This article was originally published in a sponsored newsletter.

Many practitioners may fit soft contact lenses every day without giving on-eye position much thought. Manufacturers have improved lens technology, such that lenses center accurately on the limbus; however, as the pupil is typically decentered with respect to the limbus, the lens optics (e.g., the optic zone) are not typically centered on the pupil. Specifically, in lenses that aim to introduce myopic defocus within the pupil through zonal regions, the amount of defocus introduced may be dependent on where the lens sits relative to the pupil.

Our recent work, presented at the 2023 Annual Meeting of the American Academy of Optometry, describes the on-eye positioning of myopia control soft contact lenses relative to the pupil center and models the impact of lens positioning on the amount and distribution of defocus attained within the pupil.¹

We analyzed aberrometry data from 41 non-diseased right eyes of participants (8 to 32 years of age, mean = 16.4 ± 5.3 years) wearing CooperVision’s MiSight myopia control lenses. Custom software from the Indiana Wavefront Analyzer was used to identify the lens zone geometry and calculate lens center position relative to the pupil center. Repeat measures were acquired at target vergences ranging from 0D to –5D on-axis along the primary line of sight. Participant, model lens, and model eye data were used to calculate the percentage of the pupil that contained myopic, emmetropic, and hyperopic defocus at lens decentrations ranging from 0.6mm temporally to 0.6mm nasally through a 4mm and 6mm pupil.

When viewing on-axis at a distance, contact lenses decentered by a mean of 0.12mm inferiorly (95% CI: 0.08, 0.16) and 0.40mm temporally (95% CI: 0.38, 0.42). Lens position did not significantly change with on-axis viewing distance (p = 0.33). Around 58% of the 6mm pupil was myopically defocused across all measured decentrations. The 4mm pupil was comprised of proportionally more myopic defocus, and dependent on lens decentration. Specifically, when decentered 0.4mm temporally, 74% of the pupil contained myopic defocus compared with 63% when decentered 0.6mm nasally.

These results mirror our previous findings that modern soft contact lenses decenter inferiorly and temporally from the pupil center and suggest that on-eye lens decentration combined with pupil size and lens zone geometry impact the defocus attained within the pupil.² Knowledge of on-eye lens position relative to the pupil center may provide important insight into myopia control zonal lens efficacy, especially given the variability in on-eye lens position.

1. Walther G, Gantest-Nunez J, Richards J, Jaskulski M, Rickert M, Kollbaum P. Optical Effects of Decentering Myopia Control Contact Lenses. 2023. Presented at the 2023 American Academy of Optometry Meeting, New Orleans. Available at aaopt.org/past-meeting-abstract-archives/?SortBy=ArticleAuthor&ArticleType=&ArticleYear=&Title=&Abstract=&Authors=Walther&Affiliation=&PROGRAMNUMBER=. Accessed Nov. 13, 2023.

2. Walther G, Meyer D, Richards J, Rickert M, Kollbaum PS. ON-EYE CENTRATION OF SOFT CONTACT LENSES. Invest Ophthalmol Vis Sci. 2023 Jun;64:1337.