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2020 OMIG Abstract

Delayed Diagnosis and Presenting Characteristics of Acanthamoeba Keratitis at a Tertiary Medical Center

Nakul S. Shekhawat, MD, MPH, Sidra Zafar, MBBS, Inna Stroh, MD, PhD, Nancy Zhang,
Manjari Sriparna, BS, Zara Ghous, MBBS, Divya Srikumaran, MD, Fasika A. Woreta, MD, MPH
Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD

Purpose: To describe time to diagnosis and initial presenting characteristics of culture-confirmed Acanthamoeba keratitis (AK) cases seen over a seven-year period at a tertiary academic medical center in the United States.

Methods:: Retrospective review of all culture-confirmed AK cases seen at the Wilmer Eye Institute between August 2012 and June 2019. We collected information on patient demographics, time from symptom onset to Acanthamoeba culture collection, known risk factors for AK, misdiagnoses prior to presentation, treatments prior to presentation, presenting logMAR visual acuity, and initial slit lamp examination findings. Differences in continuous variables were assessed via t test.

Results: HA total 45 eyes of 43 patients were diagnosed with culture-confirmed AK. Patients had mean age of 41 years (SD 17) and 22 patients (51%) were female. Patients were symptomatic a mean of 53 days (SD 48) prior to Acanthamoeba culture collection. 14 eyes (31%) were cultured within 28 days of symptom onset while 31 eyes (69%) were cultured over 28 days after symptom onset. 31 eyes (69%) were first evaluated by an outside ophthalmologist. Risk factors for AK included CL wear (43 eyes, 96%), recent ocular trauma (N=4 eyes, 9%), ocular surface disease (N=9 eyes, 20%), herpetic keratitis (N=3 eyes, 7%), and history of LASIK (N=3 eyes, 7%). Most common misdiagnoses prior to referral were herpetic keratitis (N=17 eyes, 38%) and bacterial keratitis (N=9 eyes, 20%). Most common topical medications used prior to referral were antibacterials (N=32 eyes, 71%), corticosteroids (N=19 eyes, 42%), antivirals (N=18 eyes, 40%), and antifungals (N=4 eyes, 9%). Presenting visual acuity was mean 1.13 logMAR (SD 0.77) for all AK eyes with no significant difference observed in eyes with early versus delayed presentation (p=0.03). Most common presenting examination findings included diffuse infiltrates (N=17 eyes, 38%), deep infiltrates (N=16 eyes, 36%), multifocal infiltrates (N=14 eyes, 31%), dendritiform epithelial lesions (N=5 eyes, 11%), ring infiltrate (N=5 eyes, 11%), radial keratoneuritis (N=4 eyes, 9%), hypopyon (N=4 eyes, 9%), and scleritis (N=1 eye, 2%).

Conclusion: The majority of AK eyes were not diagnosed via culture for over 4 weeks after symptom onset. Many AK cases were initially misdiagnosed and/or treated as non-Acanthamoeba infections, likely due to mimicry of other forms of keratitis. Classic findings such as ring infiltrate and radial keratoneuritis were uncommon.

Disclosure: N

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