New data from NaturalVue PROTECT (PROgressive myopia Treatment evaluation for NaturalVue multifocal Contact lens Trial), a randomised clinical trial with 145-subjects, has identified a link between pupil size and myopia progression control.1

The range of pupil diameters in the study cohort varied from 2–7 mm, and a significant relationship between pupil size and myopia progression control was found – the larger the subject’s pupil, the greater the treatment effect over the 12-month study period (p<0.01).

While smaller pupil diameters are typically associated with advancing age, a study by Xu et al., that investigated the range of pupil diameters in pre-schoolers in China, found the same range (2–7 mm) in myopic preschool children (n=3468).2

More importantly, NaturalVue PROTECT found that the change in cycloplegic spherical equivalent refraction, regardless of pupil diameter, was </= 0.25D over the 12-month period. A similar relationship was seen with axial length (p<0.01).

According to Visioneering Technologies (VTI), manufacturer of NaturalVue Multifocal, the data suggests that regardless of pupil size, most children will achieve a significant treatment effect with NaturalVue Multifocal.

Dr Ashley Tuan, VTI’s Chief Medical Officer, described the new as “very exciting”.

She cited research, which has shown that the magnitude of relative plus reaching the retina3 and the location of that plus relative to the fovea4 are both factors that influence the efficacy of an intervention, and said “the catenary curve design of NaturalVue Multifocal satisfies both those criteria”.

However, she noted that “the child’s pupil size will impact the available space for the contact lens optics to create the relative plus at the retinal plane.”

Dr Tuan said the third key factor for a successful myopia treatment effect is that the intervention must be well tolerated.

In the case of NaturalVue 1 day multifocal, the PROTECT study found the average wearing time to be 11–12 hrs daily, and PREP-2 subscale scores (vision, symptoms, ability to carry out daily activities, and lens overall performance) compared to single vision groups.

Dr Ashley Tuan

Dr Tuan said armed with this evidence, VTI can now “reassure optometrists and parents that nearly all children fitted with NaturalVue will continue to receive a significant treatment effect regardless of the ambient light, even when they are outdoors playing sports or reading, and especially if they are not able to wear sunglasses”.

ABOUT THE CATENARY CURVE

NaturalVue 1 day multifocal has a catenary curvebased design with a rapid and uninterrupted increase in plus power from the optical centre of the lens, which creates a long and narrow extended depth of focus channel along the visual axis. The power profile produces 6-8D of relative plus at 6 mm. The adjusted one-year data from the PROTECT study, taking into account factors that may influence the treatment effect, found that 58% of the cohort had axial length growth similar to normal emmetropic elongation, 45% experienced no change in refractive error over the 12 months, and 64% had no significant change in refractive error (</= 0.25D).

The PROTECT study is a 145-subject, multicentre, double-masked, randomised controlled trial designed to investigate and quantify the safety and effectiveness of NaturalVue Multifocal contact lenses for myopia progression control in children.

References available at mivision.com.au.