Abstract
Purpose :
Several types of spectacle lenses are currently used for myopia control (MC). However, their chromatic imaging properties have not been evaluated. In this context, we recorded and processed the point spread function (PSF) of three MC spectacle lenses and a single-vision lens at different eccentricities and three illumination colors (red, green and blue).
Methods :
Four lenses (base power, +2D) were tested: (1) MiYOSMART, Hoya; (2) Stellest, Essilor; (3) SightGlass, CooperVision; (4) a single-vision lens, Carl Zeiss Vision. We adapted an instrument based on spatial light modulation technology (Arias et al., Optica, 2023) to record defocused PSFs through the spectacle lenses being illuminated with three coaxial beams (wavelengths, 450, 532 and 635 nm) at three temporal eccentricities (0, 20 and 30°) along the horizontal meridian. The pupil (radius, 4 mm) was shaped according to eccentricity. The through-focus area under the modulation transfer function (TF-AUMTF) was calculated from the PSFs as an image quality descriptor. The longitudinal chromatic aberration (LCA) was estimated as the focus difference for blue and red.
Results :
AUMTF decreases with the wavelength because of diffraction. All lenses exhibit similar LCA (-0.80 ± 0.06 D) across the eccentricities. Lenses (1) and (2) led asymmetric TF-AUMTF around their best focal positions. The ratio of the sum of myopic (defocus, from 1 to 4 D) and hyperopic (defocus, from -4 to -1 D) AUMTF values are: 1.2 at red, 1.2 at green, and 1.1 at blue for lens (1); and 0.9 at red, 0.8 at green, and 0.7 at blue for lens (2). The power of lenslets in those lenses depends on the wavelength. Conversely, TF-AUMTF is symmetric in lenses (3) and (4), being slightly higher – up to 2.5 times – in lens (3) than lens (4) at defocus higher than 0.65, 0.75 and 0.9 D around the best focus at red, green and blue, respectively.
Conclusions :
Blue illumination enhances the image quality of stimuli generated through the MC spectacle lens. However, the impact of such enhancement on retinal stimulation could be limited since the eye's photopic spectral sensitivity is maximized at green. The higher myopic AUMTF values in lens (1) than in lens (2) are explained by the lower power and higher fill factor of the lenslet array in lens (1) than in lens (2). Characterizing MC spectacles with polychromatic light can provide helpful cues to optimize their clinical efficacy.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.