Department of Ophthalmology, Antwerp University Hospital (UZA), Edegem, Belgium.
Department of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium ; and.
Cornea. 2021 Feb 1;40(2):194-202. doi: 10.1097/ICO.0000000000002458.
To report an observation made while performing Scheimpflug densitometry analysis on the corneal region affected in keratoconus (KC) that seems to delineate the base of the cone.
Scheimpflug densitometries of 20 healthy subjects and 90 patients with KC were examined. Corneal densitometry was analyzed using both "1-layer" and "2-layer" approaches. The first considers the corneal transparency layer by layer at different depths, whereas the second averages densitometry between 2 corneal layers selected by the examiner. Fixed layers, 120 μm depth, and endothelium were selected. Repeated same-day scans and longitudinal series of scans were also evaluated to see whether the findings evolved over time.
Eighty-eight of 90 KC cases displayed a bright area on the densitometry map that corresponded to the cone location. The area's characteristics, such as its brightness, contrast, and the presence of a delimiting arc correlated with KC severity and was more noticeable in advanced cases. No similar marks were found in any of the normal subjects. The shape, location, and extent of the mark were consistent over consecutive measures taken on the same day. Changes over time were also seen in eyes with known clinical progression but was also seen in eyes considered clinically stable.
The densitometry mark seems to correspond with the zone most affected by KC and could be a supplementary tool for documenting KC stage, alongside conventional parameters. Further studies are required to ascertain whether it could prove useful in KC detection, to determine progression, and to relate it to corneal biomechanical behavior.
报告在进行圆锥角膜（KC）角膜区域的 Scheimpflug 密度分析时观察到的现象，该现象似乎描绘了圆锥的底部。
检查了 20 名健康受试者和 90 名 KC 患者的 Scheimpflug 密度计。使用“1 层”和“2 层”方法分析角膜密度。第一种方法逐层分析角膜在不同深度的透明度，而第二种方法则通过检查者选择的 2 个角膜层之间的平均密度。选择固定层、120μm 深度和内皮细胞。还评估了相同日期的重复扫描和纵向系列扫描，以观察结果是否随时间演变。
90 例 KC 病例中有 88 例在密度图上显示出一个明亮区域，该区域对应于圆锥的位置。该区域的特征，如亮度、对比度和存在限定弧，与 KC 的严重程度相关，在晚期病例中更为明显。在任何正常受试者中均未发现类似的标记。标记的形状、位置和范围在同一天进行的连续测量中是一致的。在已知临床进展的眼中也观察到了随时间的变化，但在被认为临床稳定的眼中也观察到了这种变化。
密度计标记似乎与受 KC 影响最严重的区域相对应，除了常规参数外，它可能成为记录 KC 阶段的辅助工具。需要进一步的研究来确定它是否在 KC 检测、确定进展以及将其与角膜生物力学行为相关方面有用。
