Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.
Cornea. 2020 Jun;39(6):761-768. doi: 10.1097/ICO.0000000000002307.
To investigate the changes in corneal backward scattering using Scheimpflug tomography (densitometry) 6 months after intrastromal corneal ring segments (Keraring) implant for keratoconus and to correlate with clinical results.
Along with standard ophthalmic examination, Scheimpflug tomography using Pentacam HR was performed to document corneal densitometry and corneal shape. A densitometry map was displayed using grayscale units (GSUs) ranging from 0 to 100 (minimum to maximum light scattering) in 4 concentric annuluses: central 2-, 2- to 6-, 6- to 10-, 10- to 12-, and total 12-mm corneal diameter and at 3 different depths: anterior 120 μm, posterior 60 μm, middle (varying accordingly to the total thickness), and total thickness.
The changes in mean corneal densitometry values for anterior, central, and posterior layers were 3.82 ± 3.13, 2.70 ± 1.78, and 1.68 ± 1.52 GSU, respectively, and for annuluses of 0 to 2, 2 to 6, 6 to 10, and 10 to 12 mm were 2.96 ± 2.60, 4.53 ± 2.28, 2.09 ± 1.74, and 0.45 ± 3.93 GSU, respectively. The mean values increased for all corneal layers (P < 0.05), except in the peripheral 10- to 12-mm annulus (P> 0.05). The highest increase was in the annulus 2 to 6 mm of the anterior layer (5.72 ± 3.70 GSU). Changes in the mean densitometry showed a significant correlation with the mean of average keratometry changes only for the front corneal surface and changes in the Q-values for both corneal surfaces in the 2- to 6-mm annulus for all layers.
Significant increase in the corneal densitometry mainly in the anterior 2- to 6-mm annulus of the cornea is associated with the position of the ring segment implant. More studies are needed to elucidate the relevance of such findings.
研究基质内角膜环段（角膜环）植入治疗圆锥角膜 6 个月后角膜后向散射的变化，并与临床结果相关联。
除了标准的眼科检查外，还使用 Pentacam HR 进行 Scheimpflug 体层摄影术以记录角膜密度和角膜形状。使用灰度单位（GSUs）显示密度图，范围从 0 到 100（最小到最大光散射），分为 4 个同心环：中央 2-、2-6-、6-10-和 10-12-，以及总 12mm 角膜直径和 3 个不同深度：前 120μm、后 60μm、中间（根据总厚度而变化）和总厚度。
前、中央和后层的平均角膜密度值变化分别为 3.82±3.13、2.70±1.78 和 1.68±1.52GSU，0-2、2-6、6-10 和 10-12mm 环的变化分别为 2.96±2.60、4.53±2.28、2.09±1.74 和 0.45±3.93GSU。所有角膜层的平均密度值均增加（P<0.05），除了周边 10-12mm 环（P>0.05）外。前层 2-6mm 环的增加最高（5.72±3.70GSU）。平均密度变化与前角膜表面平均角膜曲率变化的平均值和角膜表面 Q 值变化呈显著相关性，所有层的 2-6mm 环的变化均在前角膜表面和角膜表面 Q 值。
角膜密度的显著增加主要在前部 2-6mm 角膜环段与环段植入位置有关。需要进一步研究阐明这些发现的相关性。
