Standing on the corner, minding my own business in the ER

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

eyedrop

Hi all,

This month’s Calgary EM Journal Club had a fantastic turnout with almost 40 attendees, 25% of which were staff EM docs.  It also marked the first time we saw a heated, debate style showdown at the end from residents advocating for and against the use of topical tetracaine in treatment of corneal abrasions.  Two articles were reviewed, one by Ball et al. from CJEM 2010, and another by Waldman et al. from Academic Emerg Med 2014.  For previous journal club reviews, check out the journal club page.

The traditional dogma prohibiting use of topical tetracaine for treatment of corneal abrasions has been challenged in the past few years, gaining steam with the recent publication of Waldman’s article in April, 2014.  Textbooks tell us that topical tetracaine is toxic to corneas, and will result in corneal thinning, ulcers, keratitis and other ocular complications.  However, this is based primarily on animal, case report and case series data.  Fortunately, my friends Salim Rezzaie of Rebelem.com and Ken Milne of TheSGEM.com have posted about this dogma already, and I encourage you to check out their reviews, as well as Ken’s podcast over at TheSGEM.

The complete critical appraisal of both articles is available if you scroll down, however we’ll get to the bottom line right away as it is slightly different than what some others in the FOAM world are saying.

Clinical Bottom Line:

Given the current evidence, few physicians would universally provide topical tetracaine for the treatment of corneal abrasions, although some would consider it on a case-by-case basis until new data is available.

Prior to the evening’s discussion 9/38 journal club attendees would consider short-term topical anesthetics for corneal abrasions with 16/38 attendees considering this after discussion.

Cornealabrasion

As the main concern of the therapy is with respect to safety with potentially vision-threatening complications, a (0-6.1%) confidence interval was thought to be not yet ready to conclusively prove safety.  In order to prove safety, we are probably going to need somewhere in the realm of  1000 patients with corneal abrasions, and I think we have just over 100 right now in the EM literature. The photorefractive keratectomy (PRK) literature from the ophtho world can’t be grouped with the ED corneal abrasions because these are sterile, surgical incisions.

Furthermore, polling the ophthalmology consultant group, there is essentially no support of this treatment strategy, citing local anesthetic’s inhibition of corneal healing.

This will be the most important determinant of tetracaine use in your local center.  Will your ophtho colleagues support you? Will they support you in the case of a complication?

Below are full summaries of each article.

 

Article #1

Acad Emerg Med. 2014 Apr;21(4):374-82. doi: 10.1111/acem.12346.

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.

Waldman N1Densie IK, Herbison P. 

METHODS/SETTING/DESIGN

  • Double blinded randomized controlled trial from 2011 to 2012.
  • Study population: 116 patients with simple acute corneal abrasions presenting to a tertiary care Emergency Department in New Zealand
    • This size was a convenience sample with a post hoc 95% confidence interval for 0 complications of (0-6.1%)

INCLUSION CRITERIA

  • Simple, uncomplicated corneal abrasion from mechanical trauma, UV keratitis or foreign body.

EXCLUSION CRITERIA

  • Patient characteristics: age < 18, previous eye surgery, cataracts, deaf, unable to give informed consent, were unable to follow-up in 48 hours, and contact lens users.
  • Presentation > 36 hours
  • Ocular infection, herpes keratitis, concurrent injury requiring urgent ophthalmologic evaluation*
  • Bilateral Abrasion
  • Grossly contaminated foreign body.

*Although what mandates urgent ophthalmologic evaluation was not explicitly defined, suggested examples include complicated corneal abrasions, change in visual acuity and large corneal abrasion.

INTERVENTION/CONTROL

  • 1:1 sealed envelope randomization to either intervention or control:
  • Control envelope: 3x 1000mg acetaminophen tablets every 6 hours, 1% preservative chloramphenicol + 5cc saline eye drop placebo.
  • Intervention envelope: 3x 1000mg acetaminophen tablets every 6 hours, 1% preservative chloramphenicol + 5cc preservative-free 1%(undiluted) tetracaine.

OUTCOMES

Outcome measure(s):

Primary

Complication rate, as defined by any of: delayed healing, enlarged abrasion, corneal ulceration, toxic keratitis, surface keratopathy, corneal stromal infiltrates, infectious keratitis, uveitis and corneal infiltrates. This was assessed by combination routine 48 hour follow-up ED assessment/telephone interviews, and discretionary ophthalmologic follow-up.

Secondary

Pain scores on a 100mm visual analog scale.

Patient ratings of treatment effectiveness on a numeric rating scale during telephone follow-up.

RESULTS

– PRIMARY OUTCOME

  • There was no statistically significant difference in complication rates between treatment and control groups. No patients had any significant objective complications requiring changes in management.
  • These complications at 48 hours included persistent reuptake (23.9% v 21.3%) and persistent symptoms (21.7% v 21.35.) Of these patients, 5 required reassessment by ophthalmology but none required any additional treatment.

– SECONDARY OUTCOME

  • There was no clinically significant difference in pain scores at any time during the 48 hour treatment period, however there was a significantly higher mean followup NRS of tetracaine’s effectiveness. (7.7 v 3.8; p<0.0005.)

STUDY CONCLUSION

  • Topical 1% tetracaine is a safe and effective symptomatic treatment for acute, uncomplicated corneal abrasions.

 

Article #2

CJEM. 2010 Sep;12(5):389-96.

Dilute proparacaine for the management of acute corneal injuries in the emergency department.

Ball IM1Seabrook JDesai N, Allen L, Anderson S.

PMID:20880433

METHODS/SETTING/DESIGN

  • Double blinded randomized placebo-controlled trial.
  • 2 tertiary level care EDs in London, Ont.
  • 33 patients
  • Powered to detect with 80% power a 2cm difference in a 10cm visual analog pain scale.

INCLUSION CRITERIA

  • Adults with corneal injuries.

EXCLUSION CRITERIA

  • Inability to consent
  • Allergy to medication
  • Inability to followup
  • Previous eye injury or pathology

INTERVENTION/CONTROL

  • 1:1 randomization to topical fluoroquinolone, pain log, acetaminophen+codeine, and:
  • Intervention: topical proparacaine to 0.05%
  • Control: topical saline drops matched by colour and smell.

OUTCOMES

Outcome measure(s):

Primary

Difference in pain immediately before and 5 minutes after drop administration. Pain recorded on 2 separate 10cm visual analog scales. Pain log handed in at 5 days.

Secondary

Self-reported patient satisfaction on a 10cm visual analog scale.

Complications as assessed by a single ophthalmologist at 1,3, and 5 days, defined as:

  • Delayed wound by fluorescein
  • Increased corneal thickness
  • Corneal opacification
  • New corneal epithelial defects
  • Any other ocular pathology that could be related to the injury or medication

RESULTS

– PRIMARY OUTCOME

  • There was a significant decrease in pain in the intervention group. Mean reduction was 3.9 in the intervention group, and 0.6 in the control (p=0.007)

– SECONDARY OUTCOME

  • The intervention group had an improvement in patient satisfaction scores of 8 compared to 2.6 (p=0.027).
  • There were no complications in either of the 2 groups.

STUDY CONCLUSION

  • Topical diluted 0.05% proparacaine reduces pain due to corneal injuries and likely does not cause complications.

 

Thanks to Geoff Lampard (PGY4), Michael Szava-Kovats (PGY4) and Shawn Dowling for this month’s journal club. For more U of C Journal Club reviews, click here

Chris Bond

@scomobem

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