Efficacy of elastic Breath-O Correct orthokeratology on myopia control in a 1-year study period

Abstract

Purpose : This study is to evaluate the myopia reduction effect and myopia control efficacy of the novel elastic Breath-O Correct orthokeratology (OK) lenses. Methods : A total of 85 subjects aged 9 to 12 years with spherical equivalent refraction (SER) between -1.00D and -4.00D were recruited, then randomly assigned into OK (n=49) or spectacle control (n=36) groups. Breath-O Correct lenses were prescribed in OK group with routinely scheduled aftercares. Corneal topography, SER, unaided and best-corrected visual acuity in LogMAR (BCVA), anterior chamber depth (ACD), and axial length (AL) were measured at baseline and 1-year visit. For the control group, update of spectacles was indicated if there was a 0.50D difference in spherical or cylindrical power by subjective refraction in a 6-month follow-up. Results : Seventy-one subjects (OK: 42, Control: 29 Age 9.46 ±1.32 years) completed the 1-year study. Seven OK subjects withdrew due to poor visual quality, inconvenient lens care, and COVID-19 pandemic. Seven control subjects withdrew due to fast myopia progression and COVID-19 pandemic. In OK group, the 1-year simulated flat and steep K decreased significantly (Flat K: -1.57±0.95D; Steep K:-1.59±1.07D; p<0.001) with a mean unaided visual acuity of 0.09±0.13. The mean dry subjective SER in control and OK groups were -2.92±1.32D and -0.07±0.66D (p<0.001) respectively without significant difference in BCVA (Control: 0.01±0.04, OK: 0.00±0.05; p>0.05). The mean AL elongation was significantly different between two groups (Control: 0.35±0.2mm, OK: 0.14±0.17mm, p<0.001). A significant ACD elongation was also noted in control group but absent in OK group (Control: 0.073±0.096mm, p<0.001; OK: -0.054±0.326mm p>0.05). RM-ANOVA with post-hoc Bonferroni correction revealed significant interaction between OK treatment and the rate of myopia progression in 1 year (p<0.001). Conclusions : The novel elastic Breath-O Correct OK lens effectively retarded AL elongation, and hence, myopia progression in school-aged children without compromising BCVA and with maintenance of good unaided daytime vision.