Efficacy of a Dual Focus Contact Lens and Factors Influencing Myopia Progression in a 3-Year Trial

Abstract

Purpose: To report the efficacy of a dual focus contact lens (DFCL) designed to slow the rate of myopia progression and identify factors associated with myopia progression.

Methods: Myopic children aged 8 to 12 years, with no prior CL experience, were enrolled in a prospective, randomised, double-masked, controlled multicenter study at 4 investigational sites. Subjects wore either DFCL or a single vision contact lens (SVCL) both omafilcon A (CooperVision). Participants’ initial myopia ranged from 0.75 to 4.00D and astigmatism was < 1.00D.
Cycloplegic autorefraction (SERE) and axial length (AL) were measured at baseline and every 12 months for 3 years. A linear mixed model (LMM), including fixed factors such as lens type, site, sex, visit and their interactions, was used to compare the adjusted change in SERE and AL. The model also included covariates such as age, baseline refraction and wearing times.

Results: 144 subjects were dispensed study lenses, 74 (control group) and 70 (test group) . There was no significant difference (p > 0.05) in demographic factors influencing myopia progression between groups. After 3 years 108 subjects (56 SVCL; 52 DFCL) completed the study. The estimated mean difference in SERE and AL was 0.38D (CI 0.22 to 0.55); 0.54D (CI 0.37 to 0.70) and 0.69D (CI 0.51 to 0.85) and 0.14mm (CI 0.06 to 0.22); 0.23mm (CI 0.15 to 0.31) and 0.29mm (CI 0.21 to 0.38) at 12, 24 and 36 month visits respectively. Significantly higher progression was found for the control group at each visit (p < 0.001). Change in SERE was significantly correlated to change in AL at 12, 24 and 36 month visits (r=-0.77, r=-0.86 and r=0.90 p < 0.0001, respectively). Age, site and gender were significant factors in SERE and AL change (p > 0.05), interaction of these factors with lens type were not significant (p > 0.05). Baseline myopia or wearing time was not a significant factor on myopia progression (p > 0.05) in this cohort. 

Conclusion(s): DFCL reduced significantly myopia progression by 59%, 54% and 52% and axial elongation by 58%, 50% and 45% at 12, 24 and 36 months respectively when compared to a single vision contact lens. The treatment effect is independent of age; gender; ethnicity and baseline refractive error.