目的：评估在初治圆锥角膜患者中的角膜密度及其与前和后角膜仰角的相关性。

方法：使用Pentacam检测圆锥角膜。角膜密度测量是通过直径12 mm的区域测量， 分为环形同心区域和深度，测量更多的角膜前后仰角。根据地形圆锥角膜分类对圆锥角膜进行分类。

结果：研究包括152例患者\〖72例圆锥角膜患者(46例男性， 26例女性)和 80例健康对照受试者(50例男性， 30例女性)\〗。两组间角膜2 mm中心处和角膜环状2～6 mm直径处角膜密度测量值差异有统计学意义(K=16.40±2.18 GSU， N=15.31±1.25 GSU， P<0.0001)。当不同深度的密度测量值时，前部层呈现最高值，明显高于中央层和后层的值。当测量不同深度密度值时，前层呈现最高值(KC=23.69±3.71 GSU， N=20.91±2.52 GSU， P<0.0001)，显著高于中央层和后层值(KC=14.34±1.70 GSU， N=13.61±1.21 GSU， P=0.001； KC=11.40±1.23 GSU， N=12.35±0.88， P=0.002)。各层深度(前、中、后)角膜密度测量值与后角膜高度值的相关性分析显示两者显著相关(分别为r=0.293， r=0.278 和 r=0.294)。角膜光密度测定每层深度和角膜前角抬高之间没有发现类似的相关性(分别为r=-0.211， r=-0.101， r=0.99)。在对照组受试者中，未发现每层深度角膜前/后角膜高度和角膜后向散射的显著相关性。

结论：光密度图显示前圆锥角膜中央区域的光后向散射较高。圆锥角膜患者的角膜光密度值与角膜0～2、6～10、10～12 mm环状区域前、中、后各层角膜高度相关。

METHODS: Keratoconic corneas were examined using the Pentacam. Corneal densitometry was measured over a 12-mm diameter area, divided by annular concentric zones and depths, more over anterior and posterior corneal elevation was measured. Keratoconus was classified according to the topographic keratoconus classification.

RESULTS: A total of 152 subjects \〖72 patients with keratoconus(46 male, 26 female)and 80 healthy control subjects(50 male,30 female)\〗 were included in the study. There were significant differences in corneal densitometry values of the groups in central 2 mm keratoconus(KC)=19.62±4.17 gray scale unit(GSU), N=15.38±1.54 GSU(P<0.0001), and in annulus of 2 to 6 mm in diameter(K=16.40±2.18 GSU, N=15.31±1.25 GSU, P<0.0001). When densitometry values for different depths were examined, the anterior layer presented the highest value(KC=23.69±3.71 GSU, N=20.91±2.52 GSU, P<0.0001), which was significantly higher than the values obtained in the central and posterior layer(KC=14.34±1.70 GSU, N=13.61±1.21 GSU, P=0.001 and KC=11.40±1.23 GSU, N=12.35±0.88, P=0.002 respectively). Analysis of the correlation between corneal densitometry for each layer depth(anterior, central and posterior)with posterior corneal elevation values demonstrated significant association(r=0.293, r=0.278 and r=0.294 respectively). The similar correlation was not found between corneal densitometry for each layer depth and anterior corneal elevation(r=-0.211, r=-0.101, r=0.99 respectively). In the control patients such a significant correlation between posterior/anterior corneal elevation and corneal light backscatter for each layer depth was not found.

CONCLUSION: The densitometry map reveals that light backscatter was higher in the central portion of the anterior keratoconic cornea. Corneal densitometry values of keratoconus patients were correlated with posterior corneal elevation in 0-2, 6-10 and 10-12 annuli and in all anterior, central and posterior layers. The densitometry level was higher in more advanced stages.