Patients with corneal abrasions typically come to the emergency department for eye pain. Most physicians treat these with topical antibiotics, oral analgesia, and for those who are lucky enough 48 – 72 hour follow up with ophthalmology. Oral analgesia does a poor job of controlling these patients pain. Tetracaine is an esterase type anesthetic with a onset of action of 10 – 20 seconds and a duration of action of 10 – 15 minutes. Use of topical anesthetics are very effective at reducing pain, but there use is discouraged secondary to poor wound healing of the corneal epithelium. So what is the evidence for topical anesthetic use on corneal abrasions?
Where does the evidence for NO topical anesthetic use on corneal abrasions come from?
[table id=22 /]
The evidence for the toxic effects of topical anesthetics comes from case reports, case series, and animal studies. The case reports and series are listed above, and in all but one of the cases the patients were abusing topical anesthetics for weeks to months and/or concentrations higher than that typically used today. So the statements that topical anesthetics have toxic effects to the cornea and decrease or inhibit corneal reepithelialization come from patients abusing these medications and not using them for short periods of time.
Two animal studies [cite source=”pubmed”]1399407[/cite] and [cite source=”pubmed”]2409803[/cite] were examining toxicity of topical anesthetics. Topical anesthetics were being used at increasing concentrations until corneal epithelial damage was seen. Both studies were from the corneas of rabbits who have a more sensitive cornea and a reduced blinking rate when compared to humans, therefore it is hard to draw generalizations to humans.
What trials have evaluated the use of topical anesthetics on corneal abrasions?
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Conclusion: Topical anesthetics did a better job of controlling pain and in all but one of the studies no statistical difference in cornea epithelial healing at 72 hours.
What is the most recent trial to evaluate topical anesthetic use on corneal abrasions? [cite source=”pubmed”]24730399[/cite]
What they did:
- Prospective, double-blind, randomized trial of a convenience sample of 116 patients with uncomplicated corneal abrasions
- 1% tetracaine vs saline q30 minutes prn pain for 24 hours
- Largest RCT evaluating safety of topical anesthetics with uncomplicated corneal abrasions
- > 36 hours after initial injury
- < 18 years of age
- Wear contact lenses
- Injury to both eyes
- Grossly contaminated foreign body in eye
- Current herpes keratitis
- Allergy to tetracaine
- Injury requiring urgent optho evaluation
- Unable to make follow up at 48 hours
Main Safety Outcomes:
- Complications specifically attributed to topical anesthetic defined as:
- Delayed healing
- Enlarged abrasion
- Recurrent corneal ulceration
- Toxic keratitis
- surface keratopathy
- Corneal stromal infiltration
- Candida and bacterial keratitis
- Persistent fluorescein uptake at 48 hours for corneal evaluation
- 1 week and 1 month telephone interviews
- Every patient had at least one follow up evaluation
- Pain control with a 100-mm visual analog scale (VAS)
- Overall effectiveness with a numeric rating scale (NRS) of 0 – 10
- No complications attributed to topical anesthetic (CI of 0 – 6.1%), but this is a wide CI
- No statistically significant difference in corneal healing at 48 hours (23.9% vs 21.3% with p value of 0.761)
- Retained rust ring in 23 patients: tetracaine 22.0% vs saline 17.5% (p value = 0.544)
- Fluorescein uptake at 48 hours: tetracaine 23.9% vs saline 21.3% (p value = 0.761)
- No persistent symptoms at 48 hours (21.7% vs 21.3% with p value of 0.957)
- No difference in VAS pain scores at any time between groups
- Patients rated tetracaine having a better overall effectiveness on the NRS (7.7 vs 3.9)
- Excluded penetrating eye injuries, large or complicated corneal abrasions, and injuries causing a significant disruption of vision
- Some patients discovered when using the tetracaine drops they experienced burning similar to the tetracaine they were treated with in the ED which may have unblinded the patient and researcher
- Patient compliance with administering the tetracaine or saline was not recorded
- The study was under powered to detect a difference in the efficacy between the two groups
- There was poor follow up at 48 hours: Tetracaine group 69.0% vs Saline Group 64%
Conclusion: Topical tetracaine used for 24 hours was safe, patients felt they had a significantly higher overall effectiveness with tetracaine, but no significant difference in the VAS pain score.
There was a commentary to this study [cite source=”pubmed”]24730412[/cite] in which the author states: “Many common practices are driven by dogma, untested conventional wisdom, and opinions of both actual and self-promoted experts. Working with residents and students on a day-to-day basis is often the only thing that slows down busy clinicians long enough to consider the lack of evidence supporting many common practices.” He goes on to say that “ED physicians have been taught that topical anesthetic use is associated with poor healing, but this teaching is grounded in laboratory-based studies and case reports that describe prolonged, unsupervised use (or abuse) of topical anesthetics.” He finishes up by saying, “Whether or not to start using tetracaine routinely in the treatment of simple corneal abrasions remains up to the reader.”
How Your Pharmacist can Make a 1:10 (0.05%) Dilution From 0.5% Anesthetic
The inpatient pharmacy team should label the bottle with the following instructions for the patient:
Proparacaine 0.05% Ophthalmic
1 – 2 drops in affected eye q30 min prn pain
Disp: 2 – 3 mL
Lot#: Date of Disp:
**Not to exceed 24 – 48 hours of use
Take Home Message
To date the only evidence that topical anesthetics in uncomplicated corneal abrasions causing more harm come from experimental animal studies, case reports, and case series. Based on available evidence, it is most likely reasonable to send patients home with dilute topical anesthetics for a period of no more than 24 – 48 hours without patients having complications, but larger studies will need to occur before this recommendation is officially made.
More References on This Topic Since Initial Publication of This Post:
Waldman N et al. 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. Ann Emerg Med 2017; S0196 – 0644(17): 30195 – 6. PMID: 28483289
For More on This Topic Checkout:
- Ken Milne over at The SGEM: Episode #83 – In Your Eyes (Topical Tetracaine for Corneal Abrasions)
- Swaminathan A et al. The Safety of Topical Anesthetics in the Treatment of Corneal Abrasions: A Review. J Emerg Med 2015 [epub ahead of print] PMID: 26281814
- Puls HA et al. Safety and Effectiveness of Topical Anesthetics in Corneal Abrasions: Systematic Review and Meta-Analysis. J Emerg Med 2015 [epub ahead of print]
- The SGEM: Episode #145 – Topical Anesthetics for ED Patients with Corneal Abrasions