圆锥角膜基底下神经与角膜形态的相关性研究

目的 研究圆锥角膜（KC）基底下神经与角膜形态的相关性。设计 前瞻性比较性病例系列。研究对象 2018年3月至2019年3月北京同仁医院KC患者（KC组）74例74眼，KC顿挫期组25例25眼，正常对照组24例24眼。方法 通过眼部检查及Pentacam眼前节分析仪诊断KC、KC顿挫期及正常角膜。角膜形态参数采用Pentacam的角膜最大曲率值（Kmax）和角膜最薄厚度值（Minpachy）。应用ACCmetrics软件计算由活体激光共聚焦显微镜（IVCM）获得的基底下神经图片上六种基底下神经参数：角膜神经纤维密度（CNFD）、角膜神经分支密度（CNBD）、角膜神经纤维长度（CNFL）、角膜总分支密度（CTBD）、角膜神经纤维面积（CNFA）、角膜神经纤维宽度（CNFW）。分析KC组角膜基底下神经与角膜形态的相关性，并比较各两组间角膜基底下神经参数的差异。主要指标 Kmax、Minpachy、CNFD、CNBD、CNFL、CTBD、CNFA、CNFW。结果 IVCM定性分析观察到KC组角膜基底下神经迂曲度增加、基底下神经纤维密度明显低，偶可见神经呈束状排列。KC组和正常对照组比较，CNFD、CNBD、CNFL和CNFW差异均有统计学意义（P均<0.05）。KC组和顿挫组比较，CNFL和CNFA差异均有统计学意义（P均<0.05）。顿挫组和正常对照组比较，CNFD和CNFL差异均有统计学意义（P均<0.05）。KC组CNFD、CNFL和CNFW分别与Kmax具有相关性（P=0.001、0.001和0.006）, KC组的CNFD、CNBD、CNFL和CNFW分别与Minpachy具有相关性（P=0.01、0.01、0.004和0.02）。结论 KC患者角膜基底下神经的改变可能早于角膜形态的改变，基底下神经随着疾病的进展而变化。CNFD和CNFL可能是诊断早期圆锥角膜的指标。（眼科， 2020, 29： 118-122）

The correlation study between keratoconus subbasal nerves and corneal morphology

Objective To study the correlation between corneal morphology and corneal subbasal nerves in patients with keratoconus(KC).Design Prospective comparative case series.Participants Seventy-four eyes of 74 patients with KC(25 of the other 74 eyes as frustrate keratoconus)and 24 eyes of 24 healthy patients were enrolled in this study from March 2018 to March 2019 in Beijing Tongren Hospital.Methods Patients were diagnosed and grouped as KC,frustrate KC or the normal by ophthalmic examination and Pentacam.Kmax(the maximum anterior corneal refractive power)and Minpachy(the minimum corneal thickness)of KC were applied as parameters of corneal shape.Images of subbasal nerves obtained with in vivo confocal microscopy(IVCM)were analyzed and calculated into 6 parameters by ACCmetrics software:corneal nerve fiber density(CNFD),corneal nerve branch density(CNBD),corneal nerve fiber length(CNFL),corneal total branch density(CTBD),corneal nerve fiber area(CNFA),and corneal nerve fiber width(CNFW).The correlation between subbasal nerves and corneal morphology in KC group was analyzed,and the differences of parameters between each group pair were compared.Main Outcome Measures Kmax,Minpachy,CNFD,CNBD,CNFL,CTBD,CNFA and CNFW.Results Qualitative analysis of IVCM showed that the subbasal nerves in KC showed a reduced density and increased tortuosity as compared to controls.The subbasal nerves in KC were arranged in bundles sometimes.Intergroup comparison showed statistically significant reduction in CNFD,CNBD,CNFL and CNFW in group KC as compared to group normal(all P<0.05).Intergroup comparison showed statistically significant reduction in CNFL and CNFA in keratoconus as compared to frustrate KC(both P<0.05).Intergroup comparison showed statistically significant reduction in CNFD and CNFL in the normal as compared to frustrate KC(both P<0.05).In correlation analysis,CNFD,CNFLand CNFW of KC patients were correlated with Kmax(P=0.001,0.001 and 0.006,respectively)and the CNFD,CNFL CNBD,and CNFW of KC patients were correlated with Minpachy(P=0.01,0.01,0.004,0.02).Conclusions In keratoconus,the changes in subbasal nerve may be earlier than the corneal shape.Subbasal nerve will change with the progress of keratoconus.Corneal nerve fiber density(CNFD)and corneal nerve fiber length(CNFL)might be applied as indicators for early diagnosis of keratoconus.