Much work remains to be done to establish the clinical usefulness of the RFI for early diagnosis and treatment guidance. The discoveries obtained by functional optical imaging of the neocortex in the last 15 years and the recent RFI studies of the eyes of normal subjects and patients with diabetic retinopathy, glaucoma, and age-related macular degeneration suggest that functional optical imaging of the retina is likely to become a multi-modality powerful clinical tool.