A comparison of two photographic systems for grading cataract.

Two different systems for classifying lens opacities were compared: the Lens Opacity Classification System version II (LOCS II) and the system developed at Johns Hopkins University. Using the two systems, slit-lamp photographs of the nucleus and retroillumination lens photographs of 100 eyes were graded. Each photograph was graded independently by three trained observers, and the time taken to grade the photographs was similar. Each system uses photographs to define the severity of nuclear opacity and nuclear color, and each showed good interobserver agreement (kappa statistic, greater than 0.6). The method of classifying cortical and posterior subcapsular opacity varied, and although interobserver agreement was acceptable in each system, it was somewhat higher with the Hopkins system. Because different standards and definitions are used to define severity with each system, there was some variation in the classification of individual photographs and corresponding differences in the proportion of photographs in each grade of severity. These data provide a useful cross reference for future comparison of studies using these systems.