Corneal abrasion with stromal stain
Can you use this image and the case below to identify the cause of this patient's painful red eye?
A 22-year-old man who wears daily disposable soft contact lenses presented with a painful, red right eye for 5 days duration. He last wore his contact lenses for 3 hours at the gym, 3 days before the initial onset. He reported that he does not regularly use any contact lens care systems. Upon examination, a horizontal 1 mm linear corneal abrasion was noted with stromal stain. He was initially treated with ofloxacin ophthalmic solution every 2 hours while awake. At his follow-up appointment 2 days later, the area of corneal stain worsened (see image) and he reported greater eye pain.
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Acanthamoeba keratitis is frequently misdiagnosed as herpetic, bacterial or mycotic keratitis, and is often mistreated due to the shared signs and symptoms between these keratitis types.1 The “telltale sign” of Acanthamoeba is not a sign at all—it’s a symptom. Along with the physical presentation, pain associated with this infection usually is severe and worsens with each clinical visit visit.2 The main risk factors include extended, repeated use of the same contact lenses (daily disposables have a lower risk), use of contact lenses during bath and cleaning them with tap water.3 Additional risk factors can include corneal surface damage and exposure of the lens to contaminated water.1
A review published in the Journal of Current Ophthalmology highlighted additional signs that can prompt clinicians to consider Acanthamoeba keratitis.4 These include chameleon-like epithelial changes (“dirty epithelium,” pseudodendritiformic epitheliopathy, epithelial microerosions, and microcysts), multifocal stromal infiltrates, ring infiltrates, and peripheral perineurial infiltrates.4
This patient also neglected to use proper hygiene for his contact lenses. Research shows that prior to the development of soft contact lenses, Acanthamoeba keratitis was actually extremely rare.4 The association between Acanthamoeba keratitis and contact lens wear has been firmly established and may account for up to 95% of reported cases.4 The Acanthamoeba is most frequently transferred onto the soft contact lens via tap water, which wearers will sometimes incorrectly use to clean their lenses. Research shows infections can be almost entirely avoided by using lens disinfecting solutions over water rinses.4
The incidence of Acanthamoeba is much lower in patients who use rigid lenses. A study of contact lens wearers in the Netherlands showed a low incidence, which researchers attributed to the greater proportion of Dutch contact lens wearers who used rigid gas-permeable lenses.5
The keratitis caused by Acanthamoeba infection is severe and can lead to corneal scarring and permanent vision loss.4 Appropriate treatment should be promptly started, and can include polyhexamethylene biguanide (0.02% PHMB) or biguanide-chlorhexidine in combination with propamidine (0.1%) or hexamidine (0.1%).6
During the healing process epidemic keratoconjunctivitis-like infiltrates may appear and can last for several weeks. Topical steroids should not be used as they can reactivate the cyst formations to the active trophozoite form.7 They should not be used unless concurrent amoebicidal is underway.7
Matthew Garston, OD, is an adjunct professor at the New England College of Optometry and a senior staff optometrist in the medical department at MIT.
- Szentmáry N, Daas L, Shi L, et al. Acanthamoeba keratitis – clinical signs, differential diagnosis and treatment. J Curr Ophthalmol. 2019;31(1):16-23.
- Kozak A, Hong A, Feldman B, et al. Acanthamoeba keratitis. Eyewiki – American Academy of Ophthalmology. eyewiki.aao.org/Acanthamoeba_Keratitis. Updated March 14, 2020. Accessed September 30, 2020.
- Scruggs BA, Quist TS, Salinas JL, Greiner MA. Notes from the Field: Acanthamoeba Keratitis Cases – Iowa, 2002-2017. MMWR Morb Mortal Wkly Rep. 2019;68(19):448-449.
- Ibrahim Y, Boase D, Cree I. How could contact lens wearers be at risk of acanthamoeba infection? A review. J Optom. 2009;2(2):60-66. doi: 10.3921/joptom.2009.60
- Cheng K, Leung S, Hoekman H, et al. Incidence of contact lens-associated microbial keratitis and its related morbidity. Lancet. 1999;354:181-185. doi: 10.1016/S0140-6736(98)09385-4
- Lim N, Goh D, Bunce C, et al. Comparison of polyhexamethylene biguanide and chlorhexidine as monotherapy agents in the treatment of Acanthamoeba keratitis. Am J Ophthalmol. 2008;145(1):130-5. doi: 10.1016/j.ajo.2007.08.040
- McClellan K, Howard K, Niederkorn J, Alizadeh H. Effect of steroids on acanthamoeba cysts and trophozoites. Invest Ophthalmol Vis Sci. 2001;42:2885-2893.