Ophthalmic surgery is one of the most common surgical fields requiring anesthesia in developed countries; in the United States alone, over 3 million cataract lenses are extracted annually 1. In the future, ophthalmic surgeries will only continue to increase in frequency given the high incidence of age-related ophthalmic ailments in an overall aging population 2,3.
Either topical, regional or general anesthesia can be used for eye surgery, depending on patient background and clinical context. Topical anesthesia usually involves the administration of a topical anesthetic such as xylocaine, paracaine, tetracaine, or bupivacaine 4; however, it remains limited by its tendency to trigger allergies, endothelial and epithelial toxicity, or keratopathy. Local anesthesia is usually preferable for ophthalmic surgery since it is economical, safe, easy, has a rapid onset, and yields a dilated pupil with low intraocular pressure, in addition to incurring minimal post-operative restlessness, lung complications, and bleeding. Regional anesthesia can be used for nearly all eye surgeries, such as keratoplasty, cataract extraction, glaucoma, iridectomy, strabismus, and retinal detachment surgeries. For regional anesthesia as such, the conjunctiva, globe and orbicularis are paralyzed by a combination of surface and facial anesthesia, alongside, traditionally, a retrobulbar block. Rarely used, general anesthesia is preferred for ocular surgeries in anxious individuals, psychiatric patients, and youth – as well as for major surgeries such as exenteration or perforating ocular injuries. In such contexts, general anesthesia is advantageous in that it results in total akinesia, controlled intraocular pressure, and a safe operating environment.
In the past decade, as a result of drastic technological improvements, the practice of ophthalmic anesthesia has been transformed. In general, vast improvements have been made to minimally invasive surgery, primarily for glaucoma and cataracts 5–7, by refining smaller incisions for surgery. These improvements have laid the foundation for multiple changes to surgical and anesthesia approaches for opthalmic surgery.
First, resorting to general anesthesia is increasingly infrequent. Second, phacoemulsification techniques have gained prominence in light of their ability to facilitate the conduction of cataract surgery under topical anesthesia and to avoid the venous air embolisms that can be caused by suture-free vitrectomy ports; their advent has resulted in topical anesthesia representing a viable alternative for most cataract surgeries. Third, the sub-Tenon’s blockhas gained popularity given its ability to produce satisfactory anesthesia for most intraocular procedures and its circumvention of the inherent risks of needle-based blocks, including globe perforation and optic nerve injury. It is primarily used for cataract surgery but remains effective in a variety of other eye surgeries, including strabismus correction, vitreoretinal surgery, and trabeculectomy 8. Finally, the retrobulbar block has been largely replaced by the peribulbar approach 9, whereby needles are kept at a greater distance from vital adnexa and globe. Since peribulbar anesthesia has a prolonged latency of action, it is preferable to perform the block at least ten minutes prior to the start of surgery; these are increasingly performed in the holding room to increase efficiency.
In parallel, certain surgical techniques have also emerged as useful additions to these surgical approaches. For example, ultrasound-guided eye blocks have proven useful during ophthalmic surgeries. The potential benefits of ultrasound guidance include the real-time visualization of needle trajectory, thereby minimizing the chance of globe perforation 9, and the tracking of anesthetic spread, thereby improving the quality and safety of blocks. In the same vein, hyaluronidase, despite its allergenicity, has emerged as a useful adjuvant during surgery for its promotion of local anesthetic diffusion and hastening of block onset time. Teaching curricula will have to be updated to ensure the complete training of anesthesiologists as the field evolves 9. Of critical importance in light of an aging population, anesthesia strategies in ophthalmic surgery ostensibly continue to rapidly progress and dynamically adapt to ongoing technological advancements.
References
1. Cullen KA, Hall MJ, Golosinskiy A. Ambulatory surgery in the United States, 2006. Natl Health Stat Report. 2009.
2. Colby SL, Ortman JM. Projections of the Size and Composition of the U.S. Population: 2014 to 2060. Program. 2014.
3. Swenor BK, Ehrlich JR. Ageing and vision loss: looking to the future. Lancet Glob Heal. 2021. doi:10.1016/S2214-109X(21)00031-0
4. Local Anaesthesia for Eye Surgery. https://web.archive.org/web/20121025132106/http://www.nda.ox.ac.uk/wfsa/html/u12/u1205_01.htm.
5. Yang S-A, Mitchell W, Hall N, et al. Trends and Usage Patterns of Minimally Invasive Glaucoma Surgery in the United States. Ophthalmol Glaucoma. 2021. doi:10.1016/j.ogla.2021.03.012
6. Singh K, Misbah A, Saluja P, Singh A. Review of manual small-incision cataract surgery. Indian J Ophthalmol. 2017. doi:10.4103/ijo.IJO_863_17
7. De Gregorio A, Pedrotti E, Russo L, Morselli S. Minimally invasive combined glaucoma and cataract surgery: clinical results of the smallest ab interno gel stent. Int Ophthalmol. 2018. doi:10.1007/s10792-017-0571-x
8. Guise P. Sub-Tenon’s anesthesia: An update. Local Reg Anesth. 2012. doi:10.2147/LRA.S16314
9. Palte HD. Ophthalmic regional blocks: Management, challenges, and solutions. Local Reg Anesth. 2015. doi:10.2147/LRA.S64806