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Increased Acanthamoeba Risk
Ruling out infection essential in minors using orthokeratology contact lenses. Roibeárd O’hÉineacháin reports from the ESCRS Virtual Winter Meeting 2022
Myopic patients using orthokeratology lenses can be at increased risk of sight-threatening acanthamoeba keratitis. Such cases require close management to ensure an optimum outcome, advises Magdalena Niestrata-Ortiz MSc, PhD.
“Acanthamoeba keratitis is an emerging complication of orthokeratology in young myopes. Although myopia progression remains a significant public health issue, the proportion of acanthamoeba keratitis amongst minors using orthokeratology lenses appears to exceed the expected risk profile,” she told delegates.
At a Cornea Day session of the meeting, Dr Niestrata-Ortiz described the case of a 14-year-old female patient who presented at a specialist corneal clinic with a one-week history of painful, red, photophobic eyes. She had been using rigid gas permeable (RGP) orthokeratology lenses for myopia overnight only. She was not using other contact lenses and followed rigorous contact lens hygiene, with no reported use of tap water.
The patient’s symptoms failed to improve when she discontinued using the lenses immediately following the onset of symptoms and despite having used topical antibiotics. Her vision at presentation was logMAR 1.0 (pinhole 0.7) and 1.0 (pinhole 0.8) in the right and left eye, respectively. Slit-lamp biomicroscopy showed pseudodendritiform epitheliopathy, radial perineuritis, and severe limbitis.
Dr Niestrata-Ortiz and her associates made a clinical diagnosis of acanthamoeba keratitis, which they subsequently confirmed by PCR taken at presentation. They proceeded with treatment through hourly topical administration of Polyhexamethylene Biguanide (PHMB) 0.02% and Brolene 0.1% to both eyes.
During a close follow-up at the cornea clinic, the patient showed signs of improvement of her symptoms two days after starting the treatment. However, one week later, her eyes were more inflamed with significant bilateral radial perineuritis. Therefore, the clinicians increased the strength of topical PHMB prescription to 0.06%.
Within one week, the patient started to improve symptomatically. She underwent epithelial debridement in the right eye to remove any infected surface cells and promote better drop penetration. She continued to improve symptomatically and clinically throughout the next three months, at which point Brolene was stopped, and monotherapy with PHMB 0.06% continued. Four months after commencing treatment, her symptoms improved significantly with a normal corneal appearance and best-corrected vision with glasses of logMAR 0.30 (pinhole 0.12) and 0.24 (pinhole 0.08) in the right and left eye, respectively. She continues to improve on current treatment.
Dr Niestrata-Ortiz noted that this patient developed acanthamoeba keratitis despite using the orthokeratology contact lenses as recommended. That is, she always used the contact lens solution and never tap water to clean and store the lenses, never took showers with the lenses on, and only wore them at night. A recent review in the US showed an incidence of acanthamoeba keratitis of 13% among minors using the orthokeratology lenses.
“Caution should be exercised when selecting appropriate treatment options for myopia, and alternatives should be considered. In young patients using orthokeratology who develop keratitis, there is a high index of suspicion of acanthamoeba. Prompt diagnosis and treatment is paramount for good clinical outcomes,” Dr Niestrata-Ortiz concluded.
Magdalena Niestrata-Ortiz MSc, PhD, is in the Department of Ophthalmology, Western Eye Hospital, London, UK. smgxnie@ucl.ac.uk
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