It seems to me that these researchers asked the wrong question. Most of us know that numbing up a corneal abrasion relieves pain. But the big question has always been is it safe to send patients home with topical anaesthetic. For decades, ophthalmologist have been telling us it is dangerous. But lately, this dogma has been challenged with better quality research.
So if they didn't ask the right questions, then why was this study conducted and published in our peak emergency medicine journal?
It turns out we have never proven the efficacy of topical anaesthetics for outpatient treatment of simple corneal abrasions with an RCT. Go figure...
But, now we have.
This well conducted RCT out of a single ED in Oklahoma (yeeeehaaaaaaa!) randomised 111 patients to 2ml’s of tetracaine drops vs placebo to take home. The primary outcome was the overall NRS pain score at a 24-hour and 48-hour ED follow-up.
As expected, the tetracaine worked marvellously. Pain score was 1/10 in the tetracaine group and 8/10 in the placebo group. This is a huge difference with lots of pretty p values. The placebo group also gulped down more Vicodin than the those given tetracaine (don’t get me started…)
Unfortunately, we cannot make claims about safety with so few trial participants. A much larger study will be needed to find less common side effects. But the original studies that suggested harm are old and poor quality. It seems that the current best evidence suggests topical anaesthetics are probably safe and definitely effective for simple corneal abrasions.
But don’t be surprised if your local ophthalmologists disagree… it's hard to teach an old dog(ma) new tricks.
Shipman S, Painter K, Keuchel M, et al. Short-Term Tetracaine is Highly Efficacious for the Treatment of Pain Caused by Corneal Abrasions: A Double-Blind, Randomized Clinical Trial. Ann Emerg Med. 2020 Oct 27;S0196-0644(20)30739-3. doi: 10.1016/j.annemergmed.2020.08.036 [link to article]