THE EFFECT OF PERIOPERATIVE EMBOLIZATION ON VISUAL FUNCTION IN PATIENTS UNDERGOING CAROTID ENDARTERECTOMY

Objectives: To investigate the effect of carotid artery embolisation d etected by transcranial Doppler (TCD) monitoring during carotid endart erectomy (CEA) on visual function. Design: A prospective study. Visual function was assessed by an independent ophthalmalogist. Materials: O ne hundred consecutive patients undergoing carotid endarterectomy.Meth ods: All patients underwent pre- and postoperative retinal fundoscopy and automated visual field analysis. Intraoperative emboli were detect ed by continuous TCD monitoring of the middle cerebral artery. Results : Preoperatively, six patients had fundoscopic evidence of silent reti nal embolisation, five patients had visible emboli associated with ama urosis fugax. Visual field analysis found no significant difference be tween ipsi- and contralateral eye scores. Only patients with occlusion s of major retinal vessels had clinically reduced visual function. Int raoperatively TCD identified embolisation in 83/91 of monitored operat ions.Postoperatively, ipsilateral visual field scores deteriorated whi le contralateral eye scores remained unchanged, however only one new r etinal embolus was detected. The incidence of TCD detected embolisatio n was not associated with a corresponding deterioration in postoperati ve visual function. Conclusions: (1) A group of patients can be identi fied who experience ''silent'' retinal embolisation prior to CEA. (2) Clinically significant retinal embolisation resulting from CEA is unco mmon. (3) CEA is associated with a deterioration in the visual field s cores for the ipsilateral eye compared with the contralateral eye but the mechanism for this small but significant deterioration remains unc lear.