Corneal Elevation Topography In Chronic Primary Angleclosure Glaucoma

ObjectiveTo compare the differences in corneal topography between primary chronic angle-closure glaucoma(CPACG)and healthy volunteers,and to explore the characteristics of corneal topography of CPACG.MethodsCross-sectional study.Collect relevant data of CPACG patients and healthy volunteers(normal control group)who visited the ophthalmology department of our hospital from January 2019 to December 2019.All subjects were examined by Pentacam three-dimensional corneal topography,Humphrey standard automatic perimeter,and retinal optical correlation tomography(OCT).Statistical analysis of14 cornea topographic map indexes of Pentacam HD scan: horizontal central curvature(K1),vertical central curvature(K2),maximum K value,corneal thinnest point thickness,anterior surface deviation index Df,posterior surface height deviation Index Db,corneal thickness variation deviation index Dp,thinnest point thickness difference value Dt,relative thickness difference Da,overall deviation index D,the apex of the corneal front and back surface based on the standard best fit spherical(BFS)height map,the cornea center 3mm,5mm,7mm maximum height on the ring.The independent sample t test was used to compare the mean difference between the normal control group and the CPACG group.Spearman correlation coefficient was used to analyze the correlation between the corneal height value on each ring and IOP,MD,RNFL thickness around the optic disc,and vertical C / D.Receiver operating characteristic(ROC)curve and Logistic regression model were used to calculate the optimal cut-off value and diagnostic efficiency of variables.Results52 cases(52 eyes)were included in the CPACG group and 52 cases(52 eyes)were included in the normal control group.There was no statistically significant difference in the age,prevalence of diabetes,prevalence of hypertension,sex ratio,central corneal thickness,and thinnest cornea of the two groups,point thickness,K1,K2,corneal maximum curvature K,Dt,Da.The values of Df,Db,Dp,the apex of the cornea front and back surface,and the maximum height of the 3mm ring in the CPACG group were larger than those in the normal control group(P <0.05).The height of the corneal surface in the CPACG group was positively correlated with IOP,positively correlated with vertical C / D,and positively correlated with the degree of visual field defect.Both the anterior and posterior corneal surfaces were convex forward.This change was more pronounced on the posterior corneal surface than the corneal anterior surface.Especially at 3mm from the center of the cornea.The corneal anterior surface apex,anterior surface center 3mm ring,posterior surface apex,and posterior surface 3mm ring ROC area(AUC)> 0.6,combined with corneal anterior and posterior surface apex,maximum value on3 mm ring,the highest diagnostic efficiency,AUC = 0.855,Youden index = 0.6154,sensitivity = 65.38%,specificity = 96.15%.ConclusionsCompared with healthy people,the anterior and posterior corneal projections of CPACG patients are more pronounced,and this degree of corneal projection has a certain diagnostic effect on CPACG.Under the control of CCT,every 1mm Hg increase in intraocular pressure The rear surface apex protrudes 0.226 um forward.The pathological increase of intraocular pressure in glaucoma not only causes damage to the visual field and optic nerve,but also has a certain impact on the corneal structure and changes in corneal morphology.It can be used as an observation index in the diagnosis and follow-up of CPACG.