corneal abrasion, anesthetic eye drops:
A moderate-sized corneal abrasion can be extremely annoying, obvious here by fluorescein dye staining. Symptoms usually subside spontaneously in 48-72 hours, but abrasions can be quite painful and annoying for the first day or so. Tetracaine anesthetic eye drops can be used safely at home for 24-48 hours. Relief of symptoms is immediate and complete, but lasts for only 30-60 minutes. Prior concerns about problems with patients using tetracaine drops have not been substantiated. Eye patches are no longer recommended. According to the Cochrane Database, an eye patch placed over a corneal abrasion does not improve or hasten healing, reduce pain, or lessen a foreign body sensation. Some pain relief can also be obtained with diclofenac NSAID eye drops (0.1%). Oral opioids are also recommended for pain control, but are often not provided by emergency physicians.
Figure
Traumatic corneal abrasions and superficial corneal foreign bodies are bread-and-butter cases for most emergency physicians. The diagnosis and treatment are generally easily handled in the ED, and the majority of patients are asymptomatic within 48 to 72 hours. Complications are rare. Topical anesthetic eye drops make manipulation of corneal abrasions and minor foreign bodies totally painless, but patients can be quite uncomfortable for the 36-72 hours after the pain relief dissipates, which usually occurs within an hour or two.
Because topical anesthetic drops make corneal manipulations totally painless, it makes sense that the same drops should be provided for outpatient pain relief. But anesthetic drops for home use have been prohibited for years by ophthalmologists, and their use is still frowned upon in much of the literature. This was raised decades ago based on concerns about overuse and complications that can develop in the anesthetized eye. True data on adverse effects from short-term use of low-concentration drops are lacking (J Emerg Med. 2015;49[5]:816), yet prohibitions remain despite a few well-designed studies that have essentially invalidated the concerns. Many emergency physicians nonetheless remain reluctant to offer safe and effective relief of pain with anesthetic eye drops following ED discharge.
Short-Term Topical Tetracaine is Highly Efficacious for the Treatment of Pain Caused by Corneal Abrasions: A Double-Blind Randomized Clinical Trial
Shipman S, Painter K, et al.
Ann Emerg Med.
2020;S0196-0644(20):30739
http://bit.ly/3st0Pni
The authors evaluated the short-term effect of take-home topical tetracaine eye drops v. saline placebo in 111 patients who received ED treatment for uncomplicated corneal abrasions. They noted that topical anesthetics for the outpatient treatment of corneal abrasions are discouraged by most emergency medicine textbooks because of concerns over safety. Case reports of abuse and misuse as well as animal studies have suggested that long-term use of topical anesthetics may lead to rare complications, so their use has long been discouraged.
The authors, however, undertook this study based on demonstration of the safety and efficacy of topical anesthetics for post-operative pain from keratectomy and no delayed healing after a short course of anesthetic drops in outpatients. This is one of a few similar studies that have demonstrated safe and effective analgesia from outpatient topical anesthetics. (Acad Emerg Med. 2014;21[4]:374.)
The anesthetic drops were prescribed for 24 hours, not only for pain relief but also to decrease the use of systemic opioids for pain control. Subjects were randomly chosen to receive an antibiotic ophthalmic solution (polymyxin B/trimethoprim) to be used every four hours and either 0.5% tetracaine drops or saline, one drop every 30 minutes as needed for pain for a maximum of 24 hours. The physicians and patients were blinded to the content of the drops. Participants also received a prescription for hydrocodone/acetaminophen (7.5/325 mg), and were told to use one or two tablets every six hours as needed for breakthrough pain.
Patients were excluded if they used contact lenses, had prior corneal surgery, presented more than 36 hours after injury, had a grossly contaminated foreign body, or required urgent ophthalmologic evaluation for other reasons. Patients were reassessed at 24 to 48 hours in the ED by slit lamp to assess the degree of healing and any complications. The initial endpoints of the study were pain relief and the amount of hydrocodone used for breakthrough pain. Delayed complications were documented by ophthalmology follow-up or a phone call.
The overall pain score after the use of the study drops was significantly lower in the tetracaine group v. the placebo group, with a respective pain score of 1 v. 8. The residual size of the corneal abrasion did not differ between the two groups at follow-up. Only about 20 percent of patients in each group attended the one-week follow-up with a study ophthalmologist, probably due to the relatively rapid healing period. Patients given tetracaine also used fewer opioids for breakthrough pain. Interestingly, those receiving tetracaine used on average only one hydrocodone tablet compared with seven tablets by those receiving placebo. The authors concluded that short-term topical tetracaine eye drops provided safe and efficacious analgesia for an acute uncomplicated corneal abrasion, and that use of the drops was associated with significantly less hydrocodone use compared with placebo.
Topical Tetracaine Used for 24 Hours is Safe and Rated Highly Effective by Patients for the Treatment of Pain Caused by Corneal Abrasion: A Double-Blind Randomized Clinical Trial
Waldman N, Densie IK, et al.
Acad Emerg Med.
