Kanellopoulos Anastasios John, Aslanides Ioannis M, Asimellis George
Laservision Eye Institute, Athens.
Clin Ophthalmol. 2012;6:789-800. doi: 10.2147/OPTH.S31524. Epub 2012 May 23.
To determine and correlate epithelial corneal thickness (pachymetric) measurements taken with a digital arc scanning very high frequency ultrasound biomicroscopy (HF UBM) imaging system (Artemis-II), and compare mean and central epithelial thickness among normal eyes, untreated keratoconic eyes, and keratoconic eyes previously treated with collagen crosslinking (CXL).
Epithelial pachymetry measurements (topographic mapping) were conducted on 100 subjects via HF UBM. Three groups of patients were included: patients with normal eyes (controls), patients with untreated keratoconic eyes, and patients with keratoconic eyes treated with CXL. Central, mean, and peripheral corneal epithelial thickness was examined for each group, and a statistical study was conducted.
Mean, central, and peripheral corneal epithelial thickness was compared between the three groups of patients. Epithelium thickness varied substantially in the keratoconic group, and in some cases there was a difference of up to 20 μm between various points of the same eye, and often a thinner epithelium coincided with a thinner cornea. However, on average, data from the keratoconic group suggested an overall thickening of the epithelium, particularly over the pupil center of the order of +3 μm, while the mean epithelium thickness was on average +1.1 μm, compared to the control population (P = 0.005). This overall thickening was more pronounced in younger patients in the keratoconic group. Keratoconic eyes previously treated with CXL showed, on average, virtually the same average epithelium thickness (mean -0.7 μm, -0.2 μm over the pupil center, -0.9 μm over the peripheral zone) as the control group. This finding further reinforces our novel theory of the "reactive" component of epithelial thickening in corneas that are biomechanically unstable, becoming stable when biomechanical rigidity is accomplished despite persistence of cornea topographic irregularity.
A highly irregular epithelium may be suggestive of an ectatic cornea. Our results indicate that the epithelium is thinner over the keratoconic protrusion, but to a much lesser extent than anticipated, and on average epithelium is thicker in this group of patients. This difference appears to be clinically significant and may become a screening tool for eyes suspected for ectasia.
使用数字弧形扫描超高频超声生物显微镜（HF UBM）成像系统（Artemis-II）测定角膜上皮厚度（测厚）并进行相关性分析，比较正常眼、未经治疗的圆锥角膜眼以及先前接受过胶原交联（CXL）治疗的圆锥角膜眼的平均上皮厚度和中央上皮厚度。
通过HF UBM对100名受试者进行上皮测厚测量（地形图绘制）。纳入三组患者：正常眼患者（对照组）、未经治疗的圆锥角膜眼患者以及接受过CXL治疗的圆锥角膜眼患者。对每组的中央、平均和周边角膜上皮厚度进行检查，并进行统计学研究。
比较了三组患者的平均、中央和周边角膜上皮厚度。圆锥角膜组的上皮厚度差异很大，在某些情况下，同一只眼的不同点之间相差可达20μm，而且上皮变薄往往与角膜变薄同时出现。然而，平均而言，圆锥角膜组的数据表明上皮总体增厚，尤其是在瞳孔中心上方约+3μm，而平均上皮厚度平均为+1.1μm，与对照组相比（P = 0.005）。这种总体增厚在圆锥角膜组的年轻患者中更为明显。先前接受过CXL治疗的圆锥角膜眼平均显示出与对照组几乎相同的平均上皮厚度（平均-0.7μm，瞳孔中心上方-0.2μm，周边区域-0.9μm）。这一发现进一步强化了我们关于生物力学不稳定角膜上皮增厚的“反应性”成分的新理论，即尽管角膜地形图不规则持续存在，但当生物力学刚度实现时，角膜上皮会变得稳定。
高度不规则的上皮可能提示角膜扩张。我们的结果表明，在圆锥角膜突出部位上皮较薄，但程度远低于预期，并且该组患者的上皮平均更厚。这种差异似乎具有临床意义，可能成为疑似扩张眼的筛查工具。
