The present invention relates to a method for analyzing a stereoscopic image of a fundus to detect and analyze the optic disk on the basis of the stereoscopic image of the fundus, and an apparatus for executing that method.
Glaucoma is known as a disease of the visual function. In the examination of glaucoma, it is said that the observation of patient's optic disk on the basis of an image of the fundus is important. In recent years, it has become possible to quantitatively measure the optic disk due to progress in the technology of image analysis. As the results of analysis, the following parameters are computed: the C/D ratio (a distance ratio between a rim of an optic disk cupping (the optic disk cupping being referred to as a cup) and a rim of the optic disk (the optic disk being referred to as a disk)), the area of the plane within the cup rim, the depth of the cup, the volume of the cup, and the like.
The rim of the cup which serves as a basis for the computation of these parameters is conventionally detected such that, by using the disk as a reference, positions which are lowered by an arbitrary depth (e.g., 150 .mu.m) from the disk are estimated to plot the rim of the cup.
However, since it is not uncommon that overall disk regions of the patent's eyes are inclined, there arise cases where the rim of the cup cannot be detected by the above-described detection method.
It is possible to obviate the above-described problem if an operator designates three points on the disk region and effects analysis by using as a reference plane an inclined plane thus determined. In accordance with this method, however, there is a problem in that the data of the cups detected vary for each operator, and the data can be different on each occasion of analysis even for the same operator, with the result that the reliability and reproducibility of the results of analysis are poor.