Study Of Wavefront Aberrations On Eyes Of Refractive Error In Chinese Children

【Objective】To investigate the distribution of ocular and corneal high-order aberrations(HOAs, 3^rd to 6^th orders) in eyes of school children,by using the iTrace Visual Function Analyzer,and study the changes as a function of the degree of myopia and to investigate the influence of refractive error and cycloplegia.【Methods】Wavefront aberrations were measured using the iTrace Visual Function Analyzer in 114 eyes of cyclopleged school children,with106 of these eyes also undergoing corneal topography measurements.Root mean square(RMS) of total HOAs,3^rd-,4^th-,5^th-,6^th-order aberrations,and coma(Z₄⁰,Z₆⁰),SA(Z₃^-1, Z₃¹,Z₅^-1,Z₅¹ ) of the ocular,corneal,and internal aberrations were computed from the central 6.0mm and 4.0mm zone.Correlation analysis was performed to assess the association between HOAs and refractive power,HOAs and pupilar diameter.Aberrometry was also conducted on a subgroup of 36 eyes,both before and after cycloplegia to investigate the effect of paralysis of accommodation. Compensation factor(CF) was computed to assess how internal optics compensate for anterior corneal aberration.【Results】1.The mean of the ocular and corneal total high order RMS(3^rd to 6^th) was 0.505±0.227μm and -0.147±0.796μm respectively(pupilar diameter=6mm).The values of high order RMS progressively decreased from the 3^rd-order to the 6^th-order.2.Subjects with low myopia showed less positive levels of spherical aberration than other refractive error groups.No correlation was found between total ocular high order RMS and myopia(p=0.184) as well as SAs.High correlation was found between total corneal high order RMS and hyperopia(pupilar diameter=6mm).3.The total ocular high order RMS values at least doubled for 83.3%subjects when the pupil dilates from 4 to 6mm.For dilated pupils,the linear regression between aberration and myopia is similar.4.After cycloplegia,a statistically significant increase was observed in spheric equivalent and in mean RMS values of total-,third-,fourth-,fifth- and sixth-order aberrations(p＜0.05).5.The CFs varied widely among subjects.The negative values of internal SA compensated for the positive SA of comea.For eyes with low whole-eye RMS values,mean RMS for the anterior cornea was greater than that for the whole eye. However,for eyes with larger whole-eye RMS values,the RMS values of the anterior comea were less than that for the whole eye.Intemal optics made important contributions to the wave-front aberrations for higher-order aberrations. in the whole eye【Conclusions】1.The values of high order RMS progressively decreased from the 3^rd-order to the 6^th-order(pupilar diameter=6mm).2.Subjects with low myopia showed less positive levels of spherical aberration than other refractive error groups.No correlation was found between total ocular high order RMS and myopia as well as SAs.3.The total ocular high order RMS values at least doubled for 83.3%subjects when the pupil dilates from 4 to 6mm.4.After cycloplegia,a statistically significant increase was observed in spheric equivalent and in mean RMS values of total-,third-,fourth-,fifth- and sixth-order aberrations(p＜0.05).5.Internal surfaces compensated at least partially for the HOA and Z₄⁰ in most eyes.