The Peribulbar Block: A Comprehensive Clinical and Historical Review

Introduction: The Peribulbar Block in Modern Ophthalmic Practice

The peribulbar block stands as a cornerstone technique in the practice of regional ophthalmic anesthesia. For decades, it has been a workhorse for surgeons and anesthesiologists, providing the necessary pain control (anesthesia) and eye muscle paralysis (akinesia) for a vast array of delicate eye surgeries.¹ Its widespread adoption is a direct result of its favorable balance between high efficacy and an improved safety profile compared to its predecessor, the retrobulbar block.³ The history of the peribulbar block is, in essence, a story of medical innovation driven by the fundamental goal of enhancing patient safety. Its development was a direct and deliberate response to the known and significant risks associated with placing a needle into the dense, critical space directly behind the eyeball.³

This technique is routinely employed for some of the most common and complex procedures in ophthalmology, including cataract extraction, glaucoma surgery, corneal transplantation, and vitreoretinal repairs.² However, the field of ophthalmic anesthesia is not static. The peribulbar block, once the safer alternative, now finds itself in a dynamic landscape where it is compared with even less invasive methods, such as the blunt-cannula sub-Tenon's block and, for certain procedures, needle-free topical anesthesia.⁶ This ongoing evolution underscores a continuous quest within the medical community to refine techniques, minimize risk, and optimize the patient experience. This report provides an exhaustive review of the peribulbar block, tracing its history, deconstructing its anatomical and physiological basis, detailing its clinical application, and offering a clear-eyed assessment of its risks and benefits in the context of modern ophthalmic practice.

Foundational Concepts: Anatomy and Terminology

A precise understanding of the peribulbar block begins with the language used to describe the intricate anatomy of the orbit—the bony cavity that houses the eye. The terminology is not merely academic; it defines the procedure's goals, techniques, and inherent safety considerations.

The Language of the Orbit: Deconstructing "Peribulbar"

The term "peribulbar" is a hybrid of Greek and Latin roots that provides a literal and descriptive definition of the anatomical region of interest. The prefix, peri-, originates from the Greek word περί (peri), meaning "around" or "surrounding".⁹ The root word,

bulbar, is derived from the Latin bulbus, which refers to a bulb-like structure—in this context, the eyeball or ocular globe itself.¹⁰ Therefore, the term "peribulbar" translates directly to "around the eyeball".¹¹ As an adjective, it describes any anatomical location, pathological process, or medical procedure that occurs in the space immediately surrounding the globe but within the confines of the bony orbit.

Mapping the Territory: The Extraconal and Intraconal Spaces

The orbital cavity is not a homogenous space. It is critically divided into two main compartments by a cone-shaped structure formed by the four rectus muscles (superior, inferior, medial, and lateral) that control eye movement. These muscles originate at the apex of the orbit and attach to the eyeball, forming a "muscle cone" that envelops the most critical structures.⁶

• Intraconal Space: This is the compartment located inside the muscle cone, posterior to the globe. It is a space densely packed with vital neurovascular structures, including the optic nerve (cranial nerve II), the oculomotor nerve (III), the abducens nerve (VI), the ciliary ganglion (a nerve bundle controlling pupil size and focus), and major arteries and veins supplying the eye. This space is the intended target for a retrobulbar block.¹¹
• Extraconal Space: This compartment is located outside the muscle cone but still within the bony orbit. It is primarily filled with adipose (fat) tissue, which acts as a cushion for the eye. The extraconal space is the intended deposition site for the anesthetic solution in a peribulbar block.⁶ The fundamental principle of the peribulbar technique is to place the anesthetic in this relatively safer, less crowded space and allow it to diffuse inward to reach the nerves within the cone.⁶

