Posts tagged #corneal abrasion

Tetracaine

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Written by: Jonathan Hung, MD, (NUEM PGY-3) Edited by: Matt Klein, MD (NUEM ‘18) Expert commentary by: Dr. Glaucomflecken


Introduction

Corneal abrasions are a commonly encountered eye-related presentation in the emergency department (ED) [1]. Patients will often have a significant amount of pain from even minor abrasions. Topical anesthetics such as tetracaine have been found to be effective in treating the pain and are now routinely used in the ED [2]. However, the use of topical anesthetics for corneal abrasions in the outpatient setting is controversial due to concerns over safety and delayed healing. These traditional concerns over the prolonged use of topical anesthetics are based on early animal studies and case reports in humans [3]. The current literature suggests that topical anesthetics are, in fact, safe and effective if given as a short course with appropriate follow up, but further studies with larger patient populations are needed to support these findings [4]. A recent study published in Annals of Emergency Medicine is one of the largest studies to date that examines the safety of discharging patients home from the ED with a short supply of tetracaine for corneal abrasions.

Study

Waldman N, Winrow B, Densie I, 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. 

Study Design

The study design was a single-center, retrospective cohort study with ethics approval given by the Human Ethics Committee at the University of Otago. 

Population

The study was performed at the ED of Southland Hospital, Invercargill, New Zealand. A computer search of the hospital’s ED information system was conducted looking for all eye-related diagnoses and charts were reviewed between February 1, 2014 to October 31, 2015. Patients were initially selected if they were seen in the ED with an injury or illness involving the cornea. 

Intervention protocol

Patients with simple corneal abrasions were discharged home with undiluted 1% tetracaine hydrochloride in addition to the standard treatment of acetaminophen and chloramphenicol eye ointment. Instructions were given to place tetracaine in the eye as often as every 30 minute over the first 24 hours.  

Outcome Measures

  • ED rechecks 

  • Persistent fluorescein uptake

  • Ophthalmology clinic referrals

  • Complications

Results

There was a total of 1,576 ED presentations of corneal abrasions of which 532 were simple corneal abrasions (SCA) and 1,044 were defined as nonsimple corneal abrasions (NSCA). Tetracaine was given to 57% (303) of SCA patients and 14% (141) of NSCA patients. Overall, there were no serious complications or uncommon adverse events in either the SCA or NSCA group (0/459). The relative risk of patients with SCA receiving tetracaine and returning to the ED, having fluorescein uptake, or requiring a referral to ophthalmology was low compared to the standard treatment group. 

Interpretation

This study is one of the largest studies to examine the safety of outpatient tetracaine use in simple corneal abrasions. More importantly, it gives a robust conclusion similar to previous smaller studies in that there was no evidence that using topical tetracaine for a short duration caused harm. The strengths of this study include the large patient population and good patient follow-up. Furthermore, the physicians that administered tetracaine did not know that an observational study was planned, thus increasing the internal validity. However, the researchers were not blinded to the hypothesis which could have led to bias when collecting data. This was also a retrospective study and therefore due to the lack of randomization, those who received tetracaine may have differed from those who did not. Another limitation was that it was not known if all the patients administered the tetracaine as instructed after leaving the ED. Also, the diagnosis of simple corneal abrasion was limited to what the physician documented in the chart. The external validity is limited since this was a single-center study and about 71% of the patients were males. Overall, this study further strengthens the role of tetracaine in treating pain secondary to simple corneal abrasions and may gradually change practice patterns in the emergency department despite traditional teaching. 

Take Home Points

  • Topical tetracaine is effective in treating pain due to corneal abrasions

  • Patients with simple corneal abrasions can benefit from a short course of topical tetracaine to treat pain 

  • Topical tetracaine use over a 24-hour period is generally safe 

  • Emergency medicine physicians should consider incorporating topical tetracaine in their practice for treating SCAs 


Expert Commentary

This is an interesting observational study regarding the safety of prescribing a limited supply of topical tetracaine to patients who present to the emergency department with what the authors describe as “simple corneal abrasions.” It is well documented in the literature that long term use of topical anesthetics can lead to a variety of serious ophthalmic complications, including persistent epithelial defects, neurotrophic ulceration, secondary infectious keratitis, corneal scarring and perforation. However, many of these reports describe long term use of anesthetics ranging from 7 days to 6 months which have helped establish the long-held dogma that topical anesthetics are only appropriate for use during surgery or clinic examination. This study, as well as several smaller previous studies, has attempted to challenge that dogma in an effort to better treat the immense pain often associated with corneal abrasion.