2014;21(4):374
These authors randomized 122 patients with a traumatic corneal abrasion or a corneal abrasion caused by the removal of a corneal foreign body to receive outpatient topical anesthetic eye drops v. saline. Following ED evaluation, patients were discharged with instructions to take two acetaminophen tablets (500 mg) every four hours and to instill saline or 1% tetracaine anesthetic drops into the involved eye as frequently as every 30 minutes while awake. Chloramphenicol antibiotic eye ointment was also dispensed to all patients.
Patients were reassessed at 48 hours in the ED for any complications and overall complaints. A slit lamp evaluation with fluorescein staining was performed, and a follow-up phone call occurred within one week. The investigators specifically evaluated patients for delayed healing, recurrent corneal ulcerations, toxic keratitis, fungal or bacterial infections, uveitis, hypopyon, or corneal infiltrates. No complications specifically attributed to the topical anesthetic were identified, and no difference was seen in healing rates. Curiously, the authors were unable to show any clinically significant difference in pain scores between the tetracaine and saline groups, but the anesthetic was rated as much more effective than placebo.
The authors stated that laboratory experiments on animals have demonstrated some direct toxic effects to the cornea from topical anesthetics, but similar results have not been shown in humans. Most complications have been attributed to repeated use of high-concentration drops. These authors concluded that short-term use of tetracaine anesthetic drops to relieve pain from corneal abrasions is safe and effective, and that use of tetracaine eye drops for 24 hours should become routine practice.
Comment: A number of topical anesthetics are available to relieve pain of the cornea. These include tetracaine, proparacaine, lidocaine, and cocaine. Tetracaine and proparacaine are most commonly used. Their concentrations are relatively weak, and tetracaine is commonly used in a 0.5% or 1% concentration. A single drop in the eye will produce complete corneal anesthesia within a few seconds and will last for 30-45 minutes. Some minor transient burning can be seen with tetracaine drops. Anesthesia is immediate and quite profound, and can make surgery of the cornea totally painless.
Figure:
Tetracaine eye drops (0.5-1%) can be self-administered at home every 45-60 minutes for 24-48 hours to control discomfort from a corneal abrasion. The bottle of tetracaine used in the ED can be given to the patient to take home with proper instructions. The patient should be cautioned to avoid rubbing or massaging the anesthetized eye. Outpatient anesthetic drops should only be used by experienced clinicians who have evaluated the eye with a slit lamp and fluorescein dye, and follow-up is mandatory in 48-72 hours. A fast-track evaluation solely by an NP, PA, or resident who uses outpatient anesthetic drops without supervision is asking for trouble.
The discomfort of a corneal abrasion can be rather annoying, and physicians should be willing to provide some sort of pain relief. A few oral opioids should be routinely prescribed, but they are not often used by many physicians. The medical literature reports complications from the prolonged use of high concentrations of topical anesthetics, but these are usually after repeated use for many weeks or months, often on an hourly basis, and certainly not following the use that would be prescribed from the ED.
The use of an eye patch for corneal abrasions used to be routine, but is no longer recommended. A patch can provide some pain relief for large abrasions, but the literature for their value is inconsistent. (Cochrane Database Syst Rev. 2016;7[7]:CD004764.) Some clinicians use cycloplegics (dilating eye drops) to inhibit pupil constriction response to light, a reflex that causes discomfort. Those who are particularly photophobic can be treated with 48 hours of cyclopentolate (0.5%-1%) drops twice a day. This muscarinic antagonist will cause a markedly dilated pupil for up to 36 hours and make reading or working on a computer difficult. Use varies among physicians.
Topical tetracaine can be dispensed in a number of ways. It seems excessive to write a prescription when one has used just a small amount from a bottle of tetracaine in the ED. I have had patients steal the bottle that was used for their procedure, but I see no reason not to give it to them to take home after emptying out about half of the bottle. Patients can be instructed to use it as needed, generally every 30 to 60 minutes, and dispensing this small sample will avoid prolonged use. Patients with glaucoma can safely be given topical anesthetics because they actually reduce intraocular pressure.
One possible complication of anesthetic eye drops is patient-induced trauma that can occur when the eye is numb. Make sure you warn the patient that he will have no feeling in the eye, so rubbing it, particularly if there is a foreign body, can produce damage without any sensation. I see no reason to avoid short-term use, up to 48 hours, of topical anesthetic drops to relieve the annoying discomfort that occurs with a corneal abrasion. Complete relief of symptoms is immediate, albeit short-lived.
I don’t think most ophthalmologists would have strong objections to the short-term outpatient use of topical anesthetic drops for simple corneal abrasions. The key is that the diagnosis in the ED has to be correct, and I am sure many ophthalmologists providing follow-up care have seen an EP make the wrong diagnosis. Topicals should not be considered unless the physician is experienced and skilled in using a slit lamp and fluorescein. An unsupervised PA, NP, or resident should not handle these cases alone, but often such patients are sent to the fast track. When seen by an inexperienced clinician, an ED-diagnosed abrasion can actually be a laceration, and a superficial foreign body can penetrate the globe, so be careful. A good review of this topic can be found in the Journal of Emergency Medicine (2015;49[5]:810).
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Dr. Robertsis a professor of emergency medicine and toxicology at the Drexel University College of Medicine in Philadelphia. Read his past columns athttp://bit.ly/EMN-InFocus.