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Eon Kim, Ravi Bakaraju; Through-focus retinal image quality of commercial multifocal contact lenses. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1758. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the optical performance and its dependence on pupil size and aberrations, of commercially available multifocal contact lenses (MFCLs) using through-focus retinal image quality (TFRIQ) metric defined as visual Strehl ratio.
Power profiles of 9 lens types grouped as center-near (CN), center-distance (CD) and concentric (BF)] were measured using NIMO TR1504 and modelled in conjunction with presbyopic schematic eyes using proprietary software written on Matlab® and Zemax® platforms. TFRIQ values were computed over target vergences, ranging from -0.5 D to 2.00 D, for five different pupil sizes (3 mm, 4 mm and 5 mm) and three different inherent aberration levels. A log transformation was applied to the TFRIQ values to enhance the differences between the lens types.
General shapes of the TFRIQ curves were preserved across pupils and aberration models for most lens types. The performance of CD and CN lens types were pupil-dependent. The smaller the pupil, the better the performance for near with CN lens type. The opposite was observed with CD lens type. For most CN lenses, performance peaked around 0.50 D and gradually worsened towards +2.00D vergence. Proclear Near design was an exception for which the peak performance shifted towards +1.50D for 3.00 mm pupil. However, the RIQ remained very low across all vergences for larger pupils. Air Optix MF demonstrated a balanced TFRIQ curve spanning wide range of vergences. Proclear D produced RIQ values which peaked at distance vergence and gradually worsened towards near. The effective multifocality was appreciated at pupils > 4 mm. The concentric lens types produced distinct peaks in the TFRIQ curves, highlighting bifocality in performance. Performance of concentric BFs was observed to be relatively insensitive to variations in the inherent ocular aberrations when compared to the CD and CN lens types.
The TFRIQ curves demonstrate a ‘see-saw’ effect with the CD and CN lens types. The greater the performance at near, the poorer the performance at the distance. This is largely a function of the pupil size. On the other hand, the TFRIQ curves of concentric lens types demonstrate bifocality i.e. performance for intermediate vergence lies in a trough. The CD and CN designs are more sensitive to variations in inherent aberration compared to BF type.
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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