Prognostic value of carotid ultrasound lesion morphology in retinal ischaemia: result of a long term follow up.

The importance of carotid plaque morphology in the prognosis of retinal ischaemia was investigated in a group of 165 patients followed for 2-7 years (mean 3.3 years). All patients had an initial carotid duplex ultrasound examination, with the results expressed in terms of the degree of stenosis caused by the lesion, and the lesion morphology. Lesions were divided into two groups, (a) combined homogeneous and simple heterogeneous structures, and (b) complex heterogeneous plaques. Complex heterogeneous plaques had a low echo pool within the lesion and/or an irregular surface pattern. A total of 144 (87%) patients were successfully followed, and of these 37 (26%) had cerebrovascular, cardiovascular, or retinal ischaemic events in the follow up period; 14 (10%) cerebrovascular accidents (eight fatal), 17 (12%) myocardial infarctions (10 fatal), two episodes of amaurosis fugax, and one of tunnel vision caused by a retinal embolus were recorded. There was no report of subsequent blindness. The percentage stenosis caused by the carotid lesions, although more severe in the vascular event group, was not significantly different between the groups. However, a significant difference (p < 0.1) was found in the morphological characteristics of the carotid lesions between the groups. Patients who suffered a vascular event in the follow up period had significantly more complex heterogeneous lesions compared with simple heterogeneous/homogeneous lesions, than those patients who remained alive and well. Carotid endarterectomy and antiplatelet therapy were equally distributed between the event and non-event groups. This suggests that the criteria for selection for treatment should be based on the lesion morphology as well as the degree of stenosis.