Mythbusting 1 - Corneal Abrasions and Topical Anesthetics

Nilesh P., D.O. -

Hey Swami, Mel,

Nice piece. What about tetanus in corneal abrasions? I feel this is not necessary and there is some data that agrees. However, it is common practice to give tetanus for corneal abrasions.

Nilesh

Anand S., M.D. -

Nilesh - Probably not necessary but I've always seen it as a public health issue. It's an opportunity to make sure people are up to date on tetanus. Additionally, we can booster immunity to pertussis.
Much of my take on this comes from my boss who saw lots of patients presenting with tetanus in the 70's and pushed for tetanus prophylaxis in the ED back then.

Nilesh P., D.O. -

Great, thanks. I'd be interested in hearing about his cases of tetanus as many of us will now never see.

Nilesh

Silver Surfer -

It would have been interesting to hear about topical diclofenac and ketorolac as alternatives. In my area topical nsaids, not proparacaine, are used after LASIK.

Anand S., M.D. -

@Silver Surfer - I have read some of the lit on topical NSAIDs from the ophtho literature and seems relatively safe but there are no studies on the us of those meds in corneal abrasions in the ED so can't recommend using them at this time.

Cherry L. -

Wow, I have caused quite a furore at the specialty ophthalmological hospital I'm currently working at by bringing this up. They have a blanket ban on giving patients minims (literally contain 5 drops) of topical anaesthetic to go home with for anything. Those who disagree mostly say, "you can't trust them not to keep self-administering". I suggested it was quite paternalistic in this age of shared-decision making and perhaps they'd like to offer their patient that choice. That didn't go down so well.

Anand S., M.D. -

I'm surprised since they use topical anesthetics so liberally after things like PRK. I agree that being so paternalistic is dangerous. We routinely give patients far more dangerous medications and trust them to take them properly. I would argue that there's as much potential to misuse the handful of opiates we give for corneal abrasions with potentially worse outcomes.

Matt B. -

Just tried to get the okay from my Peds EM attending for this in a 10-year-old with autism who won't understand to not keep rubbing and scratching his corneal abrasion. Literally was laughed at by multiple attendings saying that this will never change even after showing them this and explaining the diluted method. Looks like this myth is in pretty deep.

Anand S., M.D. -

Matt - I'm sorry to hear that your attending wasn't more open to the idea. Here's a case where it would have clearly had some benefit.
These myths and urban legends really are ingrained in our minds. The tough part is, how much can you push as a resident. It's our job as educators to be open to new information. In this case, we have dogma with no evidence versus a single good study. It's difficult to do but I challenge the naysayers to show me the evidence of what they are arguing. The onus should be on all of us critically look at these issues.
I commend you for taking the time to read the literature that's out there. At some point, you'll have to decide what you think is best for the patient. This is just practice for that time.

Jennifer M. -

I am currently on optho and heard this while driving home from optho rotation. The next day I brought this up with my attendings and talked about the cases discussed on emrap. The group I am with said that they never give out tetracaine after prk and said the reason you should never give it with say a corneal abrasion is that it anesthetizes the nerve. They said with anesthetics the nerve cannot function and you need nerve function to epithelialize the cornea for healing. Without good epithelialization, they said you can get corneal ulcers. Any thoughts?

Anand S., M.D. -

Interesting. None of the publications on this topic cited this as the reason for why you should not give topical anesthetics. They all site that the drug itself can inhibit epitheliaztion but not via suppression of the nerve. They also note direct cytotoxic effects. None of these are substantiated in the literature but they are taught over and over again. I would simply ask for the references and I'd be interested to see what they find. Thanks!

Kenneth K., M.D. -

medical practice so often makes no sense. we have a drug that really does not show any harm, is highly effective and everyone says not to give it. instead we give other drugs, such as narcotics which are not particularly effective, addictive and are clearly dangerous when misused (some states have more deaths from narcotic overdose than car accidents). if you can't trust the patient to use the medication correctly then narcotics are the more dangerous choice. anyway, thanks for the interesting lecture.

Anand S., M.D. -

Ken - Completely agree. I would like to see a larger study but if that pans out, I see no reason not to trust our patients with this medication.

Jennifer M. -

Dr. Swaminathan,
Thank you so much for your reply. I did bring into to optho the next day. One ophthalmologist, showed me on the american academy of ophthalmology website that "toxicity from chronic use of topical ocular meds also may cause nerve damage and result in corneal anesthesia. Indeed, topical anesthetics are a well known cause of neurotropthic keratopathy. Interesting, though as their own literature states "chronic"use and in this instance we would not be using them chronically.
Another optho, let me borrow his book - External Disease and Cornea, Section 8, Basic and Clinical Science Course, from American academy of Opthalmology, 2006-2007, p. 102-109. In it, they mention that "neurotrophic keratopathy results from damage to CN V, which causes corneal hypoesthesia or anesthesia. They reference three articles that this section of the book is based on. One is on genetics. :
Brunt, PW, McKusick, VA, "Familial dysautonomia: a report of genetic and clinical studies, with a review of the literature. Medicine. 1970; 49: 343-374.
Goins, KM. New Insights into the diagnosis and treatment of neurotrophic keratopathy. the Ocular Surface. 2005; 3:96-110.
Muller, LJ, Marfurt CF, Kruse, F, et. al. Corneal nerves: structure, contents and function. Exp Eye Res. 2003; 76:521-542.
I continued to look at another section of the book on Topical Anesthetic abuse, where it is discussed that anesthetics inhibit epithelial migration and division. They suggest looking for abuse of anesthetics when corneal abrasions fail to heal or infectious keratitis does not respond to appropriate therapy. I still do not feel these ophthalmology resources answer the specific question you asked. Thanks for an interesting topic of discussion. I look forward to hearing your thoughts and suggestions on this and sorry it was so long.

