A new analysis method for cataractous images taken by retroillumination photography.

Photographic data have been used to diagnose cataracts. In particular, retroillumination photographs are popular and useful owing to their clearness of whole images of crystalline lenses at a glance. A new procedure called grid method for the quantitative analysis of retroillumination photographs is proposed here. With this method a ratio of cataractous area to total area can be calculated by separating an image of a lens in grids, with a greater precision compared with the usual threshold method. Furthermore, based on a correlation check of the grid number and the resulting accuracy we determined that 25 grids is the optimal cutting for our grid method.