Comparing soft multifocal and orthokeratology contact lens efficacy

Paper title: Retardation of Myopia by Multifocal Soft Contact Lens and Orthokeratology: A 1-Year Randomized Clinical Trial

Authors: Fang, Jianxia (1); Huang, Zhu; Long, Yan; Zhu, Miaomiao; Wu, Qin; Chen, Xiaojun; Xv, Wei; Du, Chixin

1. Department of Ophthalmology (J.F., Y.L., M.Z., Q.W., X.C., W.X., C.D.), The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, P. R. China; and Department of Ophthalmology (Z.H., C.D.), The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang Province, P. R. China.

Date: Aug 2022

Reference:  Fang J, Huang Z, Long Y, Zhu M, Wu Q, Chen X, Xv W, Du C. Retardation of Myopia by Multifocal Soft Contact Lens and Orthokeratology: A 1-Year Randomized Clinical Trial. Eye Contact Lens. 2022 Aug 1;48(8):328-334

[Link to open access paper]

The purpose of this single-blind, parallel clinical trial was to compare the myopia control efficacy of multifocal soft contact lenses (MFSCL), orthokeratology (Ortho-kCL) and single vision spectacle lenses.

The participants were Chinese children (n = 81) aged between 7 and 15yrs with myopia between -1.00 and -8.00D and no history of prior myopia control. They were randomly assigned to wear either MFSCL (BioThin, Bio Optic, China) or orthokeratology (Paragon CRT) in the treatment groups or single vision spectacle lenses (SVS) for myopia control (Carl Zeiss) in the control group. The wear times requested were: 12hrs per day (MFSCL), for at least 8hrs overnight (Ortho-kCL) and from 8am to bedtime (SVS) and all groups for a period of one year.

Measurements at baseline included cycloplegic auto-refraction, axial length (AL) and corneal endothelial cell density (CECD). These were repeated at 6- and 12-month visits for the MFSCL and SVS groups. Changes in AL for the Ortho-kCL group were measured at 6- and 12-months and CECD at 12 months only.

Sixty-six children completed the study (MFSCL, n = 22, Ortho-kCL, n = 20, SVS, n = 24). There were no significant differences between them at baseline. At the 6-month visit, there were no significant changes in SER for the MFSCL and SVS groups and AL values were significantly slower for the MFSCL group compared to the SVS group, but not for the Ortho-kCL group where there was no significant slowing.

At the 1-yr visit, the myopia progression saving was 37% in the MFSCL group compared to the SVS group (-0.591D v -0.938D). The adjusted AL values showed a saving of 26.8% and 24.4% for the MFSCL and Ortho-kCL groups respectively, compared to the SVS group, and these interventions were similar. There was no significant differences seen for CECD for all 3 groups, after 6 or 12mths.

Soft multifocal and Ortho-k contact lenses gave a similar slowing of myopia progression over a year compared with the single vision myopia control spectacle lens group. With no decrease in corneal endothelial cell density, these lenses are a safe option to recommend.

Further studies could establish:

• The correction zone size and defocus required to optimise myopia control efficacy. The lens design worn in this study used +6D to induce defocus for the myopia control effect. The results from this defocus were found to be similar for lens designs used in other studies with +1.00, +2.00 or +2.50D defocus.^1-5
• The ideal wear period to achieve the full benefit of myopia control from a given lens design. The multifocal group were seen to have less AL elongation and more myopia control effect at the 1^st 6-mth visit than at the 12mth visit. Axial length growth and myopia progression slows with a child’s age and the therapeutic effect of myopia control may appear less obvious, even if the treatment shows a similar percentage change at all age stages.
• If lifestyle and near work impact on the lens efficacy. Decreased time outdoors and increased near work are thought to be risk factors for myopia development⁶
• If the corneal cell density remains unaffected with longer wear periods.
• The true difference in myopia control effects between MFSCL and Ortho-k. 

Title: Retardation of Myopia by Multifocal Soft Contact Lens and Orthokeratology: A 1-Year Randomized Clinical Trial

Authors: Jianxia Fang, Zhu Huang, Yan Long, Miaomiao Zhu, Qin Wu, Xiaojun Chen, Wei Xv, Chixin Du

Purpose: This randomized, single-blind, clinical trial compared the effectiveness of multifocal soft contact lenses (MFSCLs), orthokeratology contact lenses (Ortho-k CLs), and single vision spectacles (SVSs) for myopia control.

Methods: Sixty-six eligible Chinese subjects, aged 7 to 15 years old with cycloplegic refraction measurements between -1.00 and -8.00 diopters (D), astigmatism not more than 1.00 D, and no history of myopia control treatment, were randomly assigned to wear MFSCLs, Ortho-k CLs, or SVSs for 1 year. For all three groups, baseline measurements of cycloplegic refraction, axial length (AL), and corneal endothelial cell density (CECD) were made. At the 6- and 12-month follow-up visits, changes in cycloplegic refraction, AL, and CECD were measured in the MFSCL and SVS groups. For the Ortho-kCL group, only changes in the AL were measured at 6 and 12 months, and CECD was measured at the 12-month follow-up visit.

Results: After 1 year of lens wear, myopia progression of the SVS group, -0.938±0.117 D, was greater than that of the MFSCLs group, -0.591±0.106 D (P=0.032). Thus, MFSCLs reduced the rate of myopia progression by 37.0% compared with the SVSs. The AL elongations after 1 year were 0.30±0.03 mm for MFSCLs (P=0.027 vs SVSs), 0.31±0.04 mm for Ortho-k CLs (P=0.049 vs SVSs), and 0.41±0.04 mm for SVSs. Compared with the SVS group, the reduction in AL elongation was 26.8% and 24.4% in the MFSCL and Ortho-k CL groups, respectively. There were no significant differences in CECD among the three groups (P>0.05).

Conclusions: Compared with SVSs, wearing MFSCLs and Ortho-k CLs significantly delayed myopia progression. MFSCLs and Ortho-k CLs are safe and promising methods of myopia control

[Link to open access paper]