Optic nerve head blood flow measurements in non-arteritic anterior ischaemic optic neuropathy

Purpose To determine whether a decrease in blood flow, measured by the Heid elberg retiinal flowmeter, can characterise a disc at risk and predict the occurrence of non-arteritic anterior ischaemic optic neuropathy (NAION). Methods Blood flow, volume and velocity were measured in the optic nerve he ads of 14 unaffected fellow eyes of patients with unilateral NAION, and com pared with those of the affected eyes and of the eyes of 7 age-matched heal thy controls. Results The affected eyes were found to differ from the unaffected eyes in all three haemodynamic parameters. Flow (measured in arbitrary units) is th e most important parameter to be taken into consideration. Blood flow was s ignificantly lower in affected than in unaffected eyes (upper rim, p < 0.05 ; lower rim, p < 0.025). It was also significantly lower in the unaffected eyes than in the healthy control eyes (p < 0.005, upper and lower rims), an d in the affected eyes than in the control eyes (p < 0.00005, upper and low er rims). Conclusion Decreased blood flow in the optic nerve head may indicate a risk for NAION and be considered a characteristic of the disc at risk.