Anand S., M.D. -

Great stuff Jen! Nice job going to the "source" literature on the topic. I think we again see the urban legend passed down with minimal or no literature to defend the dogma. Thanks for the great work!

Jennifer M. -

No problem. Thanks for being a great teacher, Dr. Swaminathan.

Neil W., M.D. -

Dr Orman and Dr. Swaminathan-

Please look at upcoming Academic Emergency Medicine issues this spring
I just completed a randomized control trial using topical tetracaine vs saline for corneal abrasions in New Zealand that has been accepted for publication.

we had over 50 patients in each group and 100% follow up and there were no complications!!!

Neil Waldman

Anand S., M.D. -

Neil - That's great news. More evidence to debunk the urban legend. Rob and I will keep our eyes out and maybe we can do a little lit update on this.

Rakesh S., M.D. -

After listening to this, I told my pharmacist to get me " single dose' vial for tetracaine and I had it within 5 days. Being in small rural community ER for almost a decade has an advantage - getting medical staff approval was real easy. The brand I use is TETRAVISC. The only draw back is that its viscus. Its one ml vial with 6-7 drops in it. I have used in 2 patients so far, and followed up both patients. Both ulcers healed. One patient actually did not use it at all. ( He said he did not like the " thick" stuff.)

Rakesh S., M.D. -

Please correct - it was abrasion not ulcer.

Anand S., M.D. -

Rakesh - Great to see the application to actual clinical care. Thanks for sharing this with the EMRAP community.

David K. -

Looking back to post on tetanus for corneal abrasions from Nilesh.

The only study on this was on mice in 1993. They looked at mice (which were unimmunized) that had corneal abrasions, penetrations, perforations. None of those with abrasions or penetration got tetanus, and 1/3 of those with perforation did.
Small study, and on mice. No humans. It is what it is, but definitely not support for tetanus prophylaxis in all.
Review done in 2003 (Emerg Med J 2003;20:61–67). They only had the one study to look at.
Thats it.

Anand S., M.D. -

The tetanus side of this is sketchy. I think we do it more for the public health benefit of keeping tetanus status up to date and the added benefit of pertussis immunization updating.

Matt B. -

Ask and ye shall receive.

Short-Term Tetracaine Does Not Impair Healing of Corneal Abrasions
Ali S. Raja, MD, MBA, MPH, FACEP Reviewing Waldman N et al., Acad Emerg Med 2014 Apr 21:374
Patients with corneal abrasions treated with tetracaine after ED discharge had similar outcomes to those treated with saline.

http://onlinelibrary.wiley.com/doi/10.1111/acem.12346/pdf

At least it's a start.

Allen L., M.D. -

One of my partners, an EMRAP subscriber, sent a patient home on topical anesthetic drops for a corneal abrasion. She returned 4 days later and had significantly overused the drops. She had a large corneal lesion and was in terrible pain. When I called the corneal expert ophthalmologist to discuss this, his first words after a pregnant pause included his criticism of this practice and the word "malpractice". Once he calmed down, here is his email response after I forwarded him both the audio file and the text summary document.

I finally got to look at the info you sent me. As a corneal specialist I have seen many cases of corneal damage from topical anesthetic abuse. Some cases requiring tarsorrhaphy and transplantation. Your patient was the most recent case of anesthetic abuse with corneal toxicity. She had a worsening epithelial defect, stromal edema with a ring infiltrate. The epithelial defect healed after discontinuing the anesthetic drops. The ring infiltrate and stromal haze will hopefully improve with time.
Topical anesthetics provide at most 15 minutes of corneal anesthesia. Dosing qid would provide 1 hour of relief over a 24 hour period. Patients often exceed the recommended dose for obvious reasons. A better option would be the addition of an NSAID topical depending on the pain threshold of the patient. Topical anesthetic use requires close followup by an ophthalmologist and in my opinion should not be given by the DEM.
I will present this issue to the Ophthalmology sub committee and come up with some recommendations for the DEM personnel treating eye patients.

Food for thought. I am not going to do this yet.

Allen

Anand S., M.D. -

Allen - thanks for the case and the comments.

Tough case with a bad outcome. And I agree with you that this is not what I would do either. Topical anesthetics must be respected. The case reports Rob and I reviewed showcase the fact that there is potential for harm when used incorrectly. However, we give patients plenty of dangerous medications and trust that they take them appropriately. The difference between treatment and poison is simply dose. The drops must only be given to patients we believe will use them properly and should be given with proper instructions. I only send people home with 1 days worth (1-2 ml of 0.05%) so that they can't use it Q15 minutes for days on end. If they need the drops longer than 24 hours or so, it's likely that more than a simple abrasion is going on. That's why 24 hour follow up is needed for abrasions.
I certainly sympathize with your partner and advise caution with using this as I would with using opiates for pain relief.

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