Barry J C, Effert R, Kaupp A, Kleine M, Reim M
Augenklinik, Medizinische Einrichtungen, RWTH Aachen.
Ophthalmologe. 1994 Feb;91(1):51-61.
A digital image recording and processing system is presented that allows a quick diagnosis of microstrabismus in non-cooperative children. It is thus particularly suited for screening purposes.
The Purkinje Reflection Pattern Evaluation (RPE) method is used: three small flashes are used to produce the desired Purkinje images. Two horizontal rows of the three 1st Purkinje images (anterior corneal reflections) and of the three 4th Purkinje images (posterior crystalline lens reflections) stemming from the three light sources form the characteristic Purkinje image reflection pattern. Each eye's position is calculated from the shift between the upper and lower rows of reflections by means of two simple formulae. From the angles obtained in binocular fixation and monocular fixation the manifest angle of strabismus corresponding to the angle measured in the simultaneous prism-and-cover test is computed. The measurement is performed at a fixation distance of 50 cm under natural viewing conditions. To obtain a picture one only has to get the child's attention for a short moment. The primary position is triggered with the fixation light, which is operated by a switch.
The digital image recording is done with a hand-held device comprising two miniaturized video cameras, three photo flashes and a fixation light that is operated manually. An IBM-compatible PC equipped with a hard disk and two frame grabbers was adapted for the storage and processing of the pictures. The pictures are evaluated interactively in a few minutes on the workstation's monitor immediately after the measurement. To this end specially designed menu-driven software was implemented.
Examples of the measuring procedure and clinical results in infants with microtropic highlight the potential of the system as a screening apparatus and for the exact measurement of small and large squint angles. Usually even 1-year-old children can cooperate well enough to get good-quality pictures in binocular fixation. The new digital system allows easy and rapid application of the Purkinje Reflection Pattern Evaluation method since the time-consuming photographic film processing and evaluation are no longer necessary. For the first time small angles of strabismus under 5 degrees (10 PD) can be measured with a precision of less than 1 degree (2 PD) under clinical conditions in non-cooperative children.
本文介绍了一种数字图像记录与处理系统，该系统能够快速诊断不配合的儿童的微小斜视。因此，它特别适用于筛查目的。
采用浦肯野反射模式评估（RPE）方法：使用三个小闪光来产生所需的浦肯野图像。来自三个光源的三个第一浦肯野图像（角膜前反射）和三个第四浦肯野图像（晶状体后反射）的两排水平图像形成了特征性的浦肯野图像反射模式。通过两个简单公式，根据上下排反射之间的偏移计算每只眼睛的位置。从双眼注视和单眼注视获得的角度计算出与同时棱镜遮盖试验中测量的角度相对应的显性斜视角度。测量在自然观察条件下50厘米的注视距离处进行。为了获得图像，只需让孩子短时间注意即可。通过由开关操作的注视光触发初始位置。
数字图像记录通过一个手持设备完成，该设备包括两个小型化摄像机、三个闪光灯和一个手动操作的注视光。一台配备硬盘和两个图像采集卡的IBM兼容个人计算机用于图像的存储和处理。测量后，在工作站的监视器上几分钟内即可交互式地评估图像。为此，实施了专门设计的菜单驱动软件。
微小斜视婴儿的测量过程和临床结果示例突出了该系统作为筛查设备以及精确测量小斜视角度和大斜视角度的潜力。通常，即使是1岁的儿童也能很好地配合，以获得双眼注视时的高质量图像。新的数字系统使得浦肯野反射模式评估方法的应用变得简单快捷，因为不再需要耗时的胶卷冲洗和评估。首次在临床条件下，能够在不配合的儿童中以小于1度（2棱镜度）的精度测量5度（10棱镜度）以下的小斜视角度。
