An image analysis system for glaucomatous optic disc was developed. The key for optic disc measurement was to trace accurately the boundaries of the optic cup and disc. The 2-dimension measurement modality adopted was the heuristic boundary tracing method, and the 3-dimension measurement was performed by observation of the photographs, arbitrary selection of points, and automatic plotting and calculation. In order to measure accurately the optic disc in glaucoma follow-up, the authors made use of the cross correlation line by line scanning method, after proper correction of the photographs, to detect any positional shift in two photographs. By clinical verification, the 95% confidence criterion of normal optic cup boundary shifting was 1.7 pixels. The optic disc diameter of the disc images was over 200 pixels, and any shift over 2 pixels (1%) would have clinical significance, which was a high degree of precision.