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Ravi C Bakaraju, Cathleen Fedtke, Klaus Ehrmann, Darrin Falk, Jiyoon Chung, Arthur Ho, Brien A Holden; Accommodation error with single vision, bifocal and multifocal soft commercial contact lenses.. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3760.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the accommodative error (AE) when young myopic adults are fitted with different types of single vision (SV), bifocal (BF) and multifocal (MF) commercial contact lenses (CL) in a monocular viewing condition.
On-axis ocular wavefronts of forty myopic participants (24.2 years ± 4.2, 65% Female, Spherical equivalent: -0.50 to -4.50D) were measured using the EyeMapper, a global aberrometer, when corrected unilaterally, one at a time, with: six SVCLs [AirOptix Aqua®, Proclear®, Acuvue Oasys®, Biofinity®, Clariti®, Focus Night & Day®]; three BFCLs [Acuvue® +1.50D & +2.50D add powers, Misight®]; and eight MFCLs [AirOptix Aqua® and Purevision® in low & high adds, Proclear® D & N in +1.50D & +2.50D adds]; at two object vergences: +1.00D (fogging state) and -3.00D accommodative demand. Each wavefront obtained as a 10th order Zernike polynomial (over a natural pupil size) was post-processed to obtain through-focus retinal image quality (TFRIQ) measures. Difference between the stimulus vergence and optimum defocus (in combination with the wavefront) required to maximize retinal image quality (RIQ) metric was defined as AE. Non-iterative methods such as least-square Zernike (2nd order) and Seidel or paraxial curvature-matching techniques (both 4th & 6th order) were also used to compute the AE.
The magnitudes of the peaks of TFRIQ obtained with the SV correction were twice of those obtained with the high add BF/MFCLs. At 3D vergence, almost all the SV lenses produced optimal accommodative response when gauged via the Seidel method, however small amounts of lag (up to 0.50D) were observed when Zernike and iterative RIQ methods were considered. The Proclear D MF produced optimal responses with the iterative RIQ method but showed significant amounts of lag with Seidel technique; the reverse was observed with Proclear N, AirOptix and Purevision MFs, which held true for both high and low adds.
The AE measures obtained with the test lenses differed vastly with the method of calculation. This can be attributed primarily to interactions between the spherical aberration of the lens, the aberration of the accommodating eye, imposed defocus or combinations thereof. The AE obtained with the iterative RIQ methods were much small in magnitude for all test lenses with an exception of Proclear N.
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