Topical ophthalmic anesthetics for corneal abrasions: findings from a Cochrane systematic review and meta-analysis

Despite potential benefit, outpatient use of topical ophthalmic anesthetics can result in poor healing, infection, scar, and blindness. An unbiased analysis of randomized controlled trials (RCTs) is needed to examine their effectiveness and safety compared with placebo or other treatments for corneal abrasions. Cochrane Central Register of Controlled Trials, MEDLINE, Embase.com, Latin American and Caribbean Health Sciences, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform were searched on February 10, 2023, without restriction on language or publication date. The published review protocol served as registration. Systematic review and meta-analysis of nine RCTs describing 314 participants with post-traumatic abrasions and 242 participants with post-surgical abrasions, with a median study length of 7 days (interquartile range, 7–14), show no evidence of a difference in pain control between anesthetics and placebo at 24 h in post-trauma cases. Self-reported pain at 24 h is reduced with anesthetics plus topical nonsteroid anti-inflammatory drug in post-surgical participants (mean difference [MD], −5.72 on a 10-point scale; 95% CI, −7.35 to −4.09; 1 RCT; 30 participants) and at 48 h with anesthetics alone in post-trauma participants (MD, −5.68; 95% CI, −6.38 to −4.98; 1 RCT; 111 participants). Anesthetics are associated with 37% increased risk of non-healing defects (risk ratio, 1.37; 95% CI, 0.78 to 2.42; 3 RCTs; 221 post-trauma participants). All evidence is of very low certainty. Over 50% of trials have an overall high risk of bias. Available evidence is insufficient to support outpatient use of topical anesthetics for corneal abrasions with respect to pain, re-epithelialization, and complication risk. The cornea is the clear, dome-shaped structure within the eye that covers the colored part of the eye. It is one of the most pain-sensitive tissues in the body and damage to the top layer of the cornea is the cause of over 10% of all eye-related visits to emergency rooms in the USA. This layer is also removed in some eye surgeries. Topical anesthetic drops can be used as a treatment however, they can be habit-forming and can cause corneal scar or blindness. We analyzed 9 randomized controlled trials and found that topical anesthetics were not shown to reduce pain, improve healing, or decrease the chance of complication compared with placebo. We thus do not recommend their use to treat corneal damage. Leslie et al. assessed the evidence available in randomized controlled trials on outpatient treatment of corneal abrasions using topical anesthetic agents. They found the evidence regarding the effects of topical anesthetics on pain, re-epithelialization, or complication risk is insufficient to recommend its outpatient use.