Cigarette smoking is associated with glaucoma. Nicotine from cigarette smoking is known to produce hemodynamic changes. We studied the effect of nicotine on the ophthalmic artery flow velocity using transcranial Doppler ultrasound to measure noninvasively the Peak (systolic) flow velocity (VP), mean-envelope flow velocity (VM) and end-diastolic flow velocity, as well as using a laser Doppler flowmeter on the finger blood flow of the finger prior to and after administration of 2-4 mg nicotine in a gum base. In a pilot project a group of 18 glaucoma patients and 8 normal subjects were tested with nicotine, and another group of 11 glaucoma patients were tested with placebo. VP, VM, and systolic blood pressure were significantly increased while finger blood flow was significantly decreased when comparing the nicotine-tested glaucoma group with the placebo-tested group (P = 0.02074, 0.01479, 0.02185, and 0.04209, respectively). The nicotine-tested group of normals also showed significant changes in VM, systolic blood pressure, and finger blood flow compared to a placebo group. The responses to the small doses of nicotine used in this study (approximately one-third that of cigarette smoking) were not significantly different between the glaucoma and the normal groups.