Does more peripheral defocus increase the myopia control effect? Evidence from the BLINK study

Title: Peripheral Defocus and Axial Eye Growth in the Bifocal Lenses in Nearsighted Kids (BLINK) Study

Authors: David A. Berntsen (1), Anita T. Gostovic (1), Loraine T. Sinnott (2), Moriah A. Chandler (1), Juan Huang (3), Ann Morrison (2), Lisa A. Jones-Jordan (2), Jeffrey J. Walline (2), and Donald O. Mutti (2) for the BLINK Study group

1: College of Optometry, The University of Houston, TX
2: College of Optometry, The Ohio State University, Columbus, OH
3: School of Optometry, The University of Alabama at Birmingham, Birmingham, Alabama, United States

Reference: ARVO 2021 abstract and video presentatio

The BLINK study found that +2.50 Add centre-distance multifocal contact lenses (MFCLs) slowed myopia progression but the +1.50 Add didn't. This leads to a dose-response hypothesis: a presumption that higher adds will produce a greater myopia control effect. In this study, the authors evaluated change in peripheral defocus with the MFCLs and found that:

• The +2.50 Add MFCLs created an average of just under 1.00D myopic shift at 40 degrees peripherally compared to single vision, during distance and near viewing
• The myopic shift in defocus with +2.50 Add MFCLs only explained about 15% of the reduction in axial length growth.

This indicates that a dose-response to peripheral defocus does not fully explain the myopia control efficacy of MFCLs - perhaps exceeding a threshold or other mechanisms are involved.

What does this mean for your clinical practice? The +2.50 Add MFCL has shown myopia control efficacy in the previously published BLINK study, although it is not regulatory indicated for slowing myopia progression. Using higher adds than +2.50 in attempt to achieve even stronger myopia control effect may have a very small but clinically insignificant impact.

Purpose:  The BLINK Study was a 3-year randomised clinical trial that found +2.50D add centre-distance multifocal soft contact lenses (MFCLs) slowed myopia progression versus +1.50D add MFCLs and single vision contact lenses (SVCLs).  In this analysis, we explore the relationship between peripheral defocus and axial growth.

Methods: 294 myopic children 7-11 years old (60% female) were enrolled (mean ± SD age = 10.3 ± 1.2years).  Children had myopia of -0.75D to -5.00D (most hyperopic meridian) and <1.00D astigmatism at enrolment (mean ± SD spherical equivalent (M) = -2.39 ± 1.00D).  Children were randomly assigned to one of three lenses: SVCL, +1.50 add MFCL, or +2.50 add MFCL.  Autorefraction (horizontal meridian; right eye) was measured while wearing CLs centrally (line of sight) and ±20°, ±30°and ±40° from the line of sight while viewing a near target (30cm) and also at distance after cycloplegia.  Each child’s defocus (M) profile at distance and near were fit using quadratic equations.  Models of the first-year change in axial length (measured by optical biometry) were fit including the quadratic coefficient (Qc) for defocus at distance or near, central M, gender, study site, and age.

Results:  After 1 year, mean axial growth was on average 0.13mm less in the +2.50 add group (p<.001) and 0.03mm less in the +1.50 add group (p = .11) versus SVCLs.  Compared to SVCLs, peripheral defocus at distance was more myopia (less positive Qc) with MFCLs (Figure 1).  At the 1-year visit, the average Qc in the +2.50 versus the SVCL group was .0005 D/degree2 less at distance and .0004 D/degree2 less at near.  More myopic peripheral defocus at distance and at near in the +2.50 group was associated with less axial growth (distance: ß=31, or .016mm less axial growth, p=.005; near: ß=49, or .020mm less axial growth, p<0.01).

Conclusions:  More myopic peripheral defocus at distance and near in children wearing +2.50 add MFCLs compared to SVCLs was associated with less axial growth in the BLINK Study, but not by a clinically meaningful amount.  The small association suggests that a linear dose-response to peripheral defocus may not fully explain the effects of MFCLs on axial growth.  Exceeding a threshold amount of peripheral myopic defocus or mechanisms other than peripheral defocus may cause the significantly slowing of axial growth seen with MFCLs.

Disclosures:  David A. Bernsten, Bausch+Lomb (Code F (Financial Support)), Visioneering Technologies, Inc. (Code C (Consultant)); Anita T. Gostovic, Bausch+Lomb (Code F (Financial Support)); Loraine T. Sinnott, Bausch+Lomb (Code F (Financal Support)); Moriah A. Chandler, Bausch+Lomb (Code F (Financial Support)); Juan Huang, Bausch+Lomb (Code F (Financial Support)); Ann Morrison, Bausch+Lomb (Code F (Financial Support)); Lisa Jordan, Bausch+Lomb (Code F (Financial Support)); Jeffrey J. Walline, Bausch+Lomb (Code F (Financial Support)), SightGlass (Code C (Consultant)); Donald O. Mutti, Bausch+Lomb (Code F (Financial Support)), Welch Allyn (Code C (Consultant))