Bascom Palmer Eye Institute, Miller School of Medicine University of Miami, Miami, FL, USA.
Bascom Palmer Eye Institute, Miller School of Medicine University of Miami, Miami, FL, USA.
Exp Eye Res. 2019 Sep;186:107738. doi: 10.1016/j.exer.2019.107738. Epub 2019 Jul 17.
This study investigated temporal change of retinal nerve fiber layer (RNFL) reflectance speckle in retinas with ocular hypertensive (OHT) damage and in control retinas from untreated eyes. Experimental OHT damage to rat retinas was induced by laser photocoagulation of the trabecular meshwork. A series of 660 nm reflectance images was collected from isolated retinas at 10-sec intervals. Areas containing speckled texture were selected on nerve fiber bundles. Correlation coefficients between images with different imaging delays were calculated and plotted as a function of delay. To evaluate the temporal change of speckles, decay of correlation coefficients with time was fitted with an exponential function characterized by a time constant τ. Reflectance per unit thickness (σ) of the areas was also measured and low σ was used as a surrogate of OHT damage. Speckle phenomena occurred in the control RNFL and the RNFL with reduced σ. In the control retinas, τ and σ were nearly constant along bundles but differed significantly among bundles in the same retinas. Among the control retinas, σ was similar, whereas τ varied significantly. In the retinas with OHT damage (low σ) τ could be within, greater or lower than the range in controls. The parameters τ and σ provide independent assessment of the RNFL with OHT damage. Measurements of temporal change of RNFL reflectance speckle may offer a method for detecting functional abnormality of the RNFL.
本研究旨在探讨伴有眼高压（OHT）损伤的视网膜神经纤维层（RNFL）反射斑点的时间变化，以及未经治疗的对照眼视网膜的变化。通过激光光凝小梁网，对大鼠视网膜造成实验性 OHT 损伤。从分离的视网膜每隔 10 秒采集一系列 660nm 反射图像。在神经纤维束上选择含有斑点纹理的区域。计算不同成像延迟的图像之间的相关系数，并作为延迟的函数绘制。为了评估斑点的时间变化，用具有时间常数 τ 的指数函数拟合相关系数随时间的衰减。还测量了区域的单位厚度反射率（σ），低 σ 被用作 OHT 损伤的替代物。在对照 RNFL 和反射率降低的 RNFL 中都出现了斑点现象。在对照视网膜中，τ 和 σ 在束内几乎保持不变，但在同一视网膜中的束之间差异显著。在对照视网膜中，σ 相似，但 τ 差异显著。在伴有 OHT 损伤（低 σ）的视网膜中，τ 可以在对照组的范围内，也可以大于或小于对照组的范围。参数 τ 和 σ 可独立评估伴有 OHT 损伤的 RNFL。RNFL 反射斑点时间变化的测量可能提供一种检测 RNFL 功能异常的方法。
