Ophthalmic surgery presents unique challenges to the anesthesiologist [1]. The patient population varies widely, from an infant requiring strabismus surgery to an elderly patient requiring cataract surgery [1]. It is not uncommon for patients with rare genetic syndromes to present for eye surgery [2]. Since most patients undergoing ophthalmic surgeries are elderly with multiple comorbidities, such as diabetes and hypertension, thorough preoperative evaluation and preparation are necessary to minimize perioperative complications [1,2]. Proper administration of anesthesia during ophthalmic surgery demands a knowledge of ocular physiology, intraocular pressure management, ocular and systemic effects of common medications, the oculocardiac reflex, and intraocular gas expansion [1]. 

Today, the majority of ophthalmic surgeries are performed as day cases under topical or regional anesthesia with or without intravenous sedation [2]. Until the early 1990s, regional anesthesia for ophthalmic surgery generally consisted of a retrobulbar block combined with a block of the facial nerve [4]. This method of anesthesia came with a significant risk of retrobulbar hemorrhage, perforation of the globe, and damage to surrounding nerves and blood vessels [4]. In order to prevent these adverse effects, the use of a combined peribulbar and retrobulbar technique, known as the peribulbar method, soon became the popular method of producing ocular anesthesia [3,4]. Complications associated with the peribulbar technique are lower. 

The peribulbar method involves larger quantities of local anesthetic solution and volumes up to 20 mL may be used [4]. A 50:50 mix of 2% lidocaine and 0.5% levobupivacaine is the most frequently used anesthetic agent [3]. Before administering local anesthesia, the patient is placed in a supine position and the eye is cleaned with antiseptic solution [3,4]. Topical anesthesia is used to initially obtain globe surface anesthesia [3]. Iodine 5% is applied to the conjunctiva to ensure splashes do not enter the contralateral eye [3]. The injection of the anesthetic agent can be made either through the skin or through the conjunctiva after application of iodine 5% [3,4]. Normally, three injections of local anesthesia give a consistently adequate result [3]. Regional anesthesia is considered safe and well tolerated by patients [3].  

Although local anesthesia is now the main anesthetic technique for ophthalmic surgery, there is still a need for general anesthesia in some circumstances [3]. Patients may refuse local anesthesia, be unable to keep still during the duration of the surgery, or lack the mental facility to cooperate while awake [5]. Intraoperative patient movement is the leading cause of both eye injury and anesthesiologist liability for ophthalmic procedures [1]. The American Society of Anesthesiologists found that 30% of claims for eye injuries associated with anesthesia were related to patient movement during surgery [5]. Therefore, young children are frequently put under general anesthesia for ophthalmic surgery [5]. 

General anesthesia can be achieved with a combination of intravenous and inhalation agents, with or without muscle relaxants and opiates [2]. Current research finds that remifentanil and propofol total intravenous anesthesia (TIVA) provide optimal conditions for ophthalmic surgery [2]. TIVA has the advantage of causing less postoperative nausea and vomiting, reduced stress response due to airway intervention, faster recovery, and smoother emergence [2]. Muscle relaxants are not usually required if TIVA is used [5]. General anesthesia has the advantage of providing good control of intraocular pressure and being easy to adapt to specific surgical requirements [4]. 

Overall, ophthalmic surgery is relatively low risk [3]. The majority of ophthalmic procedures are well tolerated and produce few, if any, postoperative side effects, regardless of the type of anesthesia administered [2].  

References 

1. Berry, S., & Ligda, K. O. (2015). Ophthalmic surgery. Basic Clinical Anesthesia, 483-487. doi:10.1007/978-1-4939-1737-2_36 
2. Young, S., & Basavaraju, A. (2019). General anaesthesia for ophthalmic surgery. Anaesthesia & Intensive Care Medicine, 20(12), 716-720. doi:10.1016/j.mpaic.2019.10.005 
3. Fulton, R., & Urquhart, C. (2019). Regional anaesthesia for eye surgery. Anaesthesia & Intensive Care Medicine, 20(12), 725-727. doi:10.1016/j.mpaic.2019.10.003 
4. Mirakhur, R., & Elliott, P. (1992). Anaesthesia for ophthalmological surgery. Current Anaesthesia & Critical Care, 3(4), 212-217. doi:10.1016/0953-7112(92)90006-l 
5. Pritchard, N. (2017). General anaesthesia for ophthalmic surgery. Anaesthesia & Intensive Care Medicine, 18(1), 33-36. doi:10.1016/j.mpaic.2016.10.010