The Clinical Research On The Morphological And Optical Effects In Cornea With Orthokeratology

PURPOSETo investigate the dynamic changes of corneal morphology and optical characteristics with orthokeratology applying in one-year follow-up.To evaluate optic characteristics by Fourier analysis with orthokeratology applying.METHODSThere were 20 patients(40 eyes)with low-moderate myopia selected in this clinical research with orthokeratology applied in the First Affiliated Hospital of Zhejiang University,whose first visiting time were from July to December in 2015.The average age was 13.1±2.86 years,ranging from 8?20,and the average spherical equivalent refraction was-2.94±0.94D.Ophthalmological examination was executed to exclude eye disease and contraindications of contact lens.All patients were applied with orthokeratology and follow-up visited at pre-wear,1 day,1 week,1 month,3 months,6 months and 12 months after orthokeratology.In every visit,record uncorrected visual acuity and subjective optometry result,record mean diopter,astigmatism and Q-value of front and back cornea surface,and record cornea apex thickness,thinnest thickness and thinnest location from Pentacam anterior segment analysis system.Record the Fourier analysis result of spherical index,asymmetry,regular astigmatism and higher order.SPSS 22.0 statistic software was used for statistics and p<0.05 was thought to be of significance.RESULTS1.The changes of uncorrected visual acuity and spherical equivalent were of significance(p<0.001).Compared with pre-wear,uncorrected visual acuity increased(p<0.001)and spherical equivalent decreased significantly(p<0.001)especially within 1 week(p<0.001).2.The changes of the mean diopter and Q-value of front cornea surface were of significance(p<0.001)but the change of corneal astigmatism was not(p>0.05).Compared with pre-wear,the mean diopter of front cornea surface of all follow-up times decreased significantly(p<0.001);Q-value also increased(p<0.001)to the maximum in 1 month but also decreased till 12 month-follow-up(p>0.05).The mean diopter,the astigmatism and Q-value of back cornea surface were all of no significance(p>0.05).The differences of the apex thicknesses of cornea were of no statistic significance(p>0.05).Neither did the thinnest thicknesses and the distances from thinnest location to apex were of no significance(p>0.05).3.Fourier Analysis:Compared with pre-wear,the spherical minimal radius increased(p<0.001),the eccentricity decreased(p<0.001),the maximal decentration increased(p<0.001)for the continuity of first 1 month;the central regular astigmatism increased significantly(p<0.05)except 1 week-follow-up,and the peripheral regular astigmatism increased significantly(p<0.05),too,except 1 day-follow-up;High order of irregularity also increased significantly(p<0.05)except 1 day-follow-up(p>0.05).CONCLUSIONS1.Refractive correction of myopia is related with flatting of the front surface of cornea to reduce corneal diopter of front surface especially in first month.The back surfaces,thickness of cornea and thinnest location have no significant change.2.The change of Fourier 0,1,2 and high order parameters are all significant,especially in first month.Fourier analysis is one of effective way to describe the optical change of cornea.