Topical Anesthetics in Corneal Abrasions

Background

Corneal abrasions account for approximately 10% of eye-related visits to the Emergency Department (ED). The cornea is a highly innervated structure and, thus, remarkably sensitive, making this condition a notoriously painful one. We have all witnessed the almost magical analgesia achieved with application of topical anesthetics when evaluating these patients. Unfortunately, we limit the use of this effective pain management modality to the ED because of the seemingly prohibitive dangers of prolonged use of these agents. The proposed risks include delayed healing secondary to inhibition of mitosis and direct toxicity to the corneal epithelium leading to increased corneal thickness, opacification, stromal infiltration, and epithelial defects. There is also a fear that decreased corneal sensation is actually undesirable due to the risk of progression to ulceration without the patient noticing. The evidence for these toxic and untoward effects that has served as the basis for the pervasive teaching that topical anesthetics should never be used for the outpatient management of corneal abrasions and has stripped us and our patients of this potentially effective (and opiate-sparing) modality is derived from arguably weak case reports, case series and animal studies. There is mounting evidence from both ophthalmology and emergency medicine literature that demonstrates the efficacy and safety of this pain management modality.

Primary Results

• 2 studies involving a total of 149 patients who presented to ED with corneal abrasions revealed that short term use of topical anesthetic (either proparacaine or tetracaine) was safe and effective in achieving analgesia
  • Ball et al. randomized 33 patients to receive either 0.05% proparacaine or placebo drops (2-4 drops as needed for 7 days) and found markedly better analgesia at 5 minutes as assessed on a 10-cm visual analogue scale with no complications or signs of delayed healing in either group
  • Waldman et al. randomized 116 patients to receive either 1.0% tetracaine or placebo (1 drop every 30 min for 24 hours) and found no difference in corneal healing at 48 hours and no difference in VAS pain scores
• 4 studies from ophthalmology literature evaluating usefulness of topical anesthetics for pain management after PRK (141 patients in total) also suggest that the short term use of topical anesthetics is effective and safe
  • Verma et al. (1995) randomized 44 patients to receive 1.0% tetracaine or placebo (1 drop every 30 min while awake for 24 hours) and found no difference in rate of epithelial closure with complete closure at 72 hours for all patients in both groups and more effective analgesia in the tetracaine group as assessed by the Visual Analog Pain Chart (reduction of pain from 10 to 2.5 vs 10 to 6.5) and by patient report 1 week after PRK (39% vs 85% reported post-PRK period as “painful”)
  • Verma et al. (1997) randomized 38 patients to receive either 0.75% bupivacaine vs 1.0% tetracaine (1 drop every 30 min while awake for 24 hours) and found slightly better analgesia with tetracaine and, again, full epithelial closure in both groups at 72 hours
  • Shahinian et al. evaluated 34 patients after PRK who self-administered either topical 0.05% proparacaine or placebo for 1 week after PRK and found significant more and sustained pain relief in the proparacaine group with no difference in number of days needed to reach complete epithelial healing between groups
  • Brilakis and Deutsch provided 49 patients with 10 drops of 0.5% tetracaine after PRK and found complete epithelial healing in all patients at 3 days with effective analgesia

Critical Findings

• There were no adverse events identified on the ED-based and PRK studies from topical anesthetic use
• Three of the studies reviewed demonstrated adequate epithelial healing at 72 hours and one study found adequate healing at 24 hours
• Three studies that compared topical anesthetic to placebo revealed efficacy benefit (efficacy equivocal on Waldman study)

Strengths

• Prospective, randomized-controlled studies reviewed that addressed discrete question and common problem with clinically relevant outcomes
• Search strategy was exhaustive
• Studies reviewed were of high methodological quality
• Assessment of studies reproducible

Limitations

• Unpublished research and research abstracts not considered in systematic review
• Quality assessment instruments not employed (i.e. PRISMA)
• Highly heterogeneous studies analyzed (could not perform meta-analysis)
• PRK presumed to be functionally similar to corneal abrasion but not exactly representative of lesions and patients who present to ED
• Limited number of studies and patients analyzed prohibit reliable safety analysis

Author's Conclusions

“Limited available data suggests that the use of dilute topical ophthalmologic proparacaine or tetracaine for a short duration of time is effective, although their safety for outpatient use is inconclusive.”

Our Conclusions

The use of topical ophthalmologic anesthetics for pain management of simple corneal abrasions is effective and may be safe.

Potential Impact To Current Practice

Topical anesthetics could be a useful tool in managing pain from corneal abrasions in a select and reliable cohort of uncomplicated patients who are diagnosed with this condition in the ED and who have prompt (48-72 hr) follow-up.

Bottom Line

Topical anesthetics are effective in managing pain associated with corneal abrasions. The risk and safety concerns associated with the use of topical anesthetics is likely overstated but larger studies should be undertaken to assess safety before the widespread use of this pain management modality can be recommended.

Read More

The SGEM: Topical Anesthetics for ED Patients with Corneal Abrasions

REBEL EM: Topical Anesthetic Use on Corneal Abrasions