Many patients report eye strain, deep ocular pain, or a heavy sensation in the head — yet standard examinations reveal no abnormalities. This "invisible mismatch" may reflect fluctuations in autonomic tone and ocular perfusion that conventional static measurements cannot capture.
This presentation proposes using the low-frequency (LF) component of retinal blood flow, measured continuously via Laser Speckle Flowgraphy (LSFG), as a real-time autonomic state marker. LF shifts with time of day, fatigue, and stress — lower under sympathetic dominance, higher under parasympathetic dominance — and is interpreted here as a momentary "state" rather than a fixed trait.
The central hypothesis is that the same flicker stimulus produces different blood flow responses depending on the pre-stimulus LF state. The recovery phase after stimulation is particularly telling: healthy autoregulation maintains elevated flow, while dysfunction may cause a sustained drop, potentially indicating ischemia.
If validated, this LF × flicker protocol could serve as a quantitative biomarker extending beyond ophthalmology into neurology, neuroscience, and systemic medicine.