Abstract
Abstract: :
Purpose: To evaluate the changes in blood flow (F) measured at the neuro-retinal rim of the optic nerve in response to luminance (l-fl) and chromatic (c-fl) flicker in normal subjects, patients with ocular hypertension (OHT) and patients with early glaucoma (EOAG). Methods: F was continuously measured at 2-3 sites (150 µm diameter) of the temporal neuro-retinal rim by laser Doppler flowmetry before, during and after 60 sec exposure to a 15 Hz green l-fl and a 4 Hz, red-green equiluminant c-fl stimulus (30° field). Fifteen EOAG, 27 OHT and 12 age-matched control subjects were examined. The flicker-induced change in F (RF) was determined from the average value of F during the last 20 sec of flicker relative to the average value of 20 sec of pre-flicker F. In each subject, the highest RF was used. Results: In control subjects, RF was 43 ± 7%(se) for l-fl and 24 ± 3%(se) for c-fl. In OHT and EOAG patients, RF was attenuated by 44% and 68% compared to the values in the controls for l-fl (p<0.01). For c-fl, this attenuation in RF amounted to 50% in OHT and 33% in EOAG (p < 0.05). Conclusion: Luminance and chromatic flicker-evoked RF are significantly reduced in OHT and EOAG patients compared to normal subjects, suggesting a loss of vasodilatory activity at the optic nerve in these conditions.
Keywords: 498 optic disc • 331 blood supply • 356 clinical (human) or epidemiologic studies: systems/equipment/techniques