The Wisconsin age-related maculopathy grading system.

A new system for grading age-related maculopathy is described and measures of reliability are reported. A number of characteristics of age-related maculopathy are graded in a semiquantitative fashion from stereoscopic 30 degrees color fundus photographs, using a grid to define subfields, standard circles printed on plastic to assess size and area, and a specially designed lightbox to allow better discrimination of subtle drusen. The degree of exact agreement achieved between two trained graders across a variety of lesions ranged from 67.1% for drusen size to 99.6% for geographic atrophy. Kappa scores ranged from 0.55 (for drusen confluence) to 0.95 for geographic atrophy. This system will be useful in epidemiologic studies and clinical trials.