High Myopia–Partial Reduction Ortho-k: A 2-Year Randomized Study

• Published in: Optometry and vision science Vol. 90; no. 6; pp. 530 - 539
• Main Authors: Charm, Jessie, Cho, Pauline
• Format: Journal Article
• Language: English
• Published: United States American Academy of Optometry 01.06.2013
• Subjects: Axial Length, Eye; Child; Corneal Topography; Disease Progression; Eyeglasses; Female; Humans; Male; Myopia, Degenerative - diagnosis; Myopia, Degenerative - physiopathology; Myopia, Degenerative - therapy; Orthokeratologic Procedures; Refraction, Ocular - physiology; Single-Blind Method; Treatment Outcome
• DOI: 10.1097/OPX.0b013e318293657d
• ISSN: 1040-5488; 1538-9235

PURPOSETo investigate if the combination of partial reduction (PR) orthokeratology (ortho-k) and spectacles for residual refractive errors in the daytime was effective to slow myopic progression in high myopic children. METHODSHigh myopic children (aged 8 to 11 years) with spherical equivalent refraction at least −5.75 diopters (D) and myopia −5.00 D or more myopic were recruited and randomly assigned into PR ortho-k and control groups. Subjects in the PR ortho-k group were fitted with custom made four-zone ortho-k lenses with target reduction of 4.00 D for both eyes, and the residual refractive errors were corrected with single-vision spectacles for clear vision in the daytime. Control subjects were fully corrected with single-vision spectacles. Axial length of each eye of all subjects was measured with the IOLMaster at 6-month intervals by a masked examiner. This study was registered at www.clinicaltrial.gov with the identifier NCT00977236. RESULTSFifty-two subjects were recruited and randomized to the PR ortho-k and control groups. Twelve PR ortho-k and 16 control subjects completed the study. Compared with the residual refractive errors at the 1-month visit (after stabilization of ortho-k treatment), the median increase in noncycloplegic residual myopia at the 24-month visit was 0.13 D. In the control group, the median increase in myopia was 1.00 D at the end of the study. The mean ± SD increases in axial length were 0.19 ± 0.21 mm in the PR ortho-k group and 0.51 ± 0.32 mm in the control group (95% confidence interval, −0.55 to −0.12; unpaired t test, p = 0.005). CONCLUSIONSThis single-masked randomized study showed that PR ortho-k effectively slowed myopic progression in high myopes. Axial length elongation was 63% slower in PR ortho-k–treated children compared with children wearing spectacles.