Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland.
Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland.
Ophthalmology. 2020 Feb;127(2):167-176. doi: 10.1016/j.ophtha.2019.08.027. Epub 2019 Aug 29.
To assess the impact of OCT signal strength (SS) and artifact on retinal nerve fiber layer (RNFL) measurement reliability and to understand whether glaucoma severity modifies this relationship.
Retrospective, longitudinal cohort study.
Two thousand nine hundred ninety-two OCT scans from 474 eyes of 241 patients with glaucoma or glaucoma suspect status.
We extracted mean RNFL thickness and SS and manually graded scans for artifact. To analyze the effect of SS and artifact on OCT reliability, we (1) created a multilevel linear model using measured RNFL thickness values and demographic and clinical data to estimate the true (predicted) RNFL thickness, (2) calculated model residuals (ΔRNFL) as our reliability measure, and (3) created a second multilevel linear model with splines and interaction terms that modeled overall and quadrant specific reliability (ΔRNFL) as the outcome, using SS and artifact as predictors.
Impact of SS and artifact on ΔRNFL.
For SS between 10 and 3, the impact of decreases in SS on OCT reliability is modest (-0.67 to -1.25 ΔRNFL per 1-point decrease in SS; P < 0.05). But at less than 3, changes in SS have a large impact on reliability (-15.70 to -16.34 ΔRNFL per 1-point decrease in SS; P < 0.05). At SS between 10 and 3, decreases in SS tend to have a larger impact on reliability in eyes with severe glaucoma (-1.25 per 1-point decrease in SS; P < 0.05) compared with eyes with mild or moderate glaucoma (-0.67 to -0.75 per 1-point decrease in SS; P < 0.05). The presence of artifact has a significant impact on OCT reliability independent of the effects of SS (-4.76 ΔRNFL; P < 0.05). Artifact affects reliability solely in the quadrant in which it occurs, with artifact in one quadrant showing no impact on ΔRNFL in the opposite quadrant (P > 0.05).
Signal strength decreases down to 3 have relatively mild impacts on OCT reliability. At less than 3, the impact of further decreases in SS on reliability are substantial. The effect of SS on reliability is greater in severe glaucoma. Artifacts result in a decrease in reliability independent of the effect of SS. We propose evidence-based guidelines to guide physicians on whether to trust the results of an OCT scan.
评估 OCT 信号强度（SS）和伪影对视网膜神经纤维层（RNFL）测量可靠性的影响，并了解青光眼严重程度是否会改变这种关系。
回顾性、纵向队列研究。
来自 241 例青光眼或疑似青光眼患者的 474 只眼的 2992 次 OCT 扫描。
我们提取了平均 RNFL 厚度和 SS，并手动对扫描进行了伪影分级。为了分析 SS 和伪影对 OCT 可靠性的影响，我们 (1) 使用测量的 RNFL 厚度值和人口统计学及临床数据创建了一个多水平线性模型，以估计真实 (预测)RNFL 厚度，(2) 计算了模型残差 (ΔRNFL)，作为我们的可靠性测量，(3) 使用 SS 和伪影作为预测因子，创建了一个具有样条和交互项的第二个多水平线性模型，将整体和象限特异性可靠性 (ΔRNFL) 作为结果。
SS 和伪影对 ΔRNFL 的影响。
对于 SS 在 10 到 3 之间的情况，SS 降低对 OCT 可靠性的影响适度（SS 降低 1 点，ΔRNFL 降低 0.67 到 1.25；P < 0.05）。但是，在 SS 小于 3 时，SS 的变化对可靠性有很大影响（SS 降低 1 点，ΔRNFL 降低 15.70 到 16.34；P < 0.05）。在 SS 为 10 到 3 之间时，SS 降低对严重青光眼眼的可靠性影响较大（SS 降低 1 点，ΔRNFL 降低 1.25；P < 0.05），而对轻度或中度青光眼眼的影响较小（SS 降低 1 点，ΔRNFL 降低 0.67 到 0.75；P < 0.05）。伪影的存在对 OCT 可靠性有显著影响，独立于 SS 的影响（-4.76ΔRNFL；P < 0.05）。伪影仅对发生伪影的象限有影响，一个象限的伪影对其相对象限的 ΔRNFL 没有影响（P > 0.05）。
SS 降低至 3 对 OCT 可靠性的影响相对较小。在 SS 小于 3 时，SS 进一步降低对可靠性的影响较大。SS 对可靠性的影响在严重青光眼眼中更大。伪影的存在导致可靠性降低，而与 SS 的影响无关。我们提出了循证指南，以指导医生是否信任 OCT 扫描的结果。