While the clinical definitions seem clear—peribulbar is extraconal, and retrobulbar is intraconal—the anatomical reality is more nuanced. The term "retrobulbar" simply means "behind the eyeball".¹¹ Any needle-based block that delivers anesthetic behind the eye must, by definition, first pass through the peribulbar space. Unless the needle punctures the globe itself, it is always technically "around the eye".¹¹ This reveals that the truly critical distinction for safety and efficacy is not the name of the block but the final anatomical destination of the needle tip: intraconal versus extraconal. This understanding reframes the safety debate. A blanket statement that a peribulbar block is "safer" is an oversimplification. It is the

extraconal placement of the needle tip that is theoretically safer because it intentionally avoids the dense cluster of nerves and vessels within the muscle cone. This also explains why serious complications can still occur with peribulbar blocks and why some studies report similar complication profiles; the needle path itself shares common territory and risks, and an errant needle intended for the extraconal space can still enter the intraconal space or damage nearby structures.¹¹

Critical Structures within the Peribulbar Field

The ultimate goal of a peribulbar block is to achieve two distinct physiological effects: anesthesia and akinesia.

• Anesthesia (Pain Blockade): Sensory innervation to the cornea, uvea, and conjunctiva is primarily provided by the ophthalmic division of the trigeminal nerve (cranial nerve V1). The block aims to bathe these nerve fibers in anesthetic to prevent the patient from feeling pain during surgery.¹⁹
• Akinesia (Movement Blockade): Movement of the eye is controlled by the extraocular muscles, which are innervated by three motor nerves: the oculomotor nerve (III), the trochlear nerve (IV), and the abducens nerve (VI). Paralysis of these muscles is crucial to prevent eye movement during microscopic surgery, ensuring a stable surgical field. The anesthetic diffuses from the extraconal space to block these motor nerves.¹⁹ A unique advantage of the peribulbar block is its effect on the facial nerve (VII), which innervates the orbicularis oculi muscle responsible for eyelid closure (blinking or squeezing). The large volume and diffuse spread of a peribulbar block often anesthetize the branches of this nerve supplying the eyelid, preventing the patient from squeezing their eye shut during surgery—a protective reflex that is not reliably blocked by the more targeted retrobulbar technique.¹⁸

The Evolution of Ocular Anesthesia: A Historical Perspective

The peribulbar block did not emerge in a vacuum. It represents a key milestone in a long and ongoing history of medical innovation aimed at making eye surgery safer and more tolerable for patients. Its development can only be fully understood in the context of the techniques that preceded it and the surgical advancements that ran in parallel.

The Genesis of Regional Anesthesia in Ophthalmology

For centuries, eye surgery was a brutal affair performed with minimal or no anesthesia. The modern era of ophthalmic anesthesia began in the landmark year of 1884. At a medical conference, the work of a young Austrian ophthalmologist, Dr. Carl Koller, was presented, demonstrating that a solution of cocaine dropped onto the surface of the eye produced profound local anesthesia.⁶ Koller's discovery, which built upon earlier observations of cocaine's numbing properties by chemists like Albert Niemann, was revolutionary.²⁰ It allowed surgeons to perform delicate procedures on an awake but pain-free patient, a dramatic improvement over the high-risk alternative of general anesthesia with chloroform or ether.²³ This breakthrough was made possible by the concurrent development of the hypodermic syringe and hollow needle, which allowed for the injection of anesthetic agents directly into tissues.²¹

The Predecessor: The Rise and Risks of the Retrobulbar Block

In the very same year that Koller introduced topical anesthesia, another ophthalmologist, Dr. Herman Knapp, described the first injectable technique for deeper orbital anesthesia: the retrobulbar block.¹⁴ Using cocaine and a hypodermic needle, Knapp injected the anesthetic into the space directly behind the eyeball. This technique was later refined and popularized by Dr. W.S. Atkinson in 1936 and, for the better part of a century, was considered the "gold standard" for intraocular surgery.¹⁴ It provided rapid and profound akinesia, creating a perfectly still and numb eye, which was ideal for the complex, large-incision surgeries of the era.¹⁴

However, the retrobulbar block carried significant and well-documented risks. The procedure involved the "blind" placement of a long, sharp needle into the anatomically crowded intraconal space. This placed the needle tip in immediate proximity to the optic nerve, the ophthalmic artery, and other critical structures. Consequently, the technique was associated with a risk of devastating, sight- and life-threatening complications, including perforation of the eyeball, hemorrhage behind the eye (retrobulbar hemorrhage), direct trauma to the optic nerve, and inadvertent injection into the cerebrospinal fluid surrounding the optic nerve, which could lead to seizures and respiratory arrest (brainstem anesthesia).¹⁴

