Tetracaine eye drop dulls corneal abrasion pain

Topical tetracaine appears to take the sting out of acute corneal abrasions, reducing opiate requirement without increasing complications, as shown in a study.

In a randomized controlled trial of 111 adult patients, median pain scores for the first 24 to 48 hours of treatment were 1 out of 10 with tetracaine versus 8 out of 10 with placebo (p<0.001). [Ann Emerg Med 2021;77:338-344]

Furthermore, patients given tetracaine ingested only a median of one hydrocodone tablet for breakthrough pain. This was significantly lower compared with the median of seven tablets among those on placebo. There were no serious adverse events.

The analysis included 56 patients on tetracaine and 55 on placebo, with baseline pain score of 7 in both arms. Patients in the active treatment arm reported applying the study drops more times (9 vs 5). However, there was no significant difference in the number of patients found to have a small residual corneal abrasion on their repeated slit-lamp examination (18 percent vs 11 percent, respectively).

“Uncomplicated corneal abrasions are commonly observed and treated in the emergency department. Even minor corneal abrasions can cause considerable pain as a result of the cornea’s vast innervation. Emergency physicians should aim to provide adequate analgesia in the safest manner possible,” according to the investigators.

“In our current study, to our knowledge the largest randomized controlled trial to date, we found topical tetracaine to be effective, and it appears safe for short-term use in treating corneal abrasions diagnosed in the ED. We found a 6.1-point reduction in the overall numerical rating scale pain score at 24 to 48 hours versus that in the placebo group,” they added.

The findings also suggest that short-term topical anaesthetic use for acute complicated corneal abrasions could reduce or eliminate opioid prescriptions. The investigators emphasized its weight, given that even a single opiate prescription for acute pain from the emergency department can lead to more prescriptions and then escalate to opioid use disorder.

“The United States is currently in the midst of an opioid crisis, with substantial increases in opioid use disorder, as well as fatal and nonfatal opiate overdoses, reported during the last few decades,” they noted.

One important limitation to the study was that it was not powered to establish safety for rare adverse events that could be associated with topical anaesthetic use. A much larger sample size would be needed to rule out such events, the investigators said. 

Nevertheless, they are positive that topical anaesthetics can be safely prescribed to patients with uncomplicated corneal abrasions for 24 hours. “As long as they are provided close ophthalmology follow-up and return precautions.”