Objective measurement of cortical and subcapsular opacification in retroillumination photographs

An image analysis system has been developed for the objective analysis of cortical opacification. Lens photographs are obtained using a Neitz CTR retroillumination camera. The images are digitized using an IBM-PC-based imaging system. We have developed a program, called OPAC, through which the computer analyzes the image using a circular grid consisting of 93 sectors. The program outputs the percent of lens area which is opaque. Ninety-eight photographs, previously classified by the Lens Opacities Classification System (LOCS II), were analyzed using OPAC as well as a manual, square-grid counting system (GRID). The results show a linear correlation between OPAC and GRID with a correlation coefficient of 0.94. The results obtained with OPAC are also linearly correlated with the LOCS II classifications.