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Pablo De Gracia, Andreas Hartwig; Optimization of the Kamra inlay for a large population of subjects. Invest. Ophthalmol. Vis. Sci. 2017;58(8):327.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the multifocal properties of the Kamra inlay (Acufocus) in 1299 healthy subjects by using the visual Strehl ratio (VSOTF) metric. Also, to explore how different inner and outer radius of the inlay would modify the properties of the design.
The optical properties of the Kamra inlay were analyzed by computing the VSOTF metric through-focus (-1 to 5 D). The simulations included the variation of the inner (1-2.5 mm) and the outer diameters (3.0 - 5.0 mm) of the KAMRA inlay for an ideal eye with varying pupil sizes (1 to 8 mm). The Kamra inlay has 8400 holes with a diameter varying between 6 and 12 µm. The area covered by the holes roughly represents a 4% of the circular area covered by the corneal inlay. The representation of the Kamra Inlay in our calculations was performed by introducing an apodization effect (six levels: 80 - 84 - 88 - 92 – 96 -100 %) on the generalized pupil for the circular area defined by the inner and outer radius of the inlay. The current design, and the three best solutions found in the simulations with the ideal eye were recalculated. This time, introducing the Higher Order Aberrations of the 1299 subjects on this study. Finally the resulting VSOTF’s were evaluated both under monocular and binocular conditions according to three values: the area under the VSOTF, the range through focus of acceptable optical performance, and, for binocular combinations, the optical disparity occurring between left and right eyes.
The average optimal solution for our population of subjects has an inner radius of 2 mm and an optimal outer radius of 4 mm. These values improve the area under the VSOTF by 4% and the range through focus by 7%. The apodization variable - that corresponds to different amounts of wholes in the inlay – showed a direct correlation with the optical performance of the design; the higher the apodization the higher were the optical performance of the inlays.
A slightly larger central aperture would improve the optical properties of the Kamra inlay. Also, the holes in the corneal inlay - that are necessary to allow the proper transmission of nutrients between layers of the cornea and therefore to preserve its integrity - have to be minimized in order to increase the optical properties of the Kamra inlay. The optical properties of the inlay improve by decreasing the area occupied by holes on the design.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Figure 1. Functioning of the Kamra inlay.
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