Tamaki Y, Araie M, Kawamoto E, Eguchi S, Fujii H
Eye Clinic, Tokyo Metropolitan Geriatric Hospital, Japan.
Exp Eye Res. 1995 Apr;60(4):373-83. doi: 10.1016/s0014-4835(05)80094-6.
A new apparatus has been developed using the laser speckle phenomenon for non-contact, two-dimensional analysis of tissue circulation in the choroid and optic nerve head (ONH). The fundus was illuminated by a diode laser spot and its image speckle was detected by an image sensor. The difference between the average of the speckle intensity (Imean) and the speckle intensity for successive scannings was calculated, and the ratio of Imean to this difference was defined as normalized blur (NB), which is a quantitative index of blood velocity. The results were displayed on color graphic monitors showing the two-dimensional variation of the NB level in the measurement field. In the rabbit, this apparatus was used to study the relationship between the results of NB measurement and the choroidal blood flow determined by the microsphere technique, the relationship between NB obtained from the ONH tissue free of visible surface vessels and the ocular perfusion pressure (OPP) after a lethal injection of pentobarital, and the effect of intraocular pressure (IOP) on the NB in the choroid or in the ONH. A stepwise reduction in the OPP was introduced by elevating the IOP manometrically. The relative decrease in the average NB over the field measured, NBav, in the choroid with the reduction in OPP showed a significant correlation with the relative change in the blood flow rate determined using the microsphere technique (r = 0.60, P < 0.001). NBav in the ONH had a good correlation with the OPP after a lethal injection of pentobarbital (r = 0.98, P < 0.001). NBav in the choroid decreased with reduction in the OPP. Although NBav in the ONH was little affected by OPP change when OPP was above 40 mmHg, at OPP levels below 40 mmHg, NBav in the ONH decreased along with a reduction in the OPP. These results suggest that by using the present apparatus, the blood velocity in the choroid or ONH under various conditions can be studied non-invasively in the living eye.
一种新装置已被开发出来，它利用激光散斑现象对脉络膜和视神经乳头（ONH）的组织循环进行非接触式二维分析。眼底由二极管激光光斑照明，其图像散斑由图像传感器检测。计算散斑强度平均值（Imean）与连续扫描的散斑强度之间的差异，并将Imean与该差异的比值定义为归一化模糊度（NB），它是血流速度的定量指标。结果显示在彩色图形监视器上，展示了测量区域内NB水平的二维变化。在兔子身上，该装置用于研究NB测量结果与通过微球技术测定的脉络膜血流之间的关系，从无可见表面血管的ONH组织获得的NB与戊巴比妥致死注射后的眼灌注压（OPP）之间的关系，以及眼内压（IOP）对脉络膜或ONH中NB的影响。通过手动升高IOP逐步降低OPP。随着OPP降低，脉络膜中测量区域的平均NB（NBav）相对下降与使用微球技术测定的血流速率相对变化显示出显著相关性（r = 0.60，P < 0.001）。戊巴比妥致死注射后，ONH中的NBav与OPP具有良好的相关性（r = 0.98，P < 0.001）。脉络膜中的NBav随着OPP降低而下降。虽然当OPP高于40 mmHg时，ONH中的NBav受OPP变化影响较小，但在OPP低于40 mmHg时，ONH中的NBav随着OPP降低而下降。这些结果表明，通过使用本装置，可以在活体眼中非侵入性地研究各种条件下脉络膜或ONH中的血流速度。
