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E. Okada, K. Kimbara, K. Iyanaga, N. Tabei, T. Hidaka, M. Nagasaki, T. Yokoyama, H. Kamezawa, N. Mizuki; Longitudinal Analysis of Orthokeratology Outcome for Myopia Correction in Comparison With Other Lenses and Spectacles. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1528.
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© ARVO (1962-2015); The Authors (2016-present)
To report the outcome of Orthokeratology (OK) for myopia correction in comparison with other types of contact lenses and spectacles.
This retrospective study was made on 740 eyes of 371 myopic patients who were prescribed for OK lenses at Okada Eye Clinic for five years from 2004 to 2009. The data analyzed for longitudinal efficacy and safety of OK were taken from patients who attended at least one one-year follow up examination. This data was compared with the clinical data of other soft and hard lenses and spectacles patients.
The ages ranged from 8 to 62 years on commencing OK (mean 26 years). The male: female ratio was 1:1. Ninety-nine percent were bilateral users. The mean k-reading at the flat meridian of the subjects was 42.73 D (39.50 to 45.25) on the initial visit and with OK this had reduced to 41.25 D (37.75 to 44.25) by the final visit. The mean refraction was spherical -3.20 D (0.00 to -9.50) and cylinder -0.59 D (0.00 to -1.75) and this was reduced to spherical +0.03 D (+1.50 to -1.50) and cylinder -0.50 D (0.00 to -2.00) respectively. The mean LogMAR visual acuity improved from 1.12 (0.1 to 1.7) to -0.01 (-0.2 to 0.7). Eighty-five percent of the subjects achieved the target power correction within spherical ±0.50 D. Eight percent and three percent reported lens breakage and loss respectively. The drop out rate was 11% and 66% did not attend the 1-year follow up. Over the five years the following complications were observed: slight-to-moderate superficial punctate keratitis (SPK) 14%, allergic conjunctivitis 9%, and dry eye 3%. These complications were observed with other soft lenses in 3%, 9%, and 3% and with hard lenses in 5%, 6%, and 2% of cases respectively. In patients under 18 years old, over the five year period the mean spherical power tended to increase yearly for myopia correction with soft lenses by -0.18 D, hard lenses by -0.42 D, and spectacles by -0.31 D while OK patients stayed with the initial corrective power.
This longitudinal analysis supports the positive usefulness of OK which results in good clinical outcomes for the correction of myopia and showed a suppression effect against myopic shift. SPK was seen more frequently however, with OK than with other lenses, and the no-show rate for follow up was high. Periodic follow-up should be maintained carefully for OK along with proper direction and education to the patients to prevent severe complications.
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