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Cathleen Fedtke, Klaus Ehrmann, Varghese Thomas, Ravi Chandra Bakaraju; Impact of primary and secondary spherical aberrations of multifocal soft contact lenses on vision. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1494.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the impact of the primary (PSA) and secondary (SSA) spherical aberration terms, as measured with commercial bi-/multifocal (MFCL) soft contact lenses on eye, on visual performance (VP).
Seventeen presbyopes (age: 55.1±6.9 years) wore 7 commercial study lenses (4 center-near (MFCL N), 1 center-distance (MFCL D), 1 bifocal (BF) and 1 single vision (SV) control) binocularly for up to 1 hour. At baseline (unaided) and with each lens on eye, the PSA and SSA terms were measured with the BHVI-EyeMapper (low illumination). High- and low-contrast distance visual acuity, contrast sensitivity, high-contrast visual acuities at intermediate and near, and range of clear vision were measured. In addition, subjective VP variables included clarity of vision at distance, intermediate and near, ghosting at distance and near, and overall vision satisfaction. Linear mixed model was used to compare lens groups for the PSA and SSA terms. Pearson’s correlation (PC) was used to determine the association between the PSA and SSA terms and the VP variables.
PSA was significantly (p<0.05) more negative with the MFCL N (mean PSA=-0.053±0.080µm) and BF (PSA=0.005±0.067µm) lenses and more positive with the MFCL D lens (PSA=0.208±0.160µm), compared to the control (0.067±0.072µm). Conversely, SSA was significantly more positive for the MFCL N lenses (mean SSA=0.025±0.029µm) and, although not significant, more negative for the MFCL D lens (SSA=-0.018±0.023µm), compared to the control (SSA=-0.001±0.017µm). PSA and SSA terms were significantly (p<0.05) correlated to 77% and 46% of VP variables, respectively, however the PC coefficients were weak, i.e. ranging between |0.210| to |0.334|. While distance variables showed improved VP with more positive PSA or negative SSA, most intermediate/near variables showed improved VP with more negative PSA and ghosting at near was improved with more positive SSA terms. Range of clear focus was better for more negative PSA terms.
The amount and direction of PSA and SSA, as measured with the different MFCLs on eye, can affect VP at different distances. Results of this study may provide useful information when aiming to design new MFCLs for improved visual performance at certain distances.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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