Treatment of Corneal Abrasions With Topical Tetracaine

Corneal abrasion (CA) is one of the most common eye injuries, accounting for 10% of eye-related emergency visits.1 A 1985 survey showed that around 3% of all visits to US general practitioners were for corneal abrasions. In addition, in 2008, approximately 27,450 work-related eye injuries and illnesses occurred that caused missed time from work.1Due to the large number of nerve endings even small corneal injuries can produce significant pain. The discomfort is typically most pronounced in the first 24-48 hours, and in many cases showed a loss in time at work and disruption of daily activities. The current standard of care in the emergency department includes topical analgesia and antibiotics with a change to oral analgesics upon discharge. Despite the ineffectiveness of oral analgesics in treating CA pain, most physicians do not prescribe topical analgesics based on standard medical teaching. This teaching is extrapolated from data from case reports and animal studies reporting complications associated with long-term use; including addiction, infection, ulceration, and increased healing time. Previous studies have also rejected topical analgesia citing equivocal effectiveness and inconclusive safety data. However, all of the early human case reports described patients who used topical anesthetics inappropriately-either far too frequently, for too prolonged a treatment period, or with too concentrated an anesthetic. Contrary to the medical cannon, studies have now begun show the effectiveness of topical anesthetics in reducing pain, and safe application when given at low doses and when given in quantities lasting only 24-48 hours. A recent prospective, randomized trial, published in Academic Emergency Medicine, observed the efficacy and safety of tetracaine compared to normal saline in 116 patients presenting with uncomplicated CA. The intervention was either undiluted topical tetracaine hydrochloride 1% or saline, applied up to every 30 minutes for 24 hours. The study showed topical tetracaine used for 24 hours was safe, revealing no difference in complications between the two groups, with all individuals attaining full healing within 1 month. Additionally, median visual analog scale (VAS) pain scores were lower in the tetracaine group at all study time points after presentation, however statistical significance was not observed. Furthermore, patient surveys on overall effectiveness revealed that patients perceived tetracaine to be significantly more effective than saline. In fact, several researchers now recommend that the short-term use of tetracaine eye drops for 24 hours for pain relief from simple corneal abrasions should become routine practice. Nevertheless both skeptics and supporters agree that more research is needed in order to appropriately establish topical analgesics as a the standard of care. The importance of conducting research in the management of CA is underscored by the significant impact topical analgesics may provide in reliving patients pain compared to standard treatment. The study's aim is to further investigate the role of tetracaine in the outpatient management of CA utilizing models already established to ensure safety. This study will employ a prospective, double blind, randomized control model to compare undiluted 1% tetracaine hydrochloride to normal saline in patients presenting to the ED with uncomplicated corneal abrasions. Tetracaine will be supplied in three plastic prefilled, commercially available vials, each containing 0.5 mL of preservative-free, undiluted 1% tetracaine hydrochloride (a total of 1.5 mL or approximately 50 drops will be provide to avoid overuse). Saline will also be supplied in three plastic prefilled, commercially available vials, plastic bullets. Follow up visits or calls will be provide at 48 hour to reevaluate symptoms an asses the patients perceived pain using VAS provided in participant introduction packet during the informed consent process.

STUDY PROCEDURES

1. Study visits and parameters to be measured Patients will be assessed using a VAS upon follow up at 48 hours. Patients will also be evaluated for complications either by phone or at a follow-up visit, which is at the participants discretion. All patients will be encouraged to follow up with ophthalmology as-per standard protocol.
2. Drugs to be used (dose, method, schedule of administration, dose modifications, toxicities), include Toxicity Grading Scale (if applicable) Tetracaine will be supplied in three plastic prefilled, commercially available vials, each containing 0.5 mL of preservative-free, undiluted 1% tetracaine hydrochloride (a total of 1.5 mL or approximately 50 drops will be provide to avoid overuse). Patient will be instructed to use no more than 1-2 drops in the affected eye every 30 minutes while awake for 24-48 hours

STATISTICAL ANALYSIS

1. List of variables and their definition Variables will include perceived pain using a VAS, and overall perceived effectiveness of solution provided.
2. Outcome measures,endpoints The outcome of interest is weather-or-not tetracaine is superior to placebo in controlling pain caused by CA
3. Type of analysis A two sample T-test will be used comparing the average pain scale between the tetracaine and placebo group
4. Sample size of 100-200 patients is expected