Department of Ophthamology, University Medical Center of Saarland UKS, Homburg/Saar, Germany.
Acta Ophthalmol. 2013 Feb;91(1):e29-34. doi: 10.1111/j.1755-3768.2012.02519.x. Epub 2012 Aug 31.
The aim of our study was to investigate the biomechanical properties of the cornea in primary congenital glaucoma (PCG) and to identify the potential ocular determinants, which affect the corneal biomechanical metrics.
Corneal hysteresis (CH), corneal resistance factor (CRF) and central corneal thickness (CCT) were measured in 26 patients with PCG (40 eyes) with the aid of ocular response analyser. In vivo laser-scanning confocal microscopy was used for the estimation of stromal keratocyte density (KD) and the evaluation of corneal endothelium. Twenty normal subjects (40 eyes) served as controls. Student's t-test and Pearson's correlation coefficients were used for statistical analysis. p Values <0.05 were considered statistically significant.
Corneal hysteresis, CRF and CCT were significantly reduced in patients with PCG (all p < 0.05). Corneal hysteresis and CRF negatively correlated with the corneal diameter in both groups (r(1) = -0.53, r(2) = -0.66, p < 0.001 for CH and r(1) = -0.61, r(2) = -0.69, p < 0.001 for CRF). Moreover, we identified a significant correlation between CH and CRF with CCT in both groups (r(1) = 0.51, r(2) = 0.48, p < 0.001 for CH and r(1) = 0.45, r(2) = 0.44, p < 0.001 for CRF). Mean KD was significantly reduced both in the anterior and posterior corneal stroma in patients with PCG (764 ± 162 and 362 ± 112 cells/mm(2) , respectively) compared with controls (979 ± 208 and 581 ± 131 cells/mm(2) , respectively) (p < 0.001). There was no significant correlation between the keratocyte density in anterior and/or posterior stroma and CH or CRF in any group (r(1) = 0.29, r(2) = 0.31, p < 0.06). Mean endothelial cell density was also significantly reduced in PCG group (2920 ± 443 cells/mm(2) ) compared with control group (3421 ± 360 cells/mm(2) ) (p < 0.001). Pleomorphism and polymegalism were significantly increased in corneal endothelium of patients with PCG.
Our results showed a significant reduction in CH and CRF in PCG. Both CH and CRF were negatively correlated with corneal diameter. A significant correlation of CH and CRF with CCT was identified in both groups. Keratocyte density was decreased in PCG, but did not have a significant impact on CH and CRF. Mean endothelial density was also decreased in PCG. Our results suggest that reduced CCT and increased corneal diameter are major ocular determinants for the modified corneal biomechanical profile in PCG, while cellular alterations in corneal stroma and endothelium have no significant biomechanical impact.
本研究旨在探讨原发性先天性青光眼（PCG）患者角膜的生物力学特性，并确定潜在的眼内决定因素，这些因素可能影响角膜生物力学参数。
使用眼反应分析仪（ORA）测量 26 例 PCG 患者（40 只眼）的角膜滞后（CH）、角膜阻力因子（CRF）和中央角膜厚度（CCT）。利用共聚焦激光扫描显微镜对基质成纤维细胞密度（KD）进行评估，并对角膜内皮细胞进行评价。20 名正常受试者（40 只眼）作为对照组。采用学生 t 检验和 Pearson 相关系数进行统计学分析。p 值<0.05 被认为具有统计学意义。
PCG 患者的角膜滞后、CRF 和 CCT 均显著降低（均 p<0.05）。在两组中，角膜滞后和 CRF 均与角膜直径呈负相关（r(1)=-0.53，r(2)=-0.66，p<0.001 用于 CH 和 r(1)=-0.61，r(2)=-0.69，p<0.001 用于 CRF）。此外，我们还发现两组中 CH 和 CRF 与 CCT 之间存在显著相关性（r(1)=0.51，r(2)=0.48，p<0.001 用于 CH 和 r(1)=0.45，r(2)=0.44，p<0.001 用于 CRF）。与对照组相比，PCG 患者的角膜前部和后部基质中的平均 KD 均显著降低（分别为 764±162 和 362±112 个细胞/mm²，p<0.001）。与对照组相比，PCG 患者的角膜前部和后部基质中的平均 KD 均显著降低（分别为 764±162 和 362±112 个细胞/mm²，p<0.001）。与对照组相比，PCG 患者的角膜前部和后部基质中的平均 KD 均显著降低（分别为 764±162 和 362±112 个细胞/mm²，p<0.001）。在任何一组中，角膜成纤维细胞密度与 CH 或 CRF 之间均无显著相关性（r(1)=0.29，r(2)=0.31，p<0.06）。PCG 组的平均内皮细胞密度（2920±443 个细胞/mm²）也显著低于对照组（3421±360 个细胞/mm²）（p<0.001）。PCG 患者的角膜内皮细胞出现明显的多形性和多核性改变。
我们的研究结果显示，PCG 患者的 CH 和 CRF 显著降低。CH 和 CRF 均与角膜直径呈负相关。在两组中，CH 和 CRF 与 CCT 之间存在显著相关性。PCG 患者的角膜基质成纤维细胞密度降低，但对 CH 和 CRF 无显著影响。平均内皮细胞密度也在 PCG 中降低。我们的研究结果表明，降低的 CCT 和增加的角膜直径是 PCG 角膜生物力学特征改变的主要眼内决定因素，而角膜基质和内皮细胞的改变对角膜生物力学特征没有显著影响。
