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G.–Y. Yoon, T. Jeong; Effect of Dynamic Movement of Customized Contact Lens on Visual Benefit of Correcting Higher Order Aberrations in Keratoconic Eyes . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2051.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Dynamic movement of customized contact lens after blinks is one of the factors that reduces visual benefit of correcting higher order aberrations in the eye. The goal of this study is to theoretically investigate the feasibility of improving vision with customized contact lenses in keratoconic eyes when dynamic decentration and rotation of customized contact lens are taken into account. Methods: Wavefront aberrations of fifteen keratoconic eyes were measured with the large dynamic range Shack–Hartmann wavefront sensor. With the measured wavefront aberration, modulation transfer functions under the white light condition were calculated to estimate visual benefit. Visual benefit was defined as the ratio of the volume under the modulation transfer functions (vMTF) with second and higher order correction to that with second order correction only. Visual benefit was also calculated with dynamic decentration and rotation of customized contact lens. To simulate this dynamic movement, Monte–Carlo method was used to combine dynamic decentration and rotation of customized contact lens weighted by Gaussian distribution. The same analysis was performed in 30 normal eyes for comparison. Results: When perfectly correcting higher order aberrations with customized contact lens, keratoconic eyes experienced the visual benefit of 4.4 ± 2.0 for a 6 mm pupil. This visual benefit is approximately 2 times larger than that obtained in normal eyes. When considering the dynamic movement of customized optics, the visual benefit in keratoconic eyes was decreased to 1.5 ± 0.2 with the standard deviations of 300 µm decentration and 7 degree rotation in Gaussian distribution which covers a range of ±600 µm and ±14 degree, respectively. On the other hand, normal eyes experienced 1.3 ± 0.1 with the same amount of contact lens movement. Visual benefit in keratoconic eyes was reduced more largely with an increase in the amount of lens movement compared to that in normal eyes. Conclusions: Correcting higher order aberrations in keratoconic eyes provides larger visual benefit than in normal eyes. Visual benefit for keratoconic eyes is more sensitive to decentration and rotation of customized optics compared to the normal eyes. Our calculation demonstrates that correcting higher order aberration with customized optics improves retinal image quality even with the dynamic movement of customized contact lens although actual perceived vision improvement needs to be evaluated.
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