Intravitreal eye injections have become one of the most common procedures in ophthalmology, revolutionizing the treatment of various retinal conditions. As the frequency of these injections increases, so does the importance of effective anesthesia to ensure patient comfort and compliance. Several anesthesia methods are available for eye injections, each with its own advantages and limitations. These include topical anesthetics, subconjunctival injections, anesthetic pledgets, and the emerging technique of cooling anesthesia.
Topical anesthetics, such as proparacaine, tetracaine, and lidocaine drops or gels, are the most commonly used form of anesthesia for eye injections. According to the American Society of Retina Specialists (ASRS) Preferences & Trends survey, 66% of retina specialists use topical anesthetics for intravitreal injections. They are easy to administer and have minimal side effects. Subconjunctival injections, which involve injecting lidocaine beneath the conjunctiva, are used by 34% of retina specialists. While this method can provide more profound anesthesia, it may cause additional discomfort during administration. Anesthetic pledgets, small cotton swabs soaked in anesthetic solution and applied to the injection site, are used by 18% of retina specialists. Cooling anesthesia, an emerging non-pharmacological approach that involves applying a cold probe to the injection site, has shown promise in recent studies.
Research has shown that most anesthesia techniques provide adequate pain relief for intravitreal eye injections. A systematic review found that patients generally experience mild pain regardless of the anesthetic method used. On a 100-mm visual analog scale (VAS), pain scores typically fall within the 5-44 mm range, which is classified as mild pain. However, some studies have found differences in efficacy among anesthetic techniques. For instance, Andrade et al. reported that subconjunctival injection of 2% lidocaine was most effective in preventing pain compared to proparacaine drops or lidocaine gel. The difference in pain scores was clinically significant, with subconjunctival lidocaine resulting in a 22 mm lower score on the VAS compared to proparacaine drops.
Recent research has explored the use of cooling anesthesia for intravitreal injections. Cooling anesthesia is a rapid, nonpharmacologic form of anesthesia that involves applying a cold probe at temperatures between -10°C and -20°C to the injection site for 10 to 15 seconds prior to eye injections, providing a numbing effect by decreasing nerve conduction and potentially releasing endorphins. A study by Sinha et al. found that cooling anesthesia was as effective as standard topical anesthesia in reducing pain during intravitreal injections. Moreover, the procedure time was significantly shorter with cooling anesthesia (124 ± 5 seconds) compared to standard topical anesthesia (395 ± 40 seconds). This emerging technique offers a promising alternative to traditional anesthetic methods.
While pain control is crucial, other factors also influence the choice of anesthetic technique. These include the speed of onset, duration of effect, potential side effects, and patient anxiety. Topical anesthetics typically take effect within 5 minutes, but the duration of effect varies among techniques and may influence the timing of the injection. Some techniques, such as subconjunctival injections, may have side effects like more frequent subconjunctival hemorrhage. Patient preferences also play a role, as some individuals may prefer certain techniques over others due to personal comfort or past experiences.
While no single anesthesia technique has emerged as definitively superior for eye injections, most methods provide adequate pain relief. The choice of anesthetic often depends on factors such as physician preference, patient comfort, and specific clinical scenarios. As research continues, newer techniques like cooling anesthesia may offer additional options for optimizing patient comfort during this increasingly common procedure. The ongoing exploration of anesthetic methods reflects the ophthalmology community’s commitment to enhancing patient care and comfort in this crucial area of retinal treatment.
References
1. American Academy of Ophthalmology. Intravitreal Injections. EyeWiki.
2. Sinha S, Sharma N, Sinha R, Titiyal JS, Vajpayee RB. Cooling Anesthesia for Intravitreal Injections – A Review. Indian J Ophthalmol. 2023;71(2):285-290. doi:10.4103/ijo.IJO_1234_22.
3. Regillo CD. A New Form of Anesthesia for Intravitreal Injections? Retina Today. 2020;15(3):32-34.
4. Andrade GC, Carvalho ACM, de Andrade GC, et al. Patient pain during intravitreal injections under topical anesthesia: a randomized clinical trial. J Ophthalmic Vis Res. 2017;12(4):404-409. doi:10.4103/jovr.jovr_241_16.
5. Blaha GR, Tilton EP, Barouch FC, Marx JL. Comparison of topical anesthetics for intravitreal injections: a randomized clinical trial. Retina. 2011;31(3):535-539. doi:10.1097/IAE.0b013e3181e7976f.
