STUDY OF NYCTHEMERAL VARIATIONS IN BLOOD PRESSURE IN PATIENTS WITH NON-ARTERITIC ANTERIOR ISCHEMIC OPTIC NEUROPATHY

Abstract

Objective: Non-arteritic anterior ischemic optic neuropathy (NAAION) is the most common acute pathology of the optic nerve in patients over 50 years of age and loss of vision is irreversible in the vast majority of cases. The role of nocturnal arterial hypotension in the occurrence of NAAION remains a topic of debate. Indeed, studies on this subject are rare and the results contradictory. In this study, we ubject the nychthemeral variations in blood pressure (BP) in a large cohort of patients with acute NAAION to determine the presence and extent of nocturnal arterial hypotension in this population, and thus determine whether nocturnal arterial hypotension could be involved in the pathophysiology of NAAION Design and method: BP was recorded for 24 h (ambulatory blood pressure monitoring, ABPM) in 65 patients with acute NAAION. Three definitions of nighttime periods were used: definition 1, 1 a.m.–6 a.m.; definition 2, 10 p.m.–7 a.m.; and definition 3, 10 p.m.–8 a.m. For each of these definitions, patients were classified according to the value of nocturnal reduction in BP into dippers (10–20%), mild dippers (0–10%), reverse dippers (< 0%), and extreme dippers (> 20%). Results: The proportions of dippers, mild dippers, reverse dippers, and extreme dippers varied significantly depending on the definition chosen. We found the highest number of patients with extreme dipping (23%) when using the strictest definition of nighttime period (definition 1, 1 a.m.–6 a.m.), as compared with 6.2% and 1.5% for the other definitions, respectively. Overall, 13 of 33 patients without known systemic hypertension (39%) were diagnosed with hypertension (systolic and/or diastolic hypertension) after ABPM. No risk factor for NAAION was associated with the extreme-dipping profile. Finally, the prevalence of systemic hypertension was high (69%). Conclusions: In our population of patients who had an episode of NAAION, the proportion of extreme dippers was higher than that usually found in the literature. The definition of the nighttime period used in this study had an impact on the proportion of extreme dippers and might probably explain the contradictory results from the few studies on this ubject.