Abstract
Purpose :
An increasing variety of myopia control spectacle lens (MCSL) designs are emerging. However their optical features potentially create distortion in the field of view affecting tolerance and compliance. The aim was to develop a novel bench device to measure this distortion and evaluate commercially available MCSLs.
Methods :
An opto-electro-mechanical Lens Distortion Tester (LDT) was developed for evaluating Static Field (SF) and Horizontal Smooth Pursuit (HSP) distortion. The LDT includes a colour camera with a focusing lens, a test lens mount on an automatic pivoting arm, and a monitor to present a target object. The LDT can resolve micro to macro levels of distortion by adapting the optical layout.
Targets were black and white linear gratings in a range of spatial frequencies. Custom software controlled a pivoting arm for transverse angular lens movements to capture a sequence of output images. Post-processing analysis software was developed in Matlab whereby edge detection and deviation due to distortion was quantified by decomposition into frequency components.
Four commercially available spectacle lenses were evaluated; Hoya Single Vision (SV), Zeiss MyoVision, Hoya Miyosmart, and Essilor Stellest. Output of the distorted target edge was assessed using histogram plots. The frequency and magnitude of distortion was quantified across the field of view.
Results :
The results presented in Fig.1 & 2 suggest consistent trends between SF and HSP:
— SV had the least amount of distortion spread evenly across the field, as represented by low magnitudes for all frequencies.
— MyoVision had the largest amount of low frequency (blue) distortion which increased to the peripheral field (i.e. peripheral drift).
— Miyosmart had a medium amount of distortion spread evenly across the field shown by low-medium (light blue) and medium (orange) frequencies (i.e. small jitter) in SF and HSP respectively.
— Stellest had a large amount of distortion increasing to the peripheral field with medium (orange) and low-high (light blue to green) frequencies (i.e. large jitter) in SF and HSP respectively.
Conclusions :
The LDT can distinguish distortion characteristics between the various MCSL technologies. Each MCSL technology type (progressive power and lenslet) offers differing qualities and amounts of distortion. Miyosmart lenslets create the least distortion magnitude and change across the field of view when compared to other MCSL types.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.