EBM Lecture Handout #2: Topical Anaesthetics fo Corneal Abrasions

A summary of the evidence supporting the use of topical anesthetics for pain control in simple corneal abrasion after emergency department discharge

Your patient’s child poked him in the eye, and now he is in the most excruciating pain of his life. After a thorough eye exam, you determine he has a simple corneal abrasion. Your patient is ready for discharge, and has actually been pain free ever since you but 2 drops of tetracaine in the affected eye. “Hey, can you give me some of those amazing drops? They really worked!” You look down at this poor soul, and for some reason you say “no”.

Why don’t we use topical anesthetics for pain control in patients with simple corneal abrasions?

History

There are a handful of case reports and case series that report corneal damage related to topical anesthetic use.

Epstein DL, Paton D. Keratitis from misuse of corneal anesthetics. N Engl J Med. 1968;279:(8)396-9. PMID: 4232838

This is a case series of 5 case reports. All 5 were patients who applied topical anesthetics for prolonged periods of time:

  • The first case used 5% tetracaine (most preparations in the emergency department are only 0.5%). The patient used it every hour for three weeks and developed an ulcer.
  • The second case used 0.5% tetracaine every 20 minutes for two months.
  • The third case was a veterinarian who used veterinary tetracaine in an unknown concentration, every 1-2 hours for two weeks.
  • The fourth case was a pediatrician who used it every 16 minutes for 5 days.
  • The last case was a patient who used it 10 times a day for three months.

Willis WE, Laibson PR. Corneal complications of topical anesthetic abuse. Can J Ophthalmol. 1970;5:(3)239-43. PMID: 5472832

This another case series, this time with 9 cases, again all with chronic abuse of the topical anesthetics. For example, one case was a doctor who used tetracaine 0.5% every 15 minutes for seven days. Another was a woman who used 8 bottles of proparacaine over 6 weeks. It’s not clear that the aesthetics actually caused any of the findings – the increased used of anesthetic could just have been because of a more severe or complicated underlying disease in the first place. There were also no long term problems as a result of the anesthetics. All the symptoms completed resolved on follow up (after the aesthetics were stopped).

Duffin RM, Olson RJ. Tetracaine toxicity. Ann Ophthalmol. 1984;16:(9)836, 838. PMID: 6508100

This is a single case report describing an ulcer in a patient using tetracaine ointment for 2 months. Again, there is no clear causation and the use was obviously prolonged.

Chern KC, Meisler DM, Wilhelmus KR, Jones DB, Stern GA, Lowder CY. Corneal anesthetic abuse and Candida keratitis. Ophthalmology. 1996;103:(1)37-40. PMID: 8628558

This is another case series, this time of 4 patients. All of these patients had chronic use of topical anesthetics.

Wasserman BN, Liss RP, Santander SH. Recurrent corneal ulceration as late complication of toxic keratitis. Br J Ophthalmol. 2002;86:(2)245-6. PMID: 11815357

A final case report of a single patient using proparacaine hourly for 2 weeks.

Bottom line: In rare cases, topical anaesthetics may cause corneal damage. (Causality cannot actually be demonstrated from these case reports). However, in none of these cases were the drops used as prescribed. They were all examples of chronic abuse.

In contrast, ophthalmologists often allow their patients to use topical anaesthetics after procedures.

Considering that the evidence that these drops harmful is exceedingly weak, it would be reasonable to consider any studies looking at the the safety of these drops. There are a few studies in the ophthalmology literature with patients who received photorefractive keratectomy and were given topical anaesthetic agents for between 24 and 72 hours postoperatively. The healing was evaluated initially and at 72 hours. All three studies agreed there was no difference in corneal healing at 72 hours and no complications were identified.

