24-hour blood pressure monitoring in patients with anterior ischemic optic neuropathy.

OBJECTIVE

To define parameters of ambulatory diurnal blood pressure in patients who had experienced anterior ischemic optic neuropathy (AION) in a case-controlled study.

PARTICIPANTS AND METHODS

Twenty-four patients with AION and 24 control subjects who were matched for age, gender, medical diagnoses, and medications underwent ambulatory automated blood pressure monitoring for 24 hours.

RESULTS

The overall diurnal pattern of blood pressure appeared to be normal in all subjects, showing lower blood pressures at night than during the day, an overnight nadir, and an ascending blood pressure curve in the morning to reach daytime levels. Also, patients with AION did not differ from control subjects with respect to the nighttime diastolic nadir or daytime peak systolic blood pressure. However, during the daytime, patients with AION had lower mean systolic and diastolic blood pressures than did matched control subjects. The widest difference between their blood pressure curves occurred after awakening in the morning, when patients with AION had a less steep and more irregular rise of blood pressure. Patients who had signs of vertebrobasilar insufficiency in addition to AION had lower mean diastolic blood pressure during both daytime and nighttime and a lower minimum daytime diastolic blood pressure.

CONCLUSIONS

On ambulatory measurements of diurnal blood pressure, patients with AION consistently had a lower mean blood pressure than did control subjects and a lag in the usual rise in blood pressure in the morning to meet increasing daytime demands for perfusion. Chronic hypoperfusion of small end-arterial vessels that supply the optic nerve head may predispose to AION, and may be caused by relative hypotension owing to overtreated hypertension or to abnormal vascular autoregulation. Internists should be asked to monitor blood pressure carefully when treating hypertensive patients who are at risk for AION, to avoid hypotension, especially on awakening in the morning.