Consent was obtained from the children and their guardians after verbal and written explanations of the objectives and possible consequences of the study. This study was approved by the institutional review board of the Eye Hospital of Wenzhou Medical University, and all work was carried out in accordance with the tenets of the declaration of Helsinki. We performed this prospective, nonrandomized, control study to compare peripheral defocus, aberrations, and contrast visual acuity in children wearing MSCL with OK lens and to show the 1-year myopia progression. Thus, it was hypothesized that lower addition limits the myopia control effect of BSCLs and MSCLs.Ī new MSCL designed to mimic the optical performance established in OK lens with highly addition has been recently introduced for myopic control in the clinic. MSCLs of the same design with different levels of add powers also showed that higher addition had a better effect on myopia control in children. However, animal studies suggested that a higher peripheral myopic defocus had a better ability to maintain hyperopia, slow the myopia progression, or counteract the myopiagenic effect. In previous studies, BSCLs and MSCLs were commonly designed with low to moderate additions (+ 0.50 to + 4.00 diopter ), which produced relatively lower retinal peripheral myopia defocus than that from OK lenses. However, different optic designs and additions lead to different myopia control efficacies. Previous studies found that BSCLs and MSCLs significantly slowed axial elongation. An increase in HOAs also causes a decrease in visual quality, noted as a decrease in contrast sensitivity or contrast visual acuity (CVA), which may influence the daily life of children. Several previous studies found a significant increase in spherical aberration (SA), coma, and total HOAs. Peripheral defocus and other optical changes caused by post-OK or wearing MSCL also cause changes in the corneal and retinal higher-order aberrations (HOAs). BSCLs and MSCLs also produce different magnitudes of peripheral myopic defocus with different additions. They found that the lenses turned peripheral hyperopic defocus to myopic defocus and sustained it during the wearing period. Previous studies of children with low to moderate myopia measured horizontal and vertical peripheral defocus after wearing OK lenses. This method has been applied in children for myopia control, as peripheral defocus is proposed to be one of the mechanisms by which OK lenses, BSCLs, and MSCLs slow myopia progression. Previous animal studies found that relative peripheral hyperopia induced by a negative lens produces central axial elongation, whereas peripheral myopic defocus produces axial hyperopia. These are commonly designed for central distance correction and peripheral additions. Another efficient method that is widely recognized is bifocal (BSCL) or multifocal soft contact lenses (MSCL). A meta-analysis showed OK lenses could slow myopia progression by approximately 30% to 60%. OK lens is a common clinical myopia control approach. Orthokeratology (OK) lenses are rigid gas permeable contact lenses with a reverse-geometry design and are intended to be worn at night. Thus, controlling myopia in children of primary school age is important and necessary. The incidence of high myopia is increasing year by year, and some cases are sufficiently serious to cause blindness due to pathological myopia, such as retinal detachment, glaucoma, and myopic choroidal neovascularization. Myopia can develop quickly during primary school ages, and some individuals will develop high myopia in adulthood. Myopia has become a global pandemic in recent decades.
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