Myopia Control Using Soft Bifocal Lenses

The purpose of this study is to evaluate whether bifocal soft contact lenses (CLs) with low addition and nasally decentered optical zone are effective in controlling myopic progression in children. Visual manipulations induced by multifocal soft CLs with high addition have been shown to inhibit eye growth and myopia development in children by recent studies. Several theories have been proposed including alteration in peripheral defocus, reduced accommodation demand, alterations in binocular vision status and increased ocular higher order aberrations. However, those theories remain to be proven and the optical properties and performance of multifocal soft CLs have not been investigated in children.

Visual manipulations induced by multifocal soft contact lenses (CLs) with high addition (+2.00 D or above) have been shown to inhibit eye growth and myopia development in children with up to 25-50% efficacy by recent studies. Several theories have been proposed including; alteration in peripheral defocus, reduced accommodation demand, alterations in binocular vision status and increased ocular higher order aberrations, which remain to be proven. However, the effect of controlling myopic progression by bifocal CLs with low addition has not been studied. Several studies have shown that multifocal soft CLs can induce changes in ocular aberrations and degradation of image qualities in adults, whereas the optical properties and performance of multifocal soft CLs have not been investigated in children. Due to the differences in ocular structure and function, for instance, the pupil size and accommodation response, the performance of multifocal CLs in children may vary compared with that in adults. As a result, it is essential to assess the optical quality of these lenses worn by children for myopia control, through COAS (Complete Ophthalmic Analysis System). The aim of this randomized clinical trial is to evaluate myopic progression in children wearing soft bifocal with low addition CLs (Menicon 2 week Duo **) used as daily disposable lenses, compared to control subjects wearing single-vision spectacles. Myopia progression quantified by changes in axial length (AL) and cycloplegic refractive error (Rx) will be monitored for 2 years with single-masking. The optical performance of bifocal CLs worn by children will also be investigated. (**this lens is currently commercially available in Japan only. The oxygen permeability (Dk) is 34 with 72% water content, FDA group Ⅱ.)

Device: Bifocal soft contact lenses Use of bifocal contact lenses with nasally decentered optical zone to control the progression of myopia

Evaluate the changes in cycloplegic axial length in children wearing bifocal soft contact lenses with low addition used as daily disposable lenses compared to control subjects wearing single-vision spectacles for two years with single masking and randomisation

Evaluate the changes in cycloplegic refractive error in children wearing bifocal soft contact lenses with low addition used as daily disposable lenses compared to control subjects wearing single-vision spectacles for two years with single masking and randomisation

Assess changes in aberration profile by COAS (Complete Ophthalmic Analysis System) over a period of 2 years

Assess the aberration profile of children wearing bifocal soft contact lenses by COAS (Complete Ophthalmic Analysis System) over a period of 2 years

Inclusion Criteria: Refractive sphere: -0.75 D to -4.50 D Refractive cylinder: not exceed 1.00 D Spherical equivalent: -0.75 D to -5.00 D Best corrected distance VA (LogMAR): 0.14 or better in each eye and 0.10 or better in both eyes Difference in refractive error (spherical equivalent) in the two eyes: not exceed 1.00 D Exclusion Criteria: Prior history of myopia control treatment Contraindication to contact lens wear Binocular anomalies (e.g. strabismus)

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