Abstract
Abstract: :
Purpose: To review the characteristics of patients presenting with atypical transient monocular blindness (TMB). Non-embolic TMB (neTMB) manifests itself clinically as episodes of brief, unilateral visual loss with positive visual symptoms (grey, white, lights), which differs from embolic TMB (eTMB). eTMB presents with negative blackout visual symptoms ("curtain effect" or altitudinal field loss). Methods: Retrospective case note analysis of all patients (n=51) diagnosed with neTMB, from neuro-ophthalmology clinic database, at Moorfields Eye Hospital, London. Patients with atheromatous or embolic aetiology were excluded. Results: 15 male & 36 female patients (n=51). 25 right eyes (49%) were affected. Mean age of onset was 37 years (range 14-77 years). Mean follow up period was 27 months (6-68 months). 6 patients had a previous history of migraine and 4 others had a family history of migraine. Headache following symptoms occurred in 8 patients (16%), and was associated with nausea or photophobia in only 2. Duration of symptoms <5, 5-20 and >20 minutes occurred in 24 (47%), 17 (33%) and 10 (20%) patients respectively. 26 (51%), 13 (25%) and 12 (24%) patients had grey, white/lights, and black visual symptoms respectively. Patients complained of a total blackout relatively infrequently (8%). A monocular grey field followed by a blotchy field recovery occurred in six patients (12%). Thirteen patients (26%) were treated with nifedipine, with reduction of frequency of symptoms in five (38%). 3 patients had persistent visual field loss. Conclusions: We report the largest series of neTMB. Headache is not a common feature in this series. Amaurosis fugax, retinal migraine and retinal vasospasm have previously described neTMB. It is uncertain whether pathophysiological mechanisms of migraine are ever implicated in TMB. 6 (12%) patients had a patchy or blotchy visual loss pattern suggesting choroidal rather than retinal circulation involvement. The response to nifedipine suggests that vasospasm underlies many or all of these attacks. Oral nifedipine is recommended in the subgroup with frequent symptoms. Clinicians should be aware of the clinical features, which distinguish eTMB from neTMB.
Keywords: neuro-ophthalmology: diagnosis • visual impairment: neuro-ophthalmological dise