Shahinian L, Jain S, Jager RD, Lin DT, Sanislo SS, Miller JF. Dilute topical proparacaine for pain relief after photorefractive keratectomy. Ophthalmology. 1997;104:(8)1327-32. PMID: 9261322

This study had two parts. Part 1: They exposed healthy volunteers to differing strengths of topical anesthetics, including 10 patients to 0.05% proparacaine q15min for 12 hours, then q1h for 12 hours on days 2-7. No ulcers occurred. Part 2: This was a double blind, placebo controlled RCT including 34 patients. The topical anesthetic group had decreased pain scores, longer pain relief, and less opioid use. There were no complications.

Brilakis HS and Deutsch TA. Topical tetracaine with bandage soft contact lens pain control after photorefractive keratectomy. J Refract Surg. 2000 Jul-Aug;16(4):444-7. PMID: 10939724

This is a prospective observational trial of a single surgeon’s practice.  To control surgical pain, 69 eyes belonging to 49 patients were included in the study, and all were given 10 drops of 0.5% tetracaine. There were no complications and no prolonged re-epithelialization. The author’s conclusion is: “limited use of topical anesthetics is an effective and safe analgesic option after PRK. Use of tetracaine in this protocol did not prolong the time to re-epithelialization. Giving only a limited amount of tetracaine to patients prevents abuse and toxicity to the cornea while managing severe pain.”

Verma S, Corbett MC, Marshall J. A prospective, randomized, double-masked trial to evaluate the role of topical anesthetics in controlling pain after photorefractive keratectomy. Ophthalmology. 1995;102:(12)1918-24. PMID: 9098296

This is a randomized, double-blind, placebo controlled RCT that included 44 postoperative patients and compared 1% tetracaine to placebo. The anesthetic group had better pain control and there were no differences in epithelial healing and no complications.

Verma S et al. A comparative study of the duration and efficacy of tetracaine 1% and bupivacaine 0.75% in controlling pain following photorefractive keratectomy (PRK). Eur J Ophthalmol. 1997;7(4):327-33. PMID: 9457454

This is a prospective RCT of 38 patients comparing 1% tetracaine with 0.75% bupivacaine. There were no differences between the two groups. There was full epithelial closure in all patients at 72 hours.

Emergency Department Studies

Ball IM, Seabrook J, Desai N, Allen L, Anderson S. Dilute proparacaine for the management of acute corneal injuries in the emergency department. CJEM. 2010;12:(5)389-96. PMID: 20880433

This is a small (33 patient) placebo controlled RCT. They compared 0.05% proparacaine (2-4 drops PRN to a max of 40 drops) to placebo. The patients had follow-up with ophthalmology on days 1,3 and 5. The topical anesthetics resulted in better pain control and decreased opioid use. There were no complications.

Ting JY, Barns KJ, Holmes JL. Management of Ocular Trauma in Emergency (MOTE) Trial: A pilot randomized double-blinded trial comparing topical amethocaine with saline in the outpatient management of corneal trauma. J Emerg Trauma Shock. 2009;2:(1)10-4. PMID: 19561949 [free full text]

This is a small (47 patients) double blind RCT of 0.4% amethocaine in patients discharged from the ED with corneal abrasions. The study had very poor follow up (7/22 in amethocaine group and 9/25 in the placebo group). There were no differences in anything between the groups, including satisfaction, analgesia, or need for reassessment. The authors note more corneal defects at 36-48 hours in the amethocaine group, but it was 2/7 versus 1/9 patients (p=0.3) who actually followed up, making any conclusion meaningless.

Waldman N, Densie IK, Herbison P. Topical tetracaine used for 24 hours is safe and rated highly effective by patients for the treatment of pain caused by corneal abrasions: a double-blind, randomized clinical trial. Acad Emerg Med. 2014;21:(4)374-82. PMID: 24730399 [free full text]

This is a double blind, placebo controlled RCT of 116 patients with simple corneal abrasions. They compared tetracaine 1% versus saline, q30min prn for 24 hours. There were no complications. Pain scores were the same between groups, but satisfaction was higher in the tetracaine group. I don’t really know what that means.

