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Cathleen Fedtke, Ravi Bakaraju; Optical performance modelling of contact lenses used for myopia control. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1755. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Clinical results on visual performance (VP) with myopia control contact lenses have shown inconsistencies between subjective and acuity measures. While MiSight and Proclear Multifocal Distance lenses showed good visual acuity but reduced subjective vision, two novel extended depth-of-focus lenses (EDOF 1 and 2) had significantly better overall vision satisfaction but slightly reduced visual acuity. This work aimed to explain such differences through theoretical modelling of optical performance (OP).
NIMO TR1504 (Belgium) was used to measure the power profiles of the commercial lenses MiSight and Proclear Multifocal Distance (+2.00 add), and two novel extended depth-of-focus lenses (EDOF 1 and 2). The distance label powers of each lens were -1.00, -3.00 and -6.00 D. The best polynomial fits for each lens type were determined from the power profiles. Zemax (OpticStudio 17, US) was used to assess OP. For this, a schematic model eye was defined and the vitreous chamber depth was optimized to achieve eyes with refractive errors of -1.00, -3.00, -6.00 D. A correcting contact lens, designed with the measured power profiles of each lens type, was placed in front of the myopic model eye. OP for various pupils, decentration levels and inherent aberration conditions was computed using the Edge Spread Functions (ESF). The slope and the blur patch size (i.e. background noise) of the ESF were compared.
There were distinctive differences in the ESF between commercial lenses and the EDOF lenses. While the MiSight and the Proclear Multifocal Distance showed a steep slope in the ESF that occurred within the central 10 µm and 20 µm, respectively, the EDOF lenses showed a gradual slope in ESF within the central 40 µm of the retina. While the blur patch sizes of the MiSight and the Proclear Multifocal Distance were about 160 µm, the blur patch sizes of the EDOF lenses were about 90 µm across the central retina. The ESF remained constant with changes in refractive error while some variations were observed with decentration levels and other inherent aberrations.
Conclusions:The slope of the ESF and the size of the blur patch could explain the differences seen between the acuity and subjective VP results between commercial lenses (MiSight, Proclear Multifocal Distance) and the EDOF lenses. The features of the ESF may be used to better optimize the VP of contact lenses.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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