The Effect Of The Degree Of Astigmatism On Visual Quality Of Children

Objective More and more evidence has revealed that astigmatism caused by the different curvature of two orthogonal meridians is one of the leading causes of reduced visual acuity among children.Amblyopia resulting from astigmatism can further reduce visual performance,such as contrast sensitivity,visual acuity.It is very important to investigate the effect of astigmatism so that we can make measures to correct it.The effect of the degree of astigmatism on visual quality of children,including the root mean square(RMS)of the high-order aberrations,modulation transfer function(MTF)and point spread function(PSF)is of vital importance.It is helpful to understand the influence factors of children's visual development,so as to guide the clinical application.Methods We analyzed the clinical characteristics of the children who came to the Pediatrics department of Ophthalmology Center,the Second Affiliated Hospital of Dalian Medical University.The children,ranging in age from 7 to 10 years,were dilated the pupils with 1% atropine ointment for three days,performing optometry examination.One hundred and eighteen children who met the inclusion criteria were divided into three groups according to the degree of astigmatism: group A,with astigmatism greater than or equal to 1.0D and less than 2.0D;group B,with astigmatism greater than or equal to 2.0D and less than 3.0D;group C,with astigmatism greater than or equal to 3.0D and less than 4.0D.In the meantime,OPD-SCAN-III aberrometer was used to measure corneal topography,point spread function(PSF),modulation transfer function(MTF)and other optical images.Totalhigher order aberrations,total coma aberration,total spherical aberration,total trefoil aberration corresponding to the RMS value and the AR(Area ratio)value of MTF,the SR(Strehl ratio)value of PSF with a 4mm pupil diameter were assessed.Three groups of higher order aberrations corresponding to the RMS value and the AR value of MTF,the SR value of PSF were respectively compared by one-way ANOVA.Results Statistical analysis was performed using SPSS version 17 Statistical Software for Windows(SPSS Inc,Chicago,IL,USA).Results are expressed as the mean ± standard deviation.The results(RMS-HO?RMS-T.Sph?RMS-T.Coma?RMS-T.Tre,the AR Values,the SR Values)are in accord with the normal distribution.There was no significant difference in clinical data such as age,gender,spherical equivalent refraction and other indicators among three groups.Three groups of RMS-HO(the RMS of total higher order aberrations)?RMS-T.Coma(the RMS of total coma aberrations)? RMS-T.Tre(the RMS of total trefoil aberrations)and RMS-T.Sph(the RMS of total spherical aberrations)significantly increased with the degree of astigmatism increasing.While there were no significant differences in RMS-T.Sph of groups.The AR value and the SR value decreased with the degree of astigmatism increasing.And there were significant differences in the AR value and in the SR value.Conclusion The RMS of higher order aberrations increased with the degree of astigmatism increasing in the children with-the-rule astigmatism,then declining the visual quality.And the increase of total coma aberrations is the most obvious among higher order aberrations.The AR value and the SR value decreased with the degree of astigmatism increasing,thus declining the visual quality.Astigmatism has a significant influence on the higher-order aberrations,MTF and PSF in the children with-the-rule astigmatism.These three parameters are of great significance to evaluate visual quality objectively.