Abstract
Purpose :
To fill the gap in independently published information, this work presents a measurement method and results of sag maps of optical sub-elements (OSE) of two established (Stellest, SL, Essilor, USA and MiyoSmart, DIMS, Hoya, USA) and a novel P.A.U.S.E.® (Phase Alteration Utilising Sub Elements) myopia management spectacle lenses.
Methods :
A novel, custom-built instrument was developed (PLENTIPlus, nthalmic, AU) to automate the measurement of sag profiles of OSE utilizing principles of white light interferometry. The instrument was validated using a step height standard of 9.187 µm. Repeatability of peak sag values was determined through 5 repeated measures of the same OSE of SL lenses. OSEs at 3 locations from SL and DIMS lenses, as well as from P.A.U.S.E.® lenses characterized with extended depth of focus (EDOF) OSE (consisting of 5 different types, two each from two different lenses) were measured and analyzed. OSE sag maps were obtained by subtracting the base curves of the spectacle lenses. From these sag maps, two perpendicular cross-sectional sag profiles were taken, and peak sag values were determined.
Results :
Step height accuracy was measured as 9.128 µm, 0.059 µm different from nominal. Repeatability of the SL OSE was within a range of 0.03 µm. No difference in peak sag was found between the 3 locations and between the two perpendicular meridians for the SL and DIMS OSEs. Mean peak sag for SL is 1.17±0.09 µm and 0.87±0.05 µm for DIMS, significantly different (p<0.005). OSEs from EDOF included two types of modified light swords (mLS1 and mLS2) and three types of modified axicons (mA1 to mA3) with peak sag values ranging from 1.60 to 2.00 µm. Their measured differences from the target peak sag were 0.09±0.09 µm for mLS1, 0.03±0.13 µm for mLS2, 0.18±0.18 µm for mA1, 0.09±0.09 µm for mA2 and 0.02±0.12 µm for mA3. All the EDOF OSEs peak sag values are significantly higher than both the SL and DIMS (p<0.005).
Conclusions :
A viable instrument was developed to quantify the sag profiles of various types of OSEs. Manufacturing consistency appears to be good for all three lens types. Distinct differences in peak sag were found between SL, DIMS and EDOF OSEs, which may be attributed to their specific design intent characteristics. Employing these sag maps in optical modelling routines could potentially help in interpreting the differences in clinical visual performance.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.