Advances in optic nerve head analysis in glaucoma.

Assessment of the optic nerve head for structural changes is critical for the detection of glaucoma and for following progression in patients with established glaucoma. Qualitative optic nerve analysis can be obtained via methods such as disc drawings and stereo disc photography. However, these methods are limited by significant interobserver and intraobserver variability. Disc photographs can also vary greatly according to the camera angle, photographic technique, lighting, and magnification. The need for accurate, reproducible, and quantitative, cost-effective techniques of assessing the optic disc and appreciation of the limitations of subjective clinical observation stimulated the development of new technologies.