A Paradigm Shift: The Introduction of the Peribulbar Block (1986)

The search for a safer alternative to the retrobulbar block culminated in 1986. In a pivotal publication, Drs. D.B. Davis and M.R. Mandel described their technique of "posterior peribulbar anesthesia".³ Their innovation was conceptually simple but profound: instead of aiming for the high-risk intraconal space, they proposed injecting a larger volume of local anesthetic into the relatively safer, fat-filled extraconal space.³ The underlying theory was that the anesthetic would then diffuse from this safer peripheral location inward to the muscle cone, achieving the desired anesthetic and akinetic effects without the need to place a needle directly among the orbit's most vulnerable structures.³ This technique was designed explicitly to minimize the most feared complications of the retrobulbar block and represented a major paradigm shift toward prioritizing safety in regional ophthalmic anesthesia.³

This evolution in anesthetic practice was not independent of surgical progress. It was, in fact, intrinsically linked to and propelled by the revolution in cataract surgery. The older, large-incision techniques like intracapsular cataract extraction were lengthy and demanded the absolute immobility that a potent retrobulbar block provided.²⁹ However, the invention of phacoemulsification by Dr. Charles Kelman in 1967 transformed cataract removal into a much faster, small-incision, and less traumatic procedure.²⁹ This new surgical reality reduced the absolute requirement for prolonged and profound akinesia. This, in turn, created a clinical environment where less invasive anesthetic techniques were not only possible but preferable. The peribulbar block, introduced in 1986, was perfectly timed to meet this new demand and gained rapid and widespread acceptance. The trend continued, and by the 1990s, even less invasive methods like the sub-Tenon's block and topical anesthesia became standard options for routine cataract surgery, demonstrating a clear causal link where anesthetic innovation follows and adapts to the needs of surgical innovation.⁶

The Peribulbar Block in Practice: Mechanism, Agents, and Technique

The clinical application of the peribulbar block is a precise procedure grounded in an understanding of orbital anatomy, pharmacology, and patient safety protocols. Its effectiveness relies on a specific physiological mechanism and a carefully selected combination of anesthetic agents.

The Physiological Mechanism: Achieving Anesthesia and Akinesia

Unlike the retrobulbar block, which delivers a small volume of anesthetic directly to its target, the peribulbar block works through volume-driven diffusion.⁶ A relatively large volume of local anesthetic, typically between 6 and 10 mL, is injected into the extraconal space.⁶ This injected volume increases the pressure within the extraconal compartment, forcing the anesthetic solution to spread throughout the orbital fat. The muscle cone is not a completely sealed structure; it is an incomplete fibromuscular cone with gaps that allow for this diffusion.⁶ The anesthetic percolates through these gaps into the intraconal space, where it finally reaches its targets: the sensory ciliary nerves for anesthesia and the motor cranial nerves (III, VI, and sometimes IV) for akinesia.¹⁹

This indirect mechanism of action accounts for the characteristic properties of the peribulbar block. Because the anesthetic must travel from the periphery to the central target, the onset of action is slower than a retrobulbar block, typically taking 10 to 15 minutes to become fully effective.⁶ Furthermore, because the diffusion may not be perfectly uniform, the resulting akinesia can sometimes be incomplete, occasionally requiring a supplemental injection to paralyze a muscle that was missed by the initial block.¹⁵

The Anesthesiologist's Armamentarium: Anesthetic Agents and Adjuvants

The solution injected for a peribulbar block is rarely a single drug. It is typically a "cocktail" of several agents, each chosen for a specific purpose to create an optimal block with rapid onset, sufficient duration, and good quality.³¹

