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Overnight Orthokeratology — A risk factor for microbial keratitis

In a recent issue of Cornea, Tseng et al reported on 9 cases of microbial keratitis associated with overnight orthokeratology. All patients were under the age of 18, and one was as young as 8. The study was performed at a university teaching hospital in Taiwan during a 15-month period.

Six of the 9 patients had some form of microbial confirmation, and 5 had been treated partially before referral, which may have made confirmation more difficult. Documented agents included gram negative organisms and acanthamoeba. The complications were significant, with a corneal opacity in all eyes, glaucoma requiring trabeculectomy in 1 eye, and cataract with secondary angle closure in 1 eye. Four eyes had a best final visual correction of 20/30 or worse, with 1 eye having hand motion only. The denominator is unknown, so an incidence rate or even a prevalence figure cannot be calculated. Presumably, the infectious process is an uncommon to rare occurrence on a statistical basis, but is a relative disaster for the individual.

Although at least 24 eyes with microbial keratitis have been reported in 9 previous studies, this is the largest patient group studied to date, and it shows a worrisome trend. The presence of myopia is high in Taiwan, and as a result, the denominator may be similarly high, but the potential public health threat posed by this treatment is alarming. These patients are young and will have a lifetime of disability, and they don’t make treatment decisions for themselves. At the very least, disclosure of this risk must be included in the information provided to parents who are considering orthokeratology for their children.

REFERENCE

Tseng CH, Fong CF, Chen WL, et al. Overnight orthokeratology-associated microbial keratitis. Cornea. 2005;24:778–782)