Bottom line

Corneal abrasions are extremely painful. Patients deserve a good analgesic strategy. Topical anesthetics may cause occasional problems in patients who abuse them, but there is no evidence that they are harmful if used for a short period of time (typically corneal abrasions heal within 24-48 hours). At this point there is not enough evidence to definitively prove that they are safe, however, I don’t think there is any convincing evidence that a short course could be harmful. I think these medications are reasonable to use for reasonable patients.

So personally, my practice is to offer 24 hours of topical anesthetics to all patients with simple corneal abrasions. I think simple is the key here. A thorough history and slit lamp exam is essential. With regards to the RCTs, “complicated” corneal abrasions that were excluded included: greater than 36 hours since injury; contact lens wearer; herpes; unable to follow up at 48 hours. It would be reasonable to be cautious in these patients, although there is no evidence that using topical anesthetics in these groups is harmful.

Then I talk to my patients and let them decide.

I don’t require follow up with an ophthalmologist, BUT I tell all my patients that they should be completely symptom free at 48 hours and if they aren’t, they need to come back to the ED for a reassessment.

Updates

Since I first published this, an excellent review of the topic has been published by some very smart people (Anand Swaminathan @EMSwami, Ken Milne @TheSGEM, Karalynn Otterness, and Salim Rezaie @srrezaie.)

Swaminathan A, Otterness K, Milne K, Rezaie S. The Safety of Topical Anesthetics in the Treatment of Corneal Abrasions: A Review. The Journal of emergency medicine. 49(5):810-5. 2015. PMID: 26281814

They found the same papers I did (thankfully) and conclude:

When dilute topical anesthetics are used appropriately and for a short duration, no adverse effects have been demonstrated, and potent pain control is attained. Although data are somewhat limited, on the basis of the available research, it is reasonable to prescribe a short course of a dilute topical anesthetic to reliable patients with simple corneal abrasions who have adequate followup.

I interviewed Salim Rezaie about this paper for EMCases Journal Jam. You can hear his thoughts on the topic here.


July 2017:

Waldman N, Winrow B, Densie I. An Observational Study to Determine Whether Routinely Sending Patients Home With a 24-Hour Supply of Topical Tetracaine From the Emergency Department for Simple Corneal Abrasion Pain Is Potentially Safe. Annals of emergency medicine. 2017. PMID: 28483289

This is a retrospective study in an emergency department that changed it’s policy to allow emergency physicians to prescribe topical 1% tetracaine drop every 30 minutes as needed for 24 hours in patients with corneal abrasions. Here, they retrospectively look at 1576 patients with corneal abrasions, 532 of which were classified as simple and 1044 were non-simple. Tetracaine was prescribed for 459 of these patients (after the policy change) and there were zero serious complications (upper bound of 95% confidence interval is 0.8%). 1 patient in the standard care versus 4 in the tetracaine group required reassessment with the ophthalmologist, although none with significant issues. There were a handful of patients given tetracaine who were ultimately diagnosed with something other than a corneal abrasion, such as herpetic keratitis or recurrent corneal erosions, which emphasizes the importance of a through history and examination, as well as the need to limit topical anesthetic use to a short course so as to not mask important symptoms.

Bottom line: It is becoming more and more clear that topical anesthetics are safe and effective at managing pain from corneal abrasions.


Other FOAMed Resources:

EMLyceum Eye Emergencies Answers

The SGEM#83: In Your Eyes (Topical Tetracaine for Corneal Abrasions)

R.E.B.E.L. EM Topical Anesthetic Use on Corneal Abrasions

SOCMOB Should we use tetracaine for corneal abrasions? Calgary EM Journal Club

Author: Justin Morgenstern

Community emerg doc, FOAM enthusiast, evidence junkie “One special advantage of the skeptical attitude of mind is that a man is never vexed to find that after all he has been in the wrong.” - William Osler

Leave a Comment

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s