Hyperemic responses of the optic nerve head blood flow to chromatic equiluminant flicker are reduced by ocular hypertension and early glaucoma

We evaluated in ocular hypertension (OHT) and early glaucoma (EOAG) patients the optic nerve head (ONH) blood flow response (RFonh) to chromatic equiluminant flicker. This stimulus generates neural activity dominated by the parvo-cellular system. Eleven EOAG, 20 OHT patients, and 8 age-matched control subjects were examined. The blood flow (Fonh) at the neuroretinal rim was continuously monitored by laser Doppler flowmetry before, during, and after a 60-s exposure to a 4 Hz, red-green equiluminant flicker stimulus RFonh was expressed as percentage Fonh-change during the last 20 s of flicker relative to baseli Responses were collected at a number of temporal sites. The highest RFonh value was used for subsequent analysis. As compared to controls, both OHT and EOAG patients showed a decrease.