• Local Anesthetics: The foundation of the block is a combination of two types of local anesthetic. A short-acting agent, most commonly Lidocaine 2%, is used for its rapid onset of action, typically within minutes. This is combined with a long-acting agent, such as Bupivacaine 0.5% or 0.75%, which has a slower onset but provides anesthesia for several hours, ensuring the patient remains comfortable throughout the surgery and well into the postoperative period.¹⁹
• Spreading Agent: Hyaluronidase is a critical adjuvant in modern peribulbar anesthesia. It is an enzyme that temporarily breaks down hyaluronic acid, a component of the connective tissue matrix. This action reduces tissue viscosity, allowing the local anesthetic solution to spread more easily and widely through the orbital fat.¹⁹ The result is a faster onset, a more uniform and complete block, and the ability to use a slightly lower total volume of anesthetic.²³
• Vasoconstrictor: Epinephrine (adrenaline) is sometimes added to the anesthetic mixture in a dilute concentration (e.g., 1:200,000).³⁵ It causes local vasoconstriction (narrowing of blood vessels), which serves two purposes: it slows the rate at which the anesthetic is absorbed into the bloodstream, thereby prolonging its local effect, and it reduces the risk of systemic toxicity.¹⁹ However, its use is debated and often avoided, as it carries a theoretical risk of causing vasospasm in the delicate arteries supplying the optic nerve and retina, which could lead to ischemia.²⁶

The following table summarizes the key agents used in a typical peribulbar block.

A Procedural Guide to Peribulbar Block Techniques

The administration of a peribulbar block is a skilled procedure that requires a thorough knowledge of orbital anatomy and adherence to strict safety protocols. The process begins with pre-procedure checks, including confirming the correct patient and surgical eye, assessing for risk factors, and ensuring that full monitoring and resuscitation equipment are immediately available.¹⁹ The patient is typically positioned supine, and intravenous access is established for the administration of sedation if needed.⁵

The Standard Inferotemporal Injection

The most common technique involves one or two injections. The primary injection is typically given at the inferotemporal quadrant of the orbit.¹

1. The clinician palpates the inferior orbital rim. The injection site is identified at the junction of the lateral one-third and medial two-thirds of this bony margin.¹⁸
2. A relatively short needle (e.g., 25-gauge, 16-25 mm long) is used to minimize the risk of damaging posterior structures.²⁷
3. With the patient looking straight ahead in a neutral gaze, the needle is inserted through the skin or conjunctiva at the chosen site.
4. The needle is advanced posteriorly, keeping it parallel to the floor of the orbit and angled slightly away from the globe itself, until its tip is judged to have passed the equator of the eyeball.⁵
5. After carefully aspirating to ensure the needle is not in a blood vessel, a volume of 4-6 mL of anesthetic solution is slowly injected into the extraconal space.¹⁸

The Medial Canthal Injection and Supplemental Blocks

Often, a single inferotemporal injection is insufficient to produce complete akinesia, particularly of the medial rectus and superior oblique muscles.¹⁸ Therefore, a second injection is frequently performed.

1. The medial canthal block is a common and effective supplemental injection.¹⁸ A shorter needle is inserted just medial to the caruncle (the small, pink nodule in the inner corner of the eye) and advanced posteriorly for about 10-15 mm.¹⁸
2. After aspiration, an additional 2-4 mL of anesthetic is injected to complete the block.¹⁸
3. In cases where eyelid squeezing (blepharospasm) is a concern, a separate Van Lindt facial nerve block may be performed by injecting anesthetic near the lateral orbital rim to paralyze the orbicularis oculi muscle.¹⁸

After the injections, gentle pressure may be applied to the closed eye for several minutes to facilitate the spread of the anesthetic and to lower the intraocular pressure, which transiently rises due to the injected volume.²⁷ The effectiveness of the block is then assessed by checking for the absence of eye movement in all directions of gaze.¹⁹

Clinical Utility and Comparative Efficacy

The peribulbar block is a versatile tool used across a wide spectrum of ophthalmic surgeries. Its selection over other anesthetic techniques is based on a careful weighing of the surgical requirements, patient-specific factors, and the comparative risks and benefits of the available options.

