Effect Of Wave Aberration On Optical Quality Of Myopia

Objective:i-trace vision analysis were used to investigate the effect of modulation transfer function (MTF) on the optical quality and the relationship between the different wavefront aberration, in order to give basically theory to the refractive surgery.Methods:Wavefront aberration of the 100 cases (100 eyes) myopia patients were measured by i-Trace visual function analyzer. Tropicamide Phenylephrine Eye Drops were used to diameter the pupil to be scattered to the pupil diameter is 6 mm, i-trace visual function analyzer scanning set to 6 mm diameter, checking the right eye of patients,measured three times in a row, excluding points more than 10 times. Statistics of the high-order aberration, low order aberrations, defocus, astigmatism, spherical aberration, coma and trefoil aberration under the 6 mm diameter of pupil. Using Zernike polynomial describe the wavefront aberration。A total of 44 order and 7 items of Zernike polynomial were measured. Z2-Z5 for the low-order aberration; Z6-Z44 for the higher-order aberration; Z3 (C2-2), Z5 (C22)for the astigmatism; focus Z4(C20); Spherical aberration Z12 (C40); coma Z7(C3-1)、Z8(C31)microcomputer) and trofoil aberration Z6(C3-3)、Z9(C33). Analysis MTF curve of total aberration, lower aberration, higher aberration, astigmatism, defocus, spherical aberration, coma and trefoil. Compare the mean MTF curve and the mean height of MTF curve. Then select 10 myopia patients, Using Zemax software to establish a personalized model eye according to the actual measured of the radius of corneal curvature, anterior chamber depth, cornea thickness, crystal thickness, the thickness of the vitreous parameters,based on the Gullstrand-Le Grand eye mode. Then optimize the matrix of lens aperture size, thickness, surface anterior and posterior surface design. Comparing the MTF curve s after the SMILE surgery between the traditional method and use personalized model design.Result:Under the 6mm optical area, the mean total aberration, lower aberration, higher aberration, astigmatism, defocus, spherical aberration, coma and trefoil are (5.047±3.041) um、(0.349±0.295)um、(5.060±3.354)、(0.410±0.288)um、 (5.031±3.362)um、(0.307±0.306) um、(0.094±0.075)um、(0.172±0.148) um. There were negatively correlated between different wave front aberration and average height of MTF curve when its exist alone. The average height of MTF curve of total aberration exist alone were higher than low order aberrations exist alone (t=2.548, P <0.05). The average height of MTF curve of spherical aberration exist alone were higher than coma aberrations exist alone.Conclusion:These results support the idea that the eye’s wave aberrations re interdependent in ways that improve the eye’s MTF. We should pay more attention to the correction of low order aberration, also requires as much as possible to reduce the high order aberration, in the smile surgery, make the low order aberrations and higher-order aberrations to achieve a balance, thus improve the patients postoperative visual quality.