The expression of the correction of corneal astigmatism in the point spread function analysis system of human eyes

Abstract

To investigate the ocular optical imaging quality among corneal astigmatism subjects under different corrections by using the Point Spread Function analysis system (PSF). PSF 1000 analyzer was used to measure retinal image quality of eyes of 26 subjects with corneal astigmatism (sphere ranged from -3.00 to -6.00 DS, cylinder ranged from - 0.75 to - 3.00 DC), who were fully corrected with three different methods respectively: spectacles (SPE), rigid gas permeable contact lenses (RGPCL) and toric soft contact lenses (TSCL). The modulation transfer function (MTF) curve was recorded and evaluated. 12 points of the MTF curve (equivalent to the 12 points of Log Mar VA chart) were chosen for analysis. Equivalent moderate myopia 26 subjects without astigmatism were set up as control group. The MTF curve of each eye is enantiomorphous symmetrical. Compared with the control group ( < -0.75D), with 3.0 mm pupil, there's no statistical difference under low spatial frequency, the difference between middle and high frequency is significant (P < 0.05). With 6.0 mm pupil, there is statistical difference in all frequencies (P <0.01). With simulated 3.0 mm pupil and 6.0 mm pupil, MTF values of all these three methods are statistical different. With 3.0 mm pupil, the MTF value of eyes fitted with RGPCLs is higher than that fitted with TSCLs except in the following frequency 3.00, 3.78, 4.78, 30.00 and 37.80 c/deg (P <0.05). With 6.0 mm pupil, the three correction methods are statistical different in all frequencies (P <0.05). In all these three methods, MTF values with simulated 3.0 mm pupil are significantly higher than that with simulated 6.0 mm pupil (P <0.01). PSF analytical method is available for offering objective data of retina imaging quality. RGPCL and its induced tear film is improved not only correcting the corneal astigmatism, but also enhances the ocular optical quality by reducing diffraction, dispersion and other high order of aberration.