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Ravi C. Bakaraju, Klaus Ehrmann, Darrin Falk, Arthur Ho, Eric B. Papas; Evaluating Optical Performance of Presbyopic Contact Lenses via a Single-Pass Method. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6482.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate in vitro optical performance of several commercial multifocal contact lenses (MFCL) using an anatomically and optically equivalent model eye (ME).
The developed ME is capable of changing accommodative and refractive states, pupil size, and can be fitted with soft CLs to investigate their optical performances. The instrument was configured to simulate presbyopia with an axial refractive error, and was corrected with seven appropriate MFCLs with high and low-add powers, and a single vision control. Optical performance was evaluated at 3 pupils, 7 target vergences, and 5 different CL positions, via 2 input channels: 1) spatially filtered, monochromatic (632.8 nm) collimated beam, and 2) visual acuity charts (VAC). The active photo sensor situated at the retinal plane facilitated retrieval of single-pass (SP) information. Channel 1 was used to compute visual Strehl ratio (VSOTF) measures, while channel 2 yielded images casted of VAC objects. Centration of CLs was monitored by an integrated tracking camera.
Overall, most MFCLs demonstrated a reduced peak performance for distance and considerable levels of through-focus performance relative to single vision control. Proclear (D) produced best through-focus VSOTF performance. Proclear (N) outperformed the rest for near. AirOptix demonstrated good performance at intermediate and far vergences. Purevision and Acuvue showed through-focus performances comparable to the rest, but only for pupils ≥4mm. Acuvue Oasys produced performance comparable to single vision control. Decentration of MFCLs demonstrated a substantial effect on the through-focus performance. None of the designs were free of haloes and ghosting. Ghosting effects were prominent for small pupils, where halos were minimal. At 4mm pupil, both ghosting and haloes became prominent. For pupils >4mm, halo effects dominated ghosting. In well-centered positions, center-distant designs produced ghosting at near, while center-near type demonstrated ghosting for intermediate and far. Reverse occurred when CLs were deliberately decentered. These observations were consistently true with both high and low add powers.
Novel result of this work is the direct acquisition of SP images obtained when MFCLs are used in conjunction with the developed instrument. We evaluated performance across several designs on an identical platform that employed a consistent and repeatable approach, thus offering original insight and progress in the field.
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