Abstract
Purpose::
Acanthamoeba is a rare cause of infectious keratitis. Previously identified risk factors for acanthamoeba keratitis (AK) include contact lens wear, trauma, and exposure to fresh-water or salt-water sources. In recent years, outbreaks of AK have been reported worldwide in the United States (US), England, India and China. The purpose of this study is to examine the clinical experience of AK at a large eye hospital in the northeastern US.
Methods::
A retrospective case review was completed of patients with infectious keratitis whose corneal cultures were positive for acanthamoeba between January 2000 and October 2006. The clinical characteristics and visual outcomes were examined. The MEEI Institutional Review Board approved this study.
Results::
In the four years from January 2000 to December 2003, only four cases of AK occurred. From January 2004 to October 2006, 11 patients were diagnosed with AK. One patient had bilateral disease. The medical records from these 12 eyes with culture-proven AK were reviewed.The average patient age was 41 years; 7 of 11 patients were male. At initial presentation, the best recorded visual acuity (VA) was 20/400 or less in 50% of eyes. The average time from presentation to diagnosis of AK by corneal culture was 25.9 days (range, 6 to 101 days). The average time of follow-up was 234 days (range, 7 to 775 days). The majority of cases were recalcitrant to medical therapy alone, necessitating therapeutic penetrating keratoplasty in 8 of 12 eyes. In the 8 eyes that underwent surgical intervention, the final VA was unchanged in 2 eyes, improved in 4 eyes, and worse in 2 eyes when compared to the VA at presentation. For all cases of AK reviewed, the final visual acuity was unchanged or improved in 9 of 12 eyes.Risk factors associated with AK in this series included contact lens wear (7/12), exposure to contaminated water sources (8/12), ocular trauma (3/12), chronic ocular surface disease (3/12), and concomitant bacterial or fungal keratitis (3/12).
Conclusions::
AK is an uncommon corneal infection. We have seen an increase in the number of cases in the past 3 years (11) when compared to the previous 4 years (4 cases total). The etiology of this alarming trend is not known but may be related to factors also involved in the recent epidemic of fungal keratitis, such as corneal staining caused by mismatch between contact lens care solutions and contact lens materials. Exposure to contaminated water sources continues to be a major risk factor. AK infections are difficult to treat and frequently require surgery for cure. It is important for ophthalmologists to maintain a high level of surveillance for these potentially devastating infections.
Keywords: Acanthamoeba • keratitis • cornea: clinical science