMed. Randomized double-blind study of the clinical duration and efficacy of Nesacaine-MPF 2% and 3% in peribulbar anesthesia
An enzyme called hyaluronidase is one of the most commonly added extras. It breaks down hyaluronic acid in the tissue surrounding the eye, which helps the anesthetic spread more evenly and reach the nerves faster.10PubMed Central. Role of hyaluronidase as an adjuvant in local anesthesia for cataract surgery A randomized trial confirmed that adding hyaluronidase in either of two concentrations improved the quality of the block at five minutes, and the higher concentration also sped up the onset of numbness and stillness.11PubMed. Hyaluronidase and peribulbar block
Researchers have tested other additives to push the block’s performance further. A meta-analysis found that dexmedetomidine, a sedative-analgesic drug, extended both the motor and sensory block by roughly an hour or more, reduced eye pressure, cut the need for supplemental injections by more than half, and increased surgeon satisfaction when added to the local anesthetic.12PubMed. Efficacy of Dexmedetomidine as an Adjuvant to Local Anesthetics in Peribulbar Block: A Meta-analysis With Trial-Sequential Analysis Dexamethasone, a steroid, showed similarly prolonged anesthesia and akinesia in a head-to-head comparison with dexmedetomidine, though the latter had a slightly faster onset.13PubMed Central. Dexamethasone Compared to Dexmedetomidine as an Adjuvant to Local Anesthetic Mixture in Peribulbar Block for Vitreoretinal Surgery. A Prospective Randomized Study Ketamine added to the block has also been shown to hasten onset and prolong duration, which is desirable in longer vitreoretinal cases.14PubMed. Ketamine versus midazolam as an adjuvant to peribulbar block in patients undergoing vitreoretinal surgery: A randomized controlled trial
Common Minor Complications
The most frequent side effect is mild bruising. A prospective study of nearly 1,400 patients found that about 4% developed visible lid hemorrhages after their injection, and in most of those cases the bruising was just a small spot.15British Journal of Anaesthesia. Haemorrhage and risk factors associated with retrobulbar/peribulbar block: a prospective study in 1383 patients No patient in that study experienced a serious retrobulbar hemorrhage with elevated eye pressure. Chemosis, a puffy swelling of the membrane over the white of the eye, is also common and generally resolves on its own.
Subconjunctival hemorrhage, a small red patch on the white of the eye from a broken blood vessel, happens occasionally and looks alarming but is harmless. In rare instances, the bruising can be more dramatic. One case report described a bilateral orbital hemorrhage after a peribulbar block in a 78-year-old man, where bleeding spread from the injected side to the opposite eye, though neuro-ophthalmological evaluation showed normal retinal blood flow.16PubMed Central. Peribulbar anesthesia causing bilateral orbital hemorrhage Another case involved a patient with a rare clotting disorder who developed a hematoma under the bone lining of the orbit after a peribulbar injection, leading to temporary optic nerve compression.17International Medical Case Reports Journal. Subperiosteal hematoma from peribulbar block during cataract surgery leading to optic nerve compression in a patient with parahemophilia These severe bleeding events are exceedingly uncommon in people with normal clotting.
Rare but Serious Risks
The risk that gets the most attention in medical literature is globe perforation, where the needle accidentally punctures the eyeball. People with high myopia (severe nearsightedness) are at increased risk because their eyes are elongated, which changes the geometry of the orbit and makes the globe harder to avoid. One study confirmed myopia as a risk factor for perforation during regional eye anesthesia.18PubMed Central. Percaruncular single injection peribulbar anaesthesia in patients with axial myopia for phacoemulsification However, research on the actual dimensions of myopic eyes suggests that perforation risk with peribulbar injections can remain low when a careful approach through the inner corner of the eye is used.19British Journal of Anaesthesia. Altered globe dimensions of axial myopia as risk factors for penetrating ocular injury during peribulbar anaesthesia
An even rarer event is brainstem anesthesia, where the local anesthetic tracks backward along nerve sheaths and reaches the brain. A case report described a patient who, within minutes of a peribulbar injection, developed confusion, low blood pressure, dilation of the opposite pupil, and then lost consciousness and stopped breathing.20PubMed Central. Complication of Peribulbar Block: Brainstem Anaesthesia The patient recovered fully with supportive care, but the report underscores why peribulbar blocks should be performed with full monitoring equipment and resuscitation drugs at hand.
