Jonas J B, Montgomery D M
Department of Ophthalmology, University Eye Hospital, Erlangen, Germany.
Graefes Arch Clin Exp Ophthalmol. 1995 Nov;233(11):690-3. doi: 10.1007/BF00164670.
This study evaluated whether the neuroretinal rim area can be calculated on the basis of the horizontal and vertical diameters of the optic disc and cup applying the formula of an ellipse.
Color stereo optic disc photographs of 587 normal subjects and 1193 patients with glaucoma were morphometrically examined. In a first method, the areas of the optic disc and cup were planimetrically measured and the area of the neuroretinal rim was determined as optic disc area minus cup area. In a second method, the optic disc and cup were assumed to have an elliptical shape. Their areas were calculated by applying the formula of an ellipse, taking into account their horizontal and vertical diameters. As in the first method, the rim area was then determined as disc area minus cup area.
The values of the neuroretinal rim area as measured using the first method differed by 0.05 +/- 0.05 mm2 from the values as calculated by the second method. The average error was 2.8 +/- 2.9% for the normal group and 8.2 +/- 20.8% for the glaucoma patients. It increased with decreasing neuroretinal rim area and increasing mean visual field defect.
For clinical purposes, the neuroretinal rim area can be determined on the basis of the horizontal and vertical diameters of the optic disc and cup. The horizontal and vertical disc and cup diameters being determinable upon ophthalmoscopy, this finding is important for the direct measurement of optic disc morphology during any ophthalmoscopic examination.
本研究评估了是否可以根据视盘和视杯的水平及垂直直径，运用椭圆公式来计算神经视网膜边缘区域。
对587名正常受试者和1193名青光眼患者的彩色立体视盘照片进行形态测量检查。第一种方法是，采用平面测量法测量视盘和视杯的面积，神经视网膜边缘区域的面积通过视盘面积减去视杯面积来确定。第二种方法是，假设视盘和视杯为椭圆形。考虑到它们的水平和垂直直径，运用椭圆公式计算其面积。与第一种方法一样，边缘区域面积随后通过视盘面积减去视杯面积来确定。
第一种方法测量的神经视网膜边缘区域面积值与第二种方法计算的值相差0.05±0.05平方毫米。正常组的平均误差为2.8±2.9%，青光眼患者为8.2±20.8%。误差随着神经视网膜边缘区域面积减小和平均视野缺损增加而增大。
出于临床目的，可以根据视盘和视杯的水平及垂直直径来确定神经视网膜边缘区域面积。由于在检眼镜检查时可确定视盘和视杯的水平及垂直直径，这一发现对于在任何检眼镜检查期间直接测量视盘形态具有重要意义。