The authors did a great job trying to distinguish between simple and non-simple corneal abrasions. This can be very difficult, even for an ophthalmologist. What may look like a simple corneal abrasion can easily turn out to be a different diagnosis altogether. Herpes simplex keratitis can present as a geographic ulcer, lighting up with fluorescein much like a corneal abrasion without the tell-tale sign of dendritic lesions to accompany it. Dry eye disease can result in confluent, punctate epithelial defects which can look like a corneal abrasion without the magnification afforded by a slit lamp. These conditions should not be treated with topical anesthetics and will only delay the patient in receiving appropriate care. Stating that topical anesthetics are safe for simple corneal abrasions assumes that the examiner is able to accurately diagnose a simple abrasion. In this study, several patients were misdiagnosed as simple abrasions and ultimately required follow up with ophthalmology. Patients who need to see ophthalmology for a non-simple abrasion may be less likely to follow up in a timely manner if they are given topical anesthetic that will effectively mask the pain. This can result in more extensive corneal scarring from a variety of diagnoses such as delayed rust ring removal or treatment of infectious keratitis.

The authors make a compelling point that a limited supply of tetracaine in a subset of corneal abrasions intended to last no more than 24 hours is safe with no significant difference in the number of ED rechecks, ophthalmology clinic referrals, persistent fluorescein uptake, or complications. If this is indeed true, is treating with topical anesthetic worth it? At best, you are providing a minimally-painful healing process which will be complete in 48-72 hours regardless of topical anesthetic use. At worst, you are masking pain of a potentially vision-threatening process that may have been misdiagnosed as a simple abrasion. I contend that setting patient expectations regarding pain (very severe for first 24 hours, then rapid improvement) and discussing more conservative comfort measures like icing and patching are sufficient.

Lastly, I want to discuss the treatment for simple and non-simple corneal abrasions. It is unclear whether or not the patients in this study were treated with topical antibiotics. It is possible that patients with simple corneal abrasions were sent home with a 24 hour supply of tetracaine and no topical antibiotics. Without an epithelial barrier, the underlying corneal stromal is prone to infection. Topical antibiotics act as a preventive measure and are particularly important if a patient is using topical anesthetic, which could mask the pain of infectious keratitis. Although not all sources agree, there is general consensus among ophthalmologists that all corneal abrasions require topical antibiotics at the time of diagnosis.

In conclusion, I agree that a 24 hour prescription of topical anesthetic in a simple corneal abrasion is likely safe. However, given the rapid healing time, consideration should be made to counseling patients on pain expectation and comfort measures in place of topical anesthetic. Lastly, prescribing more than a 1 day supply of topical anesthetic is unnecessary given the rapid improvement in pain after the first 24 hours


 

Dr. Glaucomflecken, MD

https://www.drgcomedy.com/

https://twitter.com/dglaucomflecken

http://gomerblog.com/author/glaucomflecken/

How To Cite This Post

[Peer-Reviewed, Web Publication] Hung J,  Klein M. (2019, July 8). Tetracaine. [NUEM Blog. Expert Commentary by Dr. Glaucomflecken]. Retrieved from http://www.nuemblog.com/blog/tetracaine.


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References

  1. Verma A, Khan FH. Corneal abrasion. MedscapeAvailable at: http://emedicine.medscape.com/article/1195402-overview. Accessed November 1, 2017.

  2. Waldman N, Densie IK, Herbison P. Topical tetracaine used for 24 hours is safe and rated highly effective by patients for the treatment of pain caused by corneal abrasions: a double-blind, randomized clinical trial. Acad Emerg Med 2014;21:374–82.

  3. Chang YS, Tseng SY, Tseng SH, et al. Cytotoxicity of lidocaine or bupivacaine on corneal endothelial cells in a rabbit model. Cornea 2006;25:590–6.

  4. Swaminathan A, Otterness K, Milne K, Rezaie S. The Safety of Topical Anesthetics in the Treatment of Corneal Abrasions: A Review. J Emerg Med. 2015;49(5):810-815. 

Posted on July 8, 2019 and filed under Ophthalmology.