Primary Indications for Peribulbar Anesthesia

A peribulbar block is indicated for procedures that require a significant degree of both anesthesia and akinesia for surgical success and patient safety. It is a workhorse technique for many common and complex intraocular surgeries, including:

• Cataract Surgery: While many routine cataract surgeries are now performed under topical or sub-Tenon's anesthesia, the peribulbar block remains essential for more complex or prolonged cases, such as those involving a very dense lens, a subluxated lens, or in patients who are highly anxious or unable to cooperate.²
• Vitreoretinal Surgery: Procedures on the retina and vitreous, such as vitrectomy for retinal detachment or diabetic retinopathy, are often lengthy and require a completely immobile eye. The peribulbar block provides the profound and lasting akinesia necessary for these delicate microscopic manipulations.²
• Corneal Transplantation (Keratoplasty): This procedure requires a motionless eye and excellent pain control, making the peribulbar block a suitable choice.²
• Glaucoma Surgery: Procedures like trabeculectomy, which create a new drainage channel for aqueous humor, benefit from the akinesia provided by a peribulbar block.²
• Other Surgeries: It is also useful in surgeries where an intact conjunctiva is required, such as pterygium excision with an autoconjunctival graft, as it avoids the conjunctival incision needed for a sub-Tenon's block.⁵

A Comparative Analysis: Peribulbar vs. Retrobulbar vs. Sub-Tenon's Anesthesia

The choice of regional anesthetic technique involves a trade-off between efficacy and safety. The following table provides a direct comparison of the three most common regional block techniques used in ophthalmology, synthesizing data from numerous clinical studies.

This comparison highlights that while the retrobulbar block offers the most potent effect, it does so at the highest risk. The peribulbar block was developed as a compromise, sacrificing some speed and reliability for a significant gain in safety. The sub-Tenon's block represents a further step in this direction, with an even greater safety margin due to the use of a blunt cannula, making it a popular choice for many surgeons, especially for routine cataract surgery.⁷

Considerations for Special Patient Populations

The risks associated with any needle-based block are not uniform across all patients. Certain anatomical and medical conditions significantly increase the potential for complications.

• High Myopia: Patients with high myopia (nearsightedness) often have an eyeball with a longer than average axial length (the distance from the front to the back of the eye). An axial length greater than 26 mm significantly increases the risk of the needle perforating the globe during a peribulbar or retrobulbar injection, as there is less space between the orbital rim and the back of the eye.⁶ In these patients, a sub-Tenon's or topical approach is often preferred.
• Coagulopathy and Anticoagulant Use: Patients taking blood-thinning medications (e.g., warfarin, clopidogrel, aspirin, newer oral anticoagulants) or those with underlying bleeding disorders are at an increased risk of developing a significant hemorrhage from the puncture of even a small blood vessel during a needle-based block.⁴⁵ The decision to proceed with a block in these patients requires careful consultation between the ophthalmologist, anesthesiologist, and the prescribing physician.
• Other Medical Conditions: In some cases, a peribulbar block can be an excellent choice for patients with significant systemic comorbidities. For patients with Chronic Kidney Disease (CKD), for whom general anesthesia carries higher risks, a regional block provides a safer alternative.⁴⁷ Similarly, for patients with conditions like nystagmus (involuntary eye movements), the profound akinesia provided by a peribulbar block is essential for the surgeon to operate safely, making it superior to topical anesthesia, which does not stop eye movement.⁴⁷

A Comprehensive Review of Risks, Complications, and Mitigation

While the peribulbar block was designed to be safer than its predecessor, it is not without risk. A thorough understanding of the potential complications, from common and minor side effects to rare and catastrophic events, is essential for both the practitioner and the informed patient.

Common Side Effects and Minor Complications

The most frequently encountered adverse events are generally localized and self-limiting.

• Chemosis and Lid Edema: This is a swelling of the conjunctiva (the clear membrane covering the white of the eye) and eyelid, caused by the large volume of anesthetic solution injected into the orbital tissues. It is a common occurrence with peribulbar blocks and typically resolves on its own within a day or two.⁴
• Ecchymosis (Bruising) and Subconjunctival Hemorrhage: Puncture of a small, superficial blood vessel in the eyelid or on the surface of the eye can cause bruising or a localized bleed under the conjunctiva. While visually alarming, these are usually harmless and resolve over one to two weeks.⁴⁴ The risk is higher in elderly patients and those on blood thinners.⁴⁴

Sight- and Life-Threatening Complications: A Frank Assessment

Although rare, the potential for serious complications is the primary reason for the ongoing evolution toward even safer anesthetic techniques. These events require immediate recognition and management.

