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Augustine Nyarko Nti, Gareth D Hastings, Jason D Marsack, Eric R Ritchey, David A Berntsen; Spherical aberration in center-distance multifocal soft contact lenses as a function of power and pupil size. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6374.
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© ARVO (1962-2015); The Authors (2016-present)
Center-distance soft multifocal contact lenses (MFCL) are currently used for myopia control. Spherical aberration (SA) influences the amount of myopic retinal defocus. The amount of SA observed in three commercially available center-distance MFCLs across a range of powers and analysis diameters was determined.
Biofinity Multifocal “D” +2.50 add, Proclear Multifocal “D” +2.50 add, and NaturalVue Multifocal were studied. For each MFCL brand, two lenses of each power ranging from -1.00 to -6.00D in 1D steps were stored in phosphate buffered saline (PBS) conforming to ISO 18369-3:2017 standards for 24 hours prior to measurement. Aberrations for each MFCL were measured in a PBS filled wet cell with the SHSOphthalmic aberrometer using auto edge detection mode. Center thickness, as measured by the Ivue OCT, and manufacturer-reported material refractive indices were utilized in aberration calculations. Aberrations were rescaled to various diameters for analysis (3mm, 4mm, 5mm, and 6mm). A repeated-measures ANCOVA was used to determine the effects of lens brand, analysis diameter, and lens power on SA.
Increases in SA as analysis diameter increased differed by lens brand (analysis diameter x brand; p < 0.0001). For a 3mm analysis diameter, mean SA (±SD) across all lens powers were +0.031 ± 0.003 µm (Biofinity D), +0.040 ± 0.003µm (Proclear D) and +0.086 ± 0.001 µm (NaturalVue). SA at a 5mm analysis diameter was +0.168 ± 0.024 µm (Biofinity D), +0.217 ± 0.019 µm (Proclear D), and +0.361 ± 0.014 µm (NaturalVue). With increasing diameter, SA increased more rapidly for the NaturalVue lens than the other two lenses. This is consistent with manufacturer reported lens designs in which increases in plus power begin much closer to the optical center with the NaturalVue lens than with the other two lenses. For a 6mm analysis diameter, SA was less positive as lens power became more negative for all three lens brands measured (Biofinity D β = 0.025 µm/D; Proclear D β = 0.016 µm/D; NaturalVue β = 0.026 µm/D; all p ≤ 0.008).
As analysis diameter increases, there are differences between lens brands in how quickly SA increases. At a 6mm analysis diameter, all three center-distance MFCLs had positive SA that decreased slightly as minus power increased. Further work is needed to understand the effect of SA on visual performance with these lenses under different pupil sizes.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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