Evaluation of a reference set based grading system for retinal nerve fiber layer photographs in 1941 eyes

Purpose: To evaluate a reference set based grading system for retinal nerve fiber layer photographs. Methods: A total of 1941 retinal nerve fiber layer photographs (Canon non-mydriatic camera) were evaluated using a reference grading system. The reference system consists of 25 photographs of the retinal nerve fiber layer (Canon CF60U camera) of normals and patients with glaucoma. Each reference photograph represents a score for the visibility of the nerve fibers. Superior and inferior regions of the 1941 photographs of the sample of the normal population were matched separately to the references. Results: The standard deviation of between eyes differences was 2.76. This standard deviation compared reasonably to the standard deviation of 1.0 to 1.9 for real repeated measurements in an earlier study and indicates that the grading system has good accuracy in relation to the total range of 1 to 25. A clear relationship between photograph score and age was established. Conclusion: The photographic grading system demonstrated that it is viable in a different setting. Therefore, evaluation of retinal nerve fiber layer photographs with a photographic reference set might help ophthalmologists and technicians to integrate retinal nerve fiber layer photography in their clinical practice.