Evaluation of the retinal nerve fiber layer: descriptive or predictive?

For nearly a century, ophthalmologists have recognized that thinning of the retinal nerve fiber layer (rNFL) could be observed ophthalmoscopically in diseases of the optic nerve. Using high-resolution red-free fundus photography, Hoyt found slit-like rNFL defects that corresponded to visual field defects in glaucoma. Frisén extended these observations to multiple sclerosis, predicting the later discovery that axonal loss occurs in the retina without clinical bouts of optic neuritis. In measurement of the rNFL, red-free fundus photography has been superseded by more widely available, robust, and quantitative retinal imaging techniques, including Heidelberg retinal tomography, scanning laser polarimetry, and optical coherence tomography (OCT). Having emerged as the technique of choice in measuring the rNFL, OCT has shown that the degree of preoperative rNFL thinning reliably predicts whether vision will recover after surgery for pituitary adenoma. Such quantitative studies of the rNFL have the potential, therefore, of providing descriptive and predictive information that will be valuable in clinical care.