Abstract
Purpose :
Current myopia management spectacle lenses provide static optical cues to slow eye growth, resulting in fluctuating efficacy with time, potentially due to visual cue adaptation. We hypothesize that a dynamic optical signal may be essential to minimise cue adaptation, sustaining efficacy over time. Novel films utilising Spatio-Temporal Optical Phase (S.T.O.P.®) technology were designed and fabricated. Films utilise a plurality of optical elements, featuring azimuthally and/or meridionally varying power distributions, arranged rotationally asymmetric. A change in the orientation of the film, or interchanging films of different designs, provides a dynamic optical signal to the wearer’s eye. This study aims to demonstrate the dynamic nature of S.T.O.P.® film via optical modelling, and in-vitro evaluation and ascertain if the two methods are correlated.
Methods :
OpticStudio (Zemax LLC, USA) was used to model the optical performance of test STOP® films (TF designs: E, F and G) adhered to single-vision lenses, and Stellest® (ST) lenses on a myopic eye. Power profiles of ST lenses were obtained with NIMO (Lambda-X, Nivelles). A custom-built Model Eye (ME) was used to perform the in vitro evaluation. In both methods, a wide-field point spread function (PSF) matrix (±25°) was captured at simulated 25° field angles at 5 azimuthal positions between nasal to temporal, using a 4-mm pupil diameter. PSFs were post-processed through a Fast Fourier Transform to obtain the corresponding modulation transfer function (MTF). Low to medium spatial frequencies (SF) up to 50 cyc/mm were included in the analyses. Dynamic Index (DI) metric, defined as the standard deviation of MTF between the 5 azimuthal positions was calculated at various SFs.
Results :
Optical modelling revealed a higher DI with all 3 TF (DI range: 0.031 to 0.035) compared to ST (DI: 0.018) at both low and medium SFs. Observation of a higher DI with TF compared to ST also held true with the in vitro approach. Using the model eye, DI for TF (DI: 0.085 to 0.139) were approximately 1.5 and 2.5 times greater than that of ST lenses (DI: 0.055).
Conclusions :
Optical modelling and in-vitro ME results demonstrated that all TF have a higher DI than the ST lens demonstrating that S.T.O.P.® optical films provide a spatially and temporally varying optical signal, potentially reducing cue-adaptation. There was good concordance between optical modelling and in vitro methods.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.