Corneal Abrasions

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Written by: Julian Richardson, MD, MBA (NUEM PGY-2) Edited by: Andrew Moore, MD (NUEM ‘18) Expert commentary by: Brad Sobolewski, MD, MEd


A 40 yo construction worker comes to Emergency Department with a foreign body sensation in his left eye for two days. He states that he forgot to wear his eye protection while sanding a plank of wood the other day and felt like something has been scratching his eye ever since. Upon entering the room, his left eye is hyperemic and the patient appears to be in discomfort.

 

Approach to the painful red eye with foreign body sensation

The initial differential diagnosis to a painful red eye is broad and includes entities such as keratitis, corneal abrasions, corneal ulceration, acute angle glaucoma, iritis, chemical burn, scleritis, subconjunctival hemorrhage, and conjunctivitis. The patient’s history is particularly concerning for corneal abrasion, corneal ulceration, or globe rupture. A simple test to distinguish these diagnoses is the fluorescein exam.

 

Fluorescein exam

Fluorescein has been used in ophthalmology since the 1880s. This exam should be included for all patients where there is a suspicion of abrasion, foreign body, or infection. Fluorescein absorbs light in blue-wavelengths and emits energy in green wavelengths. It fluoresces in alkaline environments, for example Bowman’s membrane which is located below the corneal epithelium. It does not fluoresce in acidic environments such as the tear film over intact cornea.  Because of this, defects in the cornea increase fluorescein uptake and assist in locating corneal damage.

The eye should first be numbed usually with the use of a topical anesthetic drop, such as tetracaine. Next, take a fluorescein strip and place one drop of saline or local anesthetic to the strip. Place this strip inside the lower lid, remove, and ask the patient to blink. The key to a good exam is to produce a thin layer covering the surface of the eye. If too much is applied, the excess can easily be removed by asking the patient to blot their eye while closed with a tissue. The eye should then be examined using a Wood’s lamp, blue filter of a slit lamp, or penlight with a blue filter

Warning! this dye will permanently stain soft contact lenses and clothing. Be sure to remove any contacts and have plenty of gauze or other absorbant material available prior to instillation. Irrigating the excess dye out the eye after examination will help minimize staining the patient’s clothing.


Corneal Abrasion

 

Definition

  • Scratch to the epithelium that comprises the cornea and exposes the basement membrane. Patients generally complain of a foreign body sensation, pain, photophobia, and some vision loss. On physical exam, the clinician may find injected conjunctiva, and decreased visual acuity (if the defect is large or lies in the visual axis).

 Fluorescein Exam

  • Typically, abrasions are seen at the central part of the cornea due to limited protection of closure of the patient’s eyelids. The margins are sharp and linear in the first 24hrs. Circular defects suggests an embedded foreign body is present and may persist for greater than 48hrs. Foreign bodies can also produce vertical linear lesions and the upper lid should be lifter up to look for a foreign body under the eyelid

Management

  • Treatment with antibiotics have become the standard of care. Antibiotics are particularly indicated for abrasions caused by contacts (cover for pseudomonas), foreign bodies, or history of trauma with infectious or vegetative matter due to a higher risk of infection. Ophthalmic antibiotic therapy include: erythromycin ointment or sulfacetamide 10%, polymyxin/trimethoprim, ciprofloxacin, or ofloxacin drops (4 times a day for 3-5 days). Pain relief can be provided with oral or topical pain meds. Topical NSAIDs include .1% indomethacin, .03% flubiprofen, .5% ketorolac, 1% indomethacin, and .1% diclofenac.  If symptoms persist greater than 24 hours after treatment the patient should follow-up with a physician. If the abrasion has not healed in 3-4 days the patient should be evaluated by an ophthalmologist.

  

Corneal Ulceration

after ulceration.png
 

Definition

  • When a defect in the corneal epithelium becomes infected with bacteria or fungi it is defined as a corneal ulceration. This is a common complication of corneal abrasions and if left untreated can result in a corneal perforation.

Fluorescein Exam

  • Corneal staining with infiltrate or opacification around the lesion should raise suspicion for ulceration. Contact lens wearers raise the suspicion of a Pseudomonal infection. Many Pseudomonal organisms fluoresce when exposed to UV light and fluoresce prior to fluorescein application.

Management

  • Concern for ulceration requires an urgent ophthalmology consultation within 24hrs. Discharged patients should be treated with antibiotic drops or ointment.

