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Takahiro Hiraoka, Yoshifumi Okamoto, Fumiki Okamoto, Tetsuro Oshika; Post-marketing surveillance of overnight orthokeratology: 3-year follow-up study in Japan. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):6088.
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© ARVO (1962-2015); The Authors (2016-present)
In April 2009, an overnight orthokeratology lens (α Ortho®-K, Alpha Corporation) was first approved in Japan. The Japan Ministry of Health obliged the company to do a post-marketing surveillance (PMS) of the lens for 3 years. We herein report the results of the PMS.
The data of 69 patients (136 eyes) enrolled in the PMS were analyzed. The patients’ age was from 7 to 48 years old. Efficacy of the lens was evaluated based on the analyses of changes in refraction, visual acuity, intraocular pressure, corneal thickness and corneal endothelium. Adverse events and drop-out cases were also evaluated. Moreover, the results were compared between age ≥ 20 and age < 20 groups.
Refraction and uncorrected visual acuity had changed significantly after one day of lens wear. They further improved until 2 weeks, and remained stable thereafter. There were no significant changes in IOP and endothelial cell density during the study period. Adverse events were observed in 18 eyes; corneal staining in 10 eyes, bulbar conjunctival hyperemia in 2 eyes, and superior tarsal papillary hypertrophy in 2 eyes, etc.. All patients with adverse events resumed the lens wear after healing each condition. Ten patients discontinued myopic correction with orthokeratology and dropped out the PMS. The reasons were “inconvenient at the time for work and driving” (6 patients) and “inability to keep follow-up examinations due to individual circumstances” (4 patients).
According to Japanese guidelines for orthokeratology, it is recommend to apply orthokeratology lenses only to adults. However, 54 percentages of the patients were less than 20 years old. The results of PMS showed acceptable safety and efficacy of α Ortho®-K, and no differences between the two age groups. Appropriate prescription, sufficient education to patients, and periodical follow-up examinations seem to minimize serious problems in clinical practice of orthokeratology in both adults and children.
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