Conventional teaching is that while effective at reducing pain, prolonged use of topical anesthetics leads to poor wound healing of the corneal epithelium, and potential development of badness such as corneal ulcers down the line.
Where does that dogma actually come from, and does that really mean your patient's eyeball is going to melt off immediately if you slip them a bottle of tetracaine to take home?
Let's look at some cold, hard facts, courtesy of Rebel EM:
As you can see, these were all small case reports or case series. More importantly, in all but one case, the patients with adverse outcomes were abusing topical anesthetics for weeks/months, at higher concentrations than those typically used today.
In recent years, there have been a slew of newer studies from both emergency and ophthalmology literature attempting to refute this dogma. A systematic review of these studies was published in 2015 by Swaminathan et al. in JEM, titled "The Safety of Topical Anesthetics in the Treatment of Corneal Abrasions: A Review."
- This included 2 ED-based, randomized, double blind, placebo-controlled studies on human patients with corneal abrasions.
- There were also 4 studies on patients who underwent photorefractive keratectomy (PRK), an ophthalmologic procedure similar to LASIK where a corneal incision is made, kind of like a corneal abrasion.
- All 6 studies demonstrated that a short course of dilute topical anesthetic provided efficacious analgesia without adverse effects or delayed epithelial healing.
A separate observational chart review in Annals from 2017 by Waldman, et al. looked at 1576 corneal abrasions, 533 of which were simple, who were treated with topical tetracaine 1% for 24 hours.
- Simple was defined as: not large, penetrating, or lacerating, with onset within 2 days from a simple traumatic cause, excluding chemical exposure, contact lens use, infection, retained foreign body, or other contamination.
- 57% of the simple corneal abrasions were given tetracaine, and 14% of non-simple corneal abrasions also received tetracaine.
- While there were ZERO serious complications for ANY patient given 24 hr of tetracaine, the authors did find a slight increase in the number of repeat ED visits in non-simple corneal abrasion pts who were given tetracaine.
Bottom line:
1) Short-term use of dilute topical anesthetics for simple corneal abrasions for 24-48 hrs is definitely effective and most likely safe, as shown by several recent small but well-designed randomized controlled studies.
2) The risk and safety concerns associated with the use of topical anesthetics is likely overstated, and come from poorer quality evidence such as experimental animal studies, case reports, and case series.
3) At the same time, larger studies should be undertaken to assess safety before the widespread use of this pain management modality can be recommended.
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