Globe Rupture

Definition

  • Full thickness injury to the cornea, sclera, or both secondary to penetrating of blunt trauma.

Fluorescein Exam

  • Seidel test: instill a large amount of fluorescein onto eye and looking for small stream of fluorescent blue or green fluid leaking from the globe.

Management

  • Once suspected, avoid further examination or manipulation, make the patient NPO, and place an emergent ophthalmology consultation. These patients also require broad spectrum IV antibiotic coverage with a 3rd generation cephalosporin or aminoglycoside and vancomycin to prevent post-traumatic endophthalmitis.

In summary, all patients with eye pain, particularly with a foreign body sensation, warrant a fluorescein exam. A wealth of information can be gained by this simple test and will guide the management of the patient.


Expert Commentary

This is a very comprehensive review of a common complaint in the Emergency Department. You correctly identified that one must be careful to avoid instilling too much fluorescein so as to cause a false positive result. Though a drop of tetracaine or saline dilutes the fluorescein from the strip somewhat the quantity is hard to control at times – especially in noncompliant patients (like the children I usually examine in the Pediatric Emergency Department). Excess fluorescein can collect across the eye making identification of small abrasions challenging. If you put too much in rinse the eye and try again. It is also incredibly important to not sent the patient home with tetracaine drops, as too frequent use may lead to further corneal injury. The evidence is based on animal models and case series and is far from complete. Read more on this great R.E.B.E.L. EM post (link: http://rebelem.com/topical-anesthetic-use-corneal-abrasions/).

One of the main pitfalls to the use of fluorescein strips is the risk of actually causing an abrasion. The method noted in this article – placing the strip inside the lower lid margin and asking the patient to blink – can cause an abrasion if the edge of the strip touches the cornea. This is particularly challenging to do in children, since even with proper restraint the blink reflex and their tendency to recoil is high. Therefore I recommend doing one of the following:

  1. Hold the patient’s eyelids open. Drip the tetracaine or saline down the strip and allow it to drip into the eye, being careful to avoid touching the strip to the eye.

  2. Make a fluorescein dropper. This is well detailed in the Tricks of the Trade: Fluorescein application techniques for the eye form Academic Life in Emergency Medicine (link: https://www.aliem.com/2015/06/tricks-of-the-trade-fluorescein-eye/). The Angiocath dropper allows for better control of droplet size and makes it easier to instill fluorescein into the squinting eye without the risk of touching the cornea.

 

Brad Sobolewski, MD, MEd

Associate Professor, Assistant Director - Pediatric Residency Training Program

Division of Emergency Medicine

Cincinnati Children's Hospital Medical Center


How To Cite This Post

[Peer-Reviewed, Web Publication] Richardson J, Moore A. (2019, May 20). Corneal Abrasions [NUEM Blog. Expert Commentary by Sobolewski]. Retrieved from http://www.nuemblog.com/blog/corneal-abrasion


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References

  1. Images courtesy of http://www.tedmontgomery.com/the_eye/

  2. Marx, J. A., & Rosen, P. (2014). Rosen's emergency medicine: Concepts and clinical practice (8th ed.) Ch. 71. Opthamology. Philadelphia, PA: Elsevier/Saunders

  3. Yanoff, M., Duker, J. S., & Augsburger, J. J. (2009). Ophthalmology. Ch 4, Corneal anatomy, physiology, and wound healing. Edinburgh: Mosby Elsevier.

  4. Roberts, J. R., In Custalow, C. B., In Thomsen, T. W., & In Hedges, J. R. (2014). Roberts and Hedges' clinical procedures in emergency medicine. Ch 62. Opthalmologic procedures.

  5. Gardiner, M. F. Overview of eye injuries in the emergency department. Retrieved September 16, 2017, from https://www.uptodate.com/contents/overview-of-eye-injuries-in-the-emergency-department.

  6. Jacobs, D. S. Corneal abrasions and corneal foreign bodies: management. Retrieved September 16, 2017, from https://www.uptodate.com/contents/corneal-abrasions-and-corneal-foreign-bodies-management.

  7. Waldman, N., Winrow, B., Denise, I., Gray, A., McMAster, S., Giddings, G., & Meanley, J. (2017). 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. Annals of Emergency Medicine, 02(016).

 

Posted on May 20, 2019 and filed under Ophthalmology.