• Globe Penetration or Perforation: This is the most feared local complication, where the needle inadvertently punctures the wall of the eyeball. A penetration is a single entry wound, while a perforation involves both an entry and exit wound.²⁷ The incidence is low, estimated at less than 0.1%, but the consequences can be catastrophic, leading to vitreous hemorrhage, retinal detachment, and permanent vision loss.⁴⁴ As noted, the risk is significantly higher in patients with highly myopic (long) eyes.²⁷
• Retrobulbar Hemorrhage: This occurs when the needle damages a larger artery or vein behind the eye, causing bleeding within the confined orbital space.²⁷ An arterial bleed can rapidly increase orbital pressure, causing the eye to bulge forward (proptosis) and compressing the blood supply to the optic nerve and retina. If not relieved urgently (sometimes requiring a surgical procedure called a lateral canthotomy to release the pressure), it can lead to permanent blindness.¹⁶
• Optic Nerve Damage: The optic nerve can be damaged by direct trauma from the needle tip or by secondary ischemic injury from the pressure of a retrobulbar hemorrhage.²⁶ This can result in optic atrophy and irreversible vision loss.
• Brainstem Anesthesia: This is the most severe systemic complication. It occurs when the anesthetic is accidentally injected into the subarachnoid space within the dural sheath that surrounds the optic nerve.¹⁷ From here, the anesthetic can travel directly along the nerve to the brainstem. The onset is rapid, usually within minutes of the injection, and symptoms can include drowsiness, confusion, seizures, loss of consciousness, and respiratory arrest.² While the incidence is extremely low (reported rates range from 0.006% to 0.02%), it is a life-threatening emergency that requires immediate airway management and cardiovascular support.²

Associated Pathologies: Orbital Cellulitis and Compartment Syndrome

In addition to direct complications from the injection, a peribulbar block can be associated with other serious orbital conditions.

• Orbital Cellulitis: This is a bacterial infection of the fat and muscles surrounding the eye. It can occur if skin flora are introduced into the orbit along the needle track during a non-sterile injection.⁴⁸ The trauma and bruising from the injection can create a favorable environment for bacteria to multiply. Symptoms include pain, redness, proptosis, and restricted eye movements, and treatment requires aggressive intravenous antibiotics.⁴⁸
• Orbital Compartment Syndrome (OCS): This is a vision-threatening emergency that occurs when the pressure within the rigid, bony orbit rises to a level that exceeds the perfusion pressure of the arteries supplying the retina and optic nerve, leading to ischemia.⁵³ While most commonly caused by a large retrobulbar hemorrhage following trauma, it can also be triggered by the volume of the anesthetic injection itself, especially if a bleed is also present. It requires immediate surgical decompression to prevent permanent blindness.⁵³

Enhancing Safety: The Role of Ultrasound Guidance

The most significant modern advance in mitigating the risks of needle-based blocks is the use of real-time ultrasound guidance. This technology transforms the peribulbar block from a "blind" procedure, reliant on anatomical landmarks, into a visualized one.⁵⁴ Using a small ultrasound probe placed on the eyelid, the practitioner can directly visualize the key orbital structures: the globe, the optic nerve, the muscle cone, and the needle itself.⁵⁴ This allows for precise guidance of the needle tip into the extraconal space while actively avoiding the globe and optic nerve. Studies have shown that without ultrasound, even experienced practitioners can significantly misjudge the proximity of their needle to the globe.⁵⁴ Ultrasound can also confirm the correct spread of the anesthetic solution, improving the quality and safety of the block.⁵⁴

The entire history of ophthalmic anesthesia can be viewed as a relentless drive to reduce risk by increasing safety margins and eliminating "blind" steps. General anesthesia carried systemic risks, leading to the development of regional blocks. The high-risk intraconal retrobulbar block gave way to the extraconal peribulbar block to create an anatomical buffer zone. The sharp needle of the peribulbar block, which still carried a perforation risk, was challenged by the blunt cannula of the sub-Tenon's block. Now, ultrasound guidance is being introduced to eliminate the "blind" nature of all needle-based techniques. This powerful, overarching trend demonstrates that the future of the field lies in minimizing invasiveness and maximizing certainty. The peribulbar block is a crucial and successful chapter in this story, but the narrative continues to evolve toward techniques that are either directly visualized or non-penetrating altogether.

