Subtypes of transient monocular blindness and subsequent risk of vascular complications

Background and Purpose: Little is known about different varieties of transient monocular blindness (TMB) in relation to the subsequent occurrence of vascular outcome events. Very few studies have addressed the prognostic value of the form of the attack in patients with TMB. To try and distinguish benign and hazardous symptoms of TMB, we studied the prognosis of different subtypes of TMB in terms of subsequent vascular complications. Methods: We analysed the characteristics of transient monocular loss of vision, vascular risk factors, and vascular events during follow-up in patients with TMB, who were recorded in the Royal Victoria Infirmary, Newcastle, United Kingdom (n = 137) or were entered into the Dutch TIA Trial (n = 185). The mean follow-up period was 5.0 years. The attacks were categorized in different 'patterns'. These patterns were related to the occurrence of (1) the combined event of vascular death, stroke or myocardial infarction and (2) cerebral infarction (fatal or non-fatal). Results: Patients with attacks of blurred vision had a more than twofold risk of vascular outcome events than patients with blackened vision, complete or in part [hazard ratio (HR) 2.3; 95% confidence limits (CL) 1.2-4.5]. Involvement of only a part of the visual field of one eye during the attack (instead of complete loss of vision) carried a lower risk (HR 0.4; 95% CL 0.2-0.9). Conclusion: Our findings suggest a relation between different types of TMB and outcome, but this needs to be validated in a subsequent cohort.