Abstract
Purpose :
Lenslet (spherical powered optical elements) and ring (cylindrical powered optical elements) based spectacle lens designs have been demonstrated to be effective in myopia control clinical trials. We aim to characterise the power distribution of the myopia control features of four commercially available spectacle lenses.
Methods :
Two lenslet array (MiyosmartTM Hoya, Japan, StellestTM Essilor, France) and two ring array (MyocareTM Zeiss, Germany and iBrightTM Eyebright, China) spectacle lens designs in base powers –1.00 D to –5.00 D (1.00 D steps) were measured. Optical powers of spectacle lenses were measured using NIMO TR1504 (Lambda-X), an instrument based on Hartmann-Shack principle and Phase-Shifting Schlieren technique. The powers of the treatment zones were measured using two modes in NIMO: (i) Area scan - spherical equivalent power (SE) at each pixel is radially averaged over the zone of interest (Fig. 1A/1B); and (ii) Line scan - SE measured across a linear cross-section of the lens (Fig. 1C/1D).
Results :
The average additional SE at each lenslet/ring are plotted in Fig 2. In area scan mode: lenslets showed a peak positive power in the centre which gradually decreased to the edge of the lenslet; rings exhibited cylindrical pattern with the most positive cylinder axis aligned with the circumference of the rings. In line scan mode: both ring and lenslet based lenses showed a higher peak positive power than from the area scan mode that also rapidly decreased in peak positive power from the centre of lenslet/ring.
Conclusions :
Treatment zone SE measured by line scans were significantly more positive than area scans, especially for rings due to their cylindrical optics. Whether the treatment zone SE or most positive power meridian of the cylindrical element is more relevant for myopia control needs exploration.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.