How to Capture Disease Activity in the Longitudinal Follow-Up of Optic Neuropathies?

Optic neuropathy is a common neuro-ophthalmic diagnosis. Although it is often easy enough to recognize and anatomically localize in its typical forms, it is more challenging to precisely follow for any significant change over time. Many of the tools we use to evaluate and follow optic nerve function are psychophysical such as acuity and perimetry, and accordingly suffer from subjectivity and variability-related errors. The pupil is useful in optic nerve assessment, and although objectively judged by the physician, it is infrequently quantified, and thus less suitable as a long-term follow up marker. Imaging and electrophysiology provide objective metrics for optic nerve anatomy and physiology, but may be cumbersome, expensive, or demonstrate unfavorable sensitivity, specificity and variability across clinics and visits. There is no perfect or gold standard clinical measure of optic nerve function, and the clinician must rely upon different combinations of these tools in individual patients to reliably detec meaning visual change.