February 1, 2026
By Zeeshan Akhtar, BOptom, MPhil, PhD Candidate at Brien Holden Vision Institute
Photo generated by Gemini
Multisegment design (MS) spectacle lenses have been shown to slow myopia progression in children, but the optical mechanisms underlying this effect remain unclear. Although myopic defocus is often suggested as the main mechanism, reduced image contrast created by these lenses may also contribute to the effectiveness of multi segment lenses. The authors explored whether changes in retinal image contrast, quantified using modulation transfer functions (MTFs), could contribute to the myopia control effect of these lenses.
The authors used optical modelling software (Zemax OpticStudio), to simulate how images are formed in a −4.00D myopic model eye wearing either a single-vision lens or a multi segment lens (Hoya MiYOSMART). Image quality was assessed using MTFs, which describe how well contrast is preserved across different levels of visual detail (spatial frequencies). Three clinically relevant viewing conditions were modelled: straight-ahead viewing through the clear central zone, peripheral viewing through lenslet-covered regions with a stationary eye, and foveal viewing when the eye rotates to look through the lenslet region.
Compared with the clear central zone, viewing through lenslet-covered regions consistently reduced MTF for all spatial frequencies, more significantly at medium and high spatial frequencies. With a stationary eye viewing through the peripheral lenslet region, retinal image quality was substantially degraded, with visual information effectively limited to only a few cycles per degree. MTF declined steeply for peripheral targets in both sagittal and tangential orientations and was slightly better with single-vision lenses than with multisegment lenses. Phase reversal was observed in the sagittal direction at higher spatial frequencies. Although foveal image quality improved when the eye rotated to view through the lenslets, it remained inferior to axial viewing through the clear central zone.
Overall, the findings show that multi segment lenses maintain good central vision while deliberately reducing image contrast in lenslet-covered regions. This suggests that myopia control may depend on low-spatial-frequency signals from the mid-peripheral retina, supporting contrast-based mechanisms rather than defocus alone. This may also explain why different multi segment lens designs show similar clinical effectiveness.
Key takeaway
- Viewing through lenslet-covered regions of multi segment lenses reduces foveal image quality compared with viewing through the clear central zone.
- Lenslets mainly reduce image contrast at medium and high spatial frequencies in both foveal and peripheral vision, compared with single-vision lenses.
- Any myopia-control effect of multi segment lenses is likely driven by low-spatial-frequency information.
Abstract
Myopia Control and Modulation Transfer Functions for Multisegment Spectacle Lenses
Neil Charman, David A. Atchison
Introduction
Multisegment (MS) spectacle lenses, providing a distance correction with a clear central area and by having an array of small, positively powered lenslets in the periphery of the front surface, have proved effective in slowing childhood myopia progression. Debate continues as to whether their mechanism of action is due to through-focus effects or to the image contrast changes due to the inclusion of the lenslets. This study explores the second possibility by modelling the performance of a combined MS lens-eye optical system in terms of its modulation transfer function (MTF) under various conditions.
Methods
The optical design program Ansys Zemax OpticsStudio was used to determine distance MTFs for the combination of either a single-vision or a Hoya MiyoSmart MS lens with a 4 D myopic eye model. Conditions included axial and peripheral objects with co-axial lens and eye, and rotating the eye away from the lens axis to observe objects through the lenslet-covered region of the lens. Visual resolution under each condition was estimated.
Results
Observing objects through the lenslet array lowered modulation transfer in comparison with that given by the single-vision lens, especially as spatial frequency increased. In peripheral observation at a field angle of approximately 32.5 degrees, imagery was poor. Foveal image quality was better with axial viewing through the clear MS lens centre than when the eye was rotated by approximately 30 degrees.
Conclusions
Optimal visual resolution during MS lens wear is achieved when fixating through the clear, central area of the lens. Under these circumstances, objects at 20–50 degrees from fixation are seen through the lenslet-covered region of the carrier which produces a low-pass spatial frequency filtering effect. Here, visual resolution is limited to a few cycles per degree so that any growth control mechanism must rely on low spatial frequency information.
DOI: https://doi.org/10.1111/opo.7001
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Zeeshan Akhtar is a PhD Candidate at Brien Holden Vision Institute supervised by Prof. Arthur Ho and Dr Arthur Back. |