A Guide for Patients: Preparing for and Discussing the Peribulbar Block

If you are scheduled for eye surgery, understanding the anesthetic process is a key part of your preparation. For many types of eye surgery, your doctor may recommend a peribulbar block to ensure you are comfortable and your eye remains still. This guide is designed to help you understand what to expect and how to have an informed conversation with your medical team.

The Patient Experience: From Pre-operative Assessment to Post-operative Care

The process of receiving a peribulbar block typically follows several steps:

1. Pre-operative Assessment: Before your surgery day, you will have an assessment where a nurse or doctor will review your overall health, medical history, and current medications. This is a critical step to identify any risk factors.⁵⁶
2. On the Day of Surgery: In the pre-operative area, an intravenous (IV) line may be placed in your arm or hand. This is used to give you fluids and, if you choose, a mild sedative to help you relax.⁵ You will be connected to monitors that track your heart rate, blood pressure, and oxygen levels throughout the procedure.¹⁶
3. Administering the Block: You will be taken to an anesthetic room or the operating room and asked to lie down comfortably. The anesthesiologist or surgeon will first put numbing drops in your eye. Then, the skin around your eye will be cleaned with an antiseptic solution. You will be asked to look straight ahead. You will likely feel a sensation of pressure or a dull ache as the anesthetic is injected near your eye, but you should not feel sharp pain.¹⁹ The injection itself is quick.
4. During Surgery: After the block takes effect (usually in 10-15 minutes), your eye will be numb and you will not be able to move it. During the surgery, you may be aware of lights, colors, and shadows, but you will not see the details of the operation or feel any pain.⁵⁶
5. Post-operative Care: The numbness from the block can last for several hours after surgery. During this time, you may experience double vision or have a droopy eyelid. This is normal and will resolve as the anesthetic wears off.⁵⁶ Your eye will be covered with a patch or shield for protection. You will be given instructions on how to care for your eye, including when to use prescribed eye drops. You should contact your doctor immediately if you experience severe, worsening pain after the anesthetic wears off.⁵⁶

Essential Questions for Your Surgeon and Anesthesiologist

To be an active participant in your care, it is important to ask questions. Having a clear understanding helps reduce anxiety and ensures you are making an informed decision. Consider asking your medical team the following:

• "Based on my specific eye condition and the planned surgery, why is a peribulbar block the recommended option for me?" ³³
• "What are the alternatives, such as a sub-Tenon's block or topical drops, and what are the pros and cons of each for my case?" ⁵⁸
• "Who will be performing the block, and how much experience do they have with this technique?" ⁵⁶
• "What are the most common side effects I can expect, and what are the signs of a more serious complication that I should watch out for?" ⁵⁸
• "Will I receive any sedation to help me relax during the injection and the surgery? If so, what kind?" ⁵⁶
• "Given my personal medical history, do I have any special risks I should be aware of?" ⁴⁶

The Importance of Your Medical History

Your safety is the top priority. To ensure the safest possible procedure, it is absolutely critical that you provide your medical team with a complete and accurate medical history. Be sure to discuss:

• All Eye Conditions: Tell your doctor if you are very nearsighted (myopic), have glaucoma, or have had any previous eye surgeries, especially a scleral buckle for retinal detachment. These conditions can alter the anatomy of your orbit and increase the risk of complications.²⁷
• All Medications and Supplements: Provide a complete list of everything you take, including prescription drugs, over-the-counter medications, and herbal supplements. It is especially important to mention any blood thinners, such as warfarin (Coumadin), clopidogrel (Plavix), aspirin, rivaroxaban (Xarelto), apixaban (Eliquis), or dabigatran (Pradaxa). Also mention supplements like fish oil, vitamin E, and ginkgo biloba, as these can also increase bleeding risk.⁴⁵ Your doctor will give you specific instructions on whether to stop these medications before surgery.
• Other Medical Conditions: Inform your team about any condition that might make it difficult for you to lie still and flat for the duration of the surgery. This includes a chronic cough, severe back pain, breathing problems like COPD or orthopnea, uncontrolled tremors from Parkinson's disease, or severe anxiety and claustrophobia.⁵⁶

