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K Kobayashi, K Ohnuma, K Negishi, K Ohno, M Shibutani, G Takeuchi, Y Miyake, T Noda; Prediction of Defocusing Visual Acuity Using Square-Wave MTF in Human Eyes . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2009.
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Purpose: To evaluate the predicted visual acuity (VA) by the square-wave modulation transfer function (MTF) in defocusing measured using a point spread function analysis system (PSFAS). Methods: The clinical VA and the VA predicted from this system were compared in two subjects 24 and 48 years old. The double-pass point spread functions (PSF) of each subject through a 4 mm diameter artificial pupil in defocusing were obtained using a new PSFAS in which a specular reflection double-pass method was used. After calculating the Fourier transform of the double-pass PSF image, we calculated the square root of the modulus to obtain the single-pass MTF, and then the square-wave MTFs were deduced. The predicted VA was determined from the intersection of the square-wave MTF of each defocus position and the modulation threshold measured by Campbell and Green. We measured the clinical VA in each subject with the addition of 0 to 3 diopters by 0.25 diopters of refractive error. Results: A significant correlation was seen between the results of the predicted VAs and the clinical VAs in the two subjects. The correlation coefficients (CC) were follows: CC of 24 years subject was 0.96 in the defocusing range from 0 to 2.0 diopters, 0.99 in the defocusing range from 0 to 1.5 diopters. CC of 48 years subject was 0.93 in the range from 0 to 2.0 diopters, 0.97 in the range from 0 to 1.5 diopters. Conclusion: It was revealed in this study that the single-pass MTFs deduced by PSFAS included the eye’s optical characteristics of the cornea to the entrance of the visual nervous system.
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