AIMS: Modern orthokeratology (ortho-k) using reverse geometry lens designs is being widely used for myopia reduction world-wide although there has been no well-controlled clinical trial of this procedure. This paper reports on the efficacy and predictability of an ortho-k procedure using the OK-74 lens design (now known as OK-704). METHODS: We carried out a 100-day, controlled, randomised clinical trial in which 14 subjects underwent ortho-k and a further 14 were fitted with aligned rigid contact lenses. RESULTS: The mean reduction in myopia was 1.50 (SD 0.45) D in the ortho-k group and 0.01 (SD 0.20) D in the control group. Unaided vision improved by -0.64 (SD 0.22) logMAR units in the ortho-k group, compared with -0.09 (SD 0.11) units in the control group. Variables which correlated with refractive change were corneal thickness, p-value of the nasal semi-meridian and the difference between central and peripheral corneal powers. A multiple factors model can account for 72% of the refractive change. CONCLUSIONS: Ortho-k using the OK-74 lens design achieved an average myopia reduction of 1.50 D. The model developed can provide an estimate of the refractive change likely to occur in ortho-k, a matter of importance to both clinician and patient.
RCT Entities:
AIMS: Modern orthokeratology (ortho-k) using reverse geometry lens designs is being widely used for myopia reduction world-wide although there has been no well-controlled clinical trial of this procedure. This paper reports on the efficacy and predictability of an ortho-k procedure using the OK-74 lens design (now known as OK-704). METHODS: We carried out a 100-day, controlled, randomised clinical trial in which 14 subjects underwent ortho-k and a further 14 were fitted with aligned rigid contact lenses. RESULTS: The mean reduction in myopia was 1.50 (SD 0.45) D in the ortho-k group and 0.01 (SD 0.20) D in the control group. Unaided vision improved by -0.64 (SD 0.22) logMAR units in the ortho-k group, compared with -0.09 (SD 0.11) units in the control group. Variables which correlated with refractive change were corneal thickness, p-value of the nasal semi-meridian and the difference between central and peripheral corneal powers. A multiple factors model can account for 72% of the refractive change. CONCLUSIONS: Ortho-k using the OK-74 lens design achieved an average myopia reduction of 1.50 D. The model developed can provide an estimate of the refractive change likely to occur in ortho-k, a matter of importance to both clinician and patient.
Authors: Jimmy S H Tse; Jimmy K W Cheung; Gigi T K Wong; Thomas C Lam; Kai Yip Choi; Katherine H Y So; Christie D M Lam; Andes Y H Sze; Angel C K Wong; Gigi M C Yee; Henry H L Chan Journal: Transl Vis Sci Technol Date: 2021-09-01 Impact factor: 3.283