Conclusion: The Enduring Relevance and Future of the Peribulbar Block

The introduction of the peribulbar block in 1986 was a landmark achievement in ophthalmic anesthesia. It offered a direct solution to the most pressing safety concerns of the retrobulbar block, providing a technique that significantly reduced the risk of catastrophic injury to the optic nerve and major blood vessels. For over three decades, it has served as a reliable and effective method for achieving the profound anesthesia and akinesia required for a vast range of complex eye surgeries, cementing its place as an indispensable tool for ophthalmologists and anesthesiologists worldwide.

Today, the peribulbar block is best understood not as an endpoint, but as a crucial milestone on a continuum of innovation. It remains a vital option, particularly for lengthy and complex vitreoretinal, corneal, and cataract procedures where absolute immobility is paramount. However, the field continues to be driven by the foundational principle that drove its own creation: the relentless pursuit of greater patient safety. The rise of even less invasive techniques, such as the blunt-cannula sub-Tenon's block and needle-free topical anesthesia for suitable cases, reflects this ongoing trend.

Looking forward, the future of regional ophthalmic anesthesia will likely be defined by technologies and techniques that further minimize risk by eliminating uncertainty. The growing adoption of ultrasound guidance, which transforms needle-based blocks from "blind" to visualized procedures, represents the next logical step in this evolution.⁸ The peribulbar block, therefore, maintains its enduring relevance as a critical component of the modern ophthalmic armamentarium, while also serving as a powerful testament to the medical community's unwavering commitment to refining practice in the service of safer, more effective patient care.

Visual Timeline: Key Milestones in Ophthalmic Anesthesia

• ~350 BC: Ancient Greeks, including Plato and Aristotle, document the use of the electric Torpedo ray to induce numbness for pain control.²²
• 1884: A watershed year. Dr. Carl Koller demonstrates the use of topical cocaine for surface anesthesia of the eye. In the same year, Dr. Herman Knapp describes the first injectable retrobulbar block using cocaine.⁶
• 1905: German chemist Alfred Einhorn synthesizes procaine (marketed as Novocain), the first synthetic local anesthetic, offering an alternative to cocaine.²⁹
• 1936: Dr. W.S. Atkinson publishes his standardized technique for the retrobulbar block, which becomes the "gold standard" for intraocular surgery for nearly 50 years.¹⁴
• 1967: Dr. Charles Kelman introduces phacoemulsification. This less invasive, small-incision cataract surgery reduces the need for prolonged, absolute akinesia, paving the way for less invasive anesthetic techniques.²⁹
• 1986: Drs. Davis and Mandel publish their paper on posterior peribulbar anesthesia, introducing the concept of an extraconal injection as a safer alternative to the retrobulbar block.³
• 1990s: A major shift in practice occurs. Sub-Tenon's anesthesia (using a blunt cannula) and topical anesthesia (often with intracameral lidocaine) gain widespread popularity for routine cataract surgery, driven by the desire for enhanced safety and faster visual recovery.⁶
• 1995-Present: The first studies on ultrasound-guided ophthalmic blocks are published. The use of ultrasound to visualize orbital anatomy in real-time emerges as a key technological advance to improve the safety of all needle-based blocks, including the peribulbar technique.⁵⁴

References

1. ⁹ Etymonline. (n.d.).
   Periorbital.
2. ¹³ NYSORA. (n.d.).
   Local & Regional Anesthesia for Ophthalmic Surgery.
3. ¹⁵ Unnamed Contributor. (n.d.).
   Retrobulbar and Peribulbar Blocks Overview [Video]. YouTube.
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