Another reflex-based complication is the oculocardiac reflex, where pressure or traction on the eye or surrounding tissues triggers a sudden drop in heart rate. One case described a 64-year-old woman whose heart rate dropped sharply during the injection itself. The anesthesiologist stopped the injection, and her heart rate returned to normal within about 30 seconds without needing medication.21PubMed Central. Oculocardiac Reflex During Peribulbar Block: A Case Emphasizing the Role of Monitoring in Early Recognition This reflex is well-known in ophthalmic surgery and is one of the reasons continuous heart-rate monitoring is standard during the procedure.
Blood Thinners and Special Situations
Many people who need cataract surgery are on anticoagulant medications like warfarin for heart conditions or blood clots. Stopping these drugs for surgery carries its own risks, so the question of whether a peribulbar block is safe without discontinuing them matters. A study of 750 patients on oral anticoagulants found no significant increase in sight-threatening hemorrhagic complications compared to patients not on blood thinners. Minor bruising rates were statistically similar between the two groups.22PubMed Central. Peribulbar anesthesia in 750 patients treated with oral anticoagulants In cardiac patients specifically on warfarin, a comparison with the sub-Tenon technique found that the peribulbar approach actually produced less hemorrhage (about 8% versus 30%), and no patient in either group experienced a sight-threatening bleed.23Egyptian Journal of Anaesthesia. Peribulbar versus sub-Tenon block in cardiac patients undergoing cataract surgery during warfarin therapy
This evidence is reassuring, but each case is different. Someone on multiple blood-thinning medications or with a known bleeding disorder faces higher risk, as the case of the patient with parahemophilia described earlier illustrates. The decision about continuing or pausing anticoagulants is made jointly by the ophthalmologist and the prescribing physician, weighing the bleeding risk of the block against the clotting risk of stopping the drug.
Sedation During the Block
Even though a peribulbar block numbs the eye effectively, many patients are understandably anxious about receiving a needle injection near their eye. Light sedation before the block can help. One study evaluated a low dose of propofol given just before the peribulbar injection and found it abolished the patient’s memory of the injection in about 88% of cases, without causing major side effects.24Eye. Efficacy and safety of sedation with propofol in peribulbar anaesthesia This is not general anesthesia; the patient remains breathing on their own and can still follow instructions during surgery. The sedation essentially covers the brief uncomfortable part, the injection itself, while the block handles everything during the operation.
Ultrasound-Guided Blocks
Traditionally, peribulbar injections are performed by feel, with the anesthesiologist relying on anatomical landmarks and the sensation of the needle passing through tissue. Ultrasound guidance is a newer refinement. During an ultrasound-guided block, a probe is placed over the closed eyelid and the eye’s internal structures are visualized on a screen. The anesthesiologist can watch the needle’s path in real time and see the anesthetic solution spreading through the orbital tissue as it is injected.25Regional Anesthesia & Pain Medicine. Real-Time Evaluation of Diffusion of the Local Anesthetic Solution During Peribulbar Block Using Ultrasound Imaging and Clinical Correlates of Diffusion
In practice, the procedure involves applying a thick layer of ultrasound gel to the closed eyelids and scanning the globe in multiple planes before inserting the needle.26PubMed. Ultrasound-guided versus conventional peribulbar anaesthesia in cataract surgery: A randomised controlled study The theoretical appeal is clear: being able to see where the needle is going and confirm that anesthetic is reaching the right spaces should improve both safety and effectiveness, especially in patients with unusual anatomy like highly myopic eyes. Adoption has been slow in everyday ophthalmic practice, partly because the landmark-based technique already works well in experienced hands and ultrasound adds setup time. But as imaging equipment becomes more portable and its use becomes routine training, this is likely to grow.
Use in Children
Peribulbar blocks are primarily associated with adult eye surgery, but they have a role in pediatric cases too, typically combined with general anesthesia rather than replacing it. In one study of pediatric cataract surgery in Nepal, general anesthesia with ketamine was combined with a peribulbar block of lidocaine in all patients. The combination was well tolerated, produced significant visual improvement, and caused no anesthesia-related complications.27PubMed. Pediatric cataract surgery in Nepal
Another study compared children who received a peribulbar block as an add-on to general anesthesia with those who received general anesthesia alone. The children in the block group needed less pain medication during and after surgery, had lower pain scores at every time point measured, experienced fewer episodes of the oculocardiac reflex, and had a dramatically lower rate of postoperative nausea and vomiting (about 20% versus 76%).28PubMed. Safety and efficacy of peribulbar block as adjunct to general anaesthesia for paediatric ophthalmic surgery No block-related complications occurred. The takeaway is that even in children who are asleep for surgery, a peribulbar block adds meaningful pain control and makes recovery smoother.