方法：回顾性病例研究。收集2020-01/12在郑州市第二人民医院就诊的原发性圆锥角膜患者48例70眼，使用Pentacam眼前段分析系统测量角膜形态，包括角膜前表面中央扁平子午线曲率(K₁)、角膜前表面陡峭子午线曲率(K₂)、角膜前表面中央平均曲率(K_m)、角膜前表面最大曲率(K_max)、角膜前表面高度(ACE)、角膜后表面高度(PCE)、最薄点角膜厚度(TCT)，以及圆锥锥顶距角膜顶点的距离(DCA)。测量不同分区不同层次的角膜光密度。使用可视化角膜生物力学测量仪观察角膜形变过程并测量相关参数，包括第一次压平时间(AT₁)，第一次压平长度(AL₁)，第一次压平速度(V₁)，第二次压平时间(AT₂)，第二次压平长度(AL₂)，第二次压平速度(V₂)，最大压陷时间(HCT)，最大压陷形变幅度(HCDA)，最大压陷曲率半径(HCR)，最大压陷峰距(HCPD)，硬度参数(SPA1)，水平方向Ambrósio相关厚度(ARTh)。

结果：圆锥角膜患者距角膜顶点≤2mm前层光密度与K₁、K₂、K_m、K_max均呈正相关(r=0.291、0.315、0.315、0.387； P=0.015、0.008、0.008、0.001)。距角膜顶点≤2mm、>2mm且≤6mm前层及全层、>2mm且≤6mm后层光密度与ACE均呈正相关(r=0.465、0.302、0.317、0.291、0.335； P<0.01、P=0.011、0.008、0.014、0.005)； 上述各区域各层的光密度与PCE均呈正相关(r=0.565、0.369、0.348、0.306、0.284； P<0.01、P=0.002、0.003、0.010、0.017)。距角膜顶点≤2mm前、中、后及全层光密度，>2mm且≤6mm中、后及全层光密度均与AL₁均呈负相关(r=-0.284、-0.290、-0.245、-0.326、-0.282、-0.395、-0.310； P=0.017、0.015、0.041、0.006、0.018、0.001、0.009)。距角膜顶点≤2mm中层光密度、>2mm且≤6mm中、后层光密度与AL₂呈负相关(r=-0.246、-0.256、-0.256； P=0.041、0.032、0.032)。距角膜顶点≤2mm前层光密度与HCR呈负相关(r=-0.308，P=0.010)。距角膜顶点≤2mm中、后层光密度、>2mm且≤6mm中层光密度与HCT均呈负相关(r=-0.292、-0.340、-0.262； P=0.014、0.004、0.028)。距角膜顶点≤2mm前层及全层光密度、>2mm且≤6mm后层光密度与ARTh呈负相关(r=-0.430、-0.293、-0.319； P<0.01，P=0.014、0.007)。

结论：圆锥角膜患者角膜光密度测定值与角膜形态和生物力学特性相关，可能成为圆锥角膜的潜在诊断指标。

METHODS: Retrospective case study. A total of 70 eyes of 48 keratoconus patients were enrolled in this study. Corneal topography were measured using Pentacam, inclding the flat keratometry of anterior cornea(K₁), the steep keratometry of anterior cornea(K₂), the mean keratometry of anterior cornea(K_m), the maximum keratometry of anterior cornea(K_max), anterior corneal elevation(ACE), posterior corneal elevation(PCE), thinnest corneal thickness(TCT), and the distance from cone to apex(DCA). Corneal optical density of different corneal layers and zones were measured with the Scheimpflug-based Pentacam corneal densitometry module. Corneal biomechanical properties were measured using CorVis ST, inclding time of the first applanation(AT₁), length of the first applanation(AL₁), velocity of the first applanation(V₁), time of the second applanation(AT₂), length of the second applanation(AL₂), velocity of the second applanation(V₂), the highest concavity time(HCT), the highest concavity deformation amplitude(HCDA), the highest concavity radius(HCR), the highest concavity peak distance(HCPD), stiffness parameter applanation 1(SPA1), Ambrósio's relational thickness horizontal(ARTh).

RESULTS: Correlation between corneal densitometry and topographic parameters: The corneal densitometry values of the anterior ≤2mm layer correlated with the K₁, K₂, K_m and K_max values positively(r=0.291, 0.315, 0.315, 0.387; P=0.015, 0.008, 0.008, 0.001). The corneal densitometry values of the anterior ≤2mm, anterior >2 and ≤6mm, total ≤2mm, total >2 and ≤6mm, and posterior >2 and ≤6mm layers correlated with the anterior corneal elevation positively(r=0.465, 0.302, 0.317, 0.291, 0.335; P<0.01, P=0.011, 0.008, 0.014, 0.005), and also with the posterior corneal elevation(r=0.565, 0.369, 0.348, 0.306, 0.284; P<0.01, P=0.002, 0.003, 0.010, 0.017). Correlation between corneal densitometry and biomechanical properties: the corneal densitometry values of all ≤2mm, central >2 and≤6mm, posterior >2 and ≤6mm, and total >2 and ≤6mm layers all correlated with AL₁ negatively(r= -0.284, -0.290, -0.245, -0.326, -0.282, -0.395, -0.310; P=0.017, 0.015, 0.041, 0.006, 0.018, 0.001, 0.009). The corneal densitometry values of central ≤2mm, central >2 and ≤6mm, and posterior >2 and ≤6mm layers all correlated with AL₂ negatively(r= -0.246, -0.256, -0.256; P =0.041, 0.032, 0.032). The corneal densitometry values of anterior ≤2mm layer correlated with HCR negatively(r= -0.308, P=0.010). The corneal densitometry values of central ≤2mm, posterior ≤2mm, and certral >2 and ≤6mm layers all correlated with HCT negatively(r= -0.292, -0.340, -0.262; P=0.014, 0.004, 0.028). The corneal densitometry values of anterior ≤2mm, total ≤2mm, and posterior >2 and ≤6mm layers all correlated with ARTh negatively(r= -0.430, -0.293, -0.319; P<0.01, P = 0.014, 0.007).

CONCLUSION: The corneal densitometry values correlated with the severity of keratoconus and the biomechanical properties, and may became a potential diagnostic index of keratoconus.