中国近视人群双眼角膜最薄点厚度和位置分析

摘要

背景 中央角膜厚度(CCT)是评估角膜健康状况、指导疾病诊治、设计角膜屈光手术方案的重要参数,但近来的研究表明角膜顶点并不是角膜最薄点,因此有必要对角膜最薄点的厚度和位置进行深入探讨.目的 研究中国近视人群角膜最薄点与CCT的差值和距离以及双眼角膜最薄点的对称关系,探讨其规律及临床意义. 方法 采用Pentacam HR眼前节成像系统对282例564眼中国近视患者的角膜进行三维重建,以角膜顶点为中心,确定角膜最薄点的位置,分析左右眼间不同部位角膜厚度的差异、角膜顶点CCT与角膜最薄点的差异和距离以及双眼角膜最薄点之间的结构对称性.结果 右眼平均CCT为(540.07±31.78) μm,左眼为(539.24±31.06) μm;右眼瞳孔中央角膜厚度(PCT)平均为(540.25±30.75) μm,左眼为(539.48±31.00)μm;右眼最小角膜厚度(MCT)平均值为(537.87±30.91) μm,左眼为(536.35±31.24)μm,除PCT外,双眼间CCT、MCT的差异均有统计学意义(CCT:P=0.046;PCT:P=0.065;MCT:P=0.000).双眼间CCT、PCT、MCT值均呈线性正相关(r=0.97、0.97、0.98,P＜0.01).Bland-Altman图分析显示,双眼的角膜厚度具有良好的一致性.角膜最薄点距离角膜顶点的距离右眼为(0.50±0.21)mm,左眼为(0.56±0.22) mm,双眼角膜最薄点的位置差异有统计学意义(P=0.000);右眼CCT与MCT间的差值为(2.20±1.74) μm,左眼为(2.88±1.75) μm,左右眼间比较差异有统计学意义(P=0.000).双眼角膜最薄点的位置趋向于垂直轴对称.右眼角膜最薄点位置与按垂直轴对称转化后的左眼角膜最薄点位置平均距离为(0.29±0.17)mm,角度为(28.28±28.21)°.结论 本研究为中国近视人群角膜最薄点的厚度和位置提供了参考数据.双眼的CCT和MCT具有差异性,角膜最薄点的位置具有结构对称性.这些参数的改变可能为发现某些疾病提供线索.%Background Central corneal thickness (CCT)is an important parameter to evaluate corneal healthy status and is crucial for surgical planning.However,clinical study found that the center of cornea does not correspond to the thinnest point of cornea.Thus,it is essential to characterize the minimum corneal thickness(MCT) and its location.Objective Present study was to determine the thickness and location of MCT and its relationship to the fellow eye using Pentacam High Resolution technique.Methods The 564 eyes from 282 Chinese myopic patients were reviewed in this study.The CCT,MCT,pupillary central corneal thickness(PCT) and x-y coordinate of thinnest point were bilaterally measured.Written informed consent was obtained prior to the ocular biomedical measurement.Results CCT was (540.07±31.78) μm in the right eyes and (539.24±31.06) μm in the lefi eyes; PCT was (540.25±30.75)μm in the right eyes and (539.48±31.00)μm in the left eyes.MCT was (537.87± 31.91)μm in the right eyes and (536.35±31.24)μm in the left eyes,showing significant differences in all the parameters between the right eyes and left eyes expect for PCT(CCT:P=0.046;PCT:P=0.065 ;MCT:P=0.000).The C CT,PCT and M CT were significantly correlated between the right eyes and left eyes (r =0.97,0.97,0.98,P＜ 0.01).Bland-Altman plot showed a good consistence between the both eyes.The mean distance from the center was (0.50±0.21) mm in the right eyes and (0.56±0.22)mm in the left eyes,showing a significant difference (P =0.000).The difference between CCT and MCT was approximately (2.20±1.74)μm in the right eyes and (2.88±1.75) μm in the left eyes.The location of MCT in both the right eyes and left eyes tended to symmetry along the vertical midline.The distance between the R (x,y) to transformed L (x,y) was (0.29 ± 0.17)mm and the angular distance was (28.28±28.21)degree.Conclusions This study offers a range of MCT and its location in Chinese myopic patients.The difference exists between the CCT and MCT in bilateral eyes.The location of the thinnest point tends to be symmetrical along the vertical midline between the both eyes.The changes of these parameters may be helpful for the diagnosis of some corneal diseases.