Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States.
Invest Ophthalmol Vis Sci. 2020 Nov 2;61(13):5. doi: 10.1167/iovs.61.13.5.
It is often suggested that structural change is detectable before functional change in glaucoma. However, this may be related to the lower variability and hence narrower normative limits of structural tests. In this study, we ask whether a time lag exists between the true rates of change in structure and function, regardless of clinical detectability of those changes.
Structural equation models were used to determine whether the rate of change in function (mean linearized total deviation, AveTDLin) or structure (retinal nerve fiber layer thickness [RNFLT]) was predicted by the concurrent or previous rate for the other modality, after adjusting for its own rate in the previous time interval. Rates were calculated over 1135 pairs of consecutive visits from 318 eyes of 164 participants in the Portland Progression Project, with mean 207 days between visits.
The rate of change of AveTDLin was predicted by its own rate in the previous time interval, but not by rates of RNFLT change in either the concurrent or previous time interval (both P > 0.05). Similarly, the rate of RNFLT change was not predicted by concurrent AveTDLin change after adjusting for its own previous rate. However, the rate of AveTDLin change in the previous time interval did significantly improve prediction of the current rate for RNFLT, with P = 0.005, suggesting a time lag of around six months between changes in AveTDLin and RNFLT.
Although RNFL thinning may be detectable sooner, true functional change appears to predict and precede thinning of the RNFL in glaucoma.
人们常说，在青光眼发生功能改变之前，结构就已经发生了改变。然而，这可能与结构测试的变异性较低，即标准范围较窄有关。在本研究中，我们想知道，无论结构和功能的变化是否具有临床可检测性，结构和功能的真实变化率之间是否存在时间滞后。
本研究使用结构方程模型来确定功能变化率（平均线性总偏差，AveTDLin）或结构变化率（视网膜神经纤维层厚度[RNFLT]）是否可以通过同一时间或前一时间间隔的另一模式的变化率来预测，同时调整了前一时间间隔内自身的变化率。该研究共纳入了来自波特兰进展项目的 318 只眼 164 名参与者的 1135 对连续就诊数据，平均随访间隔为 207 天。
AveTDLin 的变化率可以通过其前一时间间隔内的自身变化率来预测，但不能通过同一时间或前一时间间隔内的 RNFLT 变化率来预测（两者 P 值均>0.05）。同样，在调整自身前一时间间隔内的速率后，AveTDLin 的变化率也不能预测当前的 RNFLT 变化率。然而，前一时间间隔内的 AveTDLin 变化率确实显著改善了当前 RNFLT 速率的预测，P 值为 0.005，提示 AveTDLin 和 RNFLT 之间的变化存在约 6 个月的时间滞后。
尽管 RNFL 变薄可能更早被检测到，但在青光眼患者中，真正的功能改变似乎先于 RNFL 变薄。
