| IntroductionOrthokeratolgy is a specially designed rigid gas permeable contact lens that reshapes the cornea by exerting pressure on the cornea,temporarily changes the curvature of the cornea to correct refractive error,and improves uncorrected visual acuity.This study analyzed and compared the changes of corneal endothelium,axial length and choroid in myopic children wearing single vision distance spectacles and OK lenses.To help us have a deeper understanding of the mechanism of orthokeratology.ObjectiveTo analyze the effects of orthokeratology on corneal endothelial cells,axial length,choroid thickness and blood flow in children with myopia.MethodsThe clinical data of 92 cases(176 eyes)of children with myopia treated in the First Affiliated Hospital of Zhengzhou University from Jun.2019 to Dec.2019 were collected.This study uses a prospective study.There were 50 male children(96 eyes)and 42 female children(80 eyes),aged 6 to 18 years.According to the eye conditions and personal wishes,they were divided into 2 groups:children in group A wore orthokeratology lenses,a total of 60 cases(114 eyes),the average age was(11.65±1.54)years old;children in group B wore single vision distance spectacles,a total of 32 cases(62 eyes),with an average age of(12.28± 1.73)years.Children in group A are required to wear lenses for no less than 8 hours each night.Children in group B are required to wear lenses all day.Follow-up is 6 months.Follow-up examinations are performed between 10:00 to 12:00 am.to limit various confounding factors.The inspection items include:visual acuity test(group A tests uncorrected visual acuity,group B tests corrected visual acuity),optometry refraction,slit lamp inspection of anterior segment and lens abrasion,corneal endothelial cytometer examination of corneal endothelial cell density and morphology,the IOL-Master checked the axial length,SS-OCTA checked the choroidal thickness and CVI.Results1.Comparing between the two groups,there was no significant difference in the density of corneal endothelial cells between the children before wearing lens and 6-month visit(before wearing lens t=-1.582,P=0.116;6-month visit t=1.618,P=0.108).There was no significant difference in the corneal endothelial cell density of the children in the two groups before wearing lens and 6-month visit.(Group A t=-0.183,P=0.855;Group B t=0.167,P=0.868).2.There was no significant difference in the axial length of the two groups before wearing lens(t=0.215,P=0.830).There was no significant difference in the axial length of the group A among before wearing lens,3-month visit and 6-months visit(F=1.521,P=0.220);There was a statistically significant difference in the axial length among before wearing lens,3-month visit and 6-month visit in group B(F=19.109,P<0.001);The comparison of the two groups within the group showed that the axial length was shorter in before wearing lens than in 3-month visit and 6-month visit,and 3-month visit is shorter than 6-month visit.The difference was statistically significant(P<0.05).The difference in axial length between the two groups in 3-month visit was statistically significant(t=-2.296,P=0.023),and the difference between the two groups in 6-month visit was statistically significant(t=-5.205,P<0.001).3.There was no significant difference in the thickness of each part of the choroid before wearing lens between the two groups(P>0.05),and the thickest part was temporal region(TI,TO)and the thinnest part was nasal region(NI,NO).The thickness of each part of the choroid in group A was significantly thicker during the follow-up period(P<0.05),while the thickness of each part of the choroid in group B did not change significantly(P>0.05).The difference of choroidal thickness between group A and group B was statistically significant(P<0.05),that is,the increase in 9 areas of choroid in group A was significantly greater than that in group B.Comparing the two groups separately,there was no significant difference of choroidal thickness in group B at different measurement time points(P>0.05);But there was significant difference of choroidal thickness in group A(P<0.05).And after pairwise comparison,it was concluded that T1 was greater than T2 and T3,T2 was greater than T3,that is,at the three measurement time points after Orthokeratology,the thickness of nine areas of choroid was significantly higher than before.4.There was no significant difference in CVI of each part of the choroid before wearing lens between the two groups(P>0.05),and the foveal area(F)was the largest,followed by the temporal area(TI3 TO)and the nasal area(NI,NO).The comparison of CVI difference in group B showed no statistical significance(P>0.05);the comparison of CVI difference in group A showed statistical significance(P<0.05).And after pairwise comparison,it is concluded that T1 is larger than T2 and T3,and there is no significant difference between T2 and T3.Compared between the two groups,there were significant differences in T1 and T2 in SI and NO regions(P<0.05),and no significant difference in T3(P>0.05);There were significant differences in T1 in NI,Ⅱ,TI,SO,IO,TO and F regions(P<0.05),and no significant difference in T2 and T3(P>0.05).Conclusion1.Orthokeratology has no significant effect on corneal endothelial cells,and it is safe to wear.2.Compared with single vision distance spectacles,Orthokeratology can significantly inhibit the growth of axial length.3.Compared with single vision distance spectacles,Orthokeratology can increase choroidal thickness and blood flow,and may have a certain effect on delaying the development of myopia. |
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