Ocular thrombosis: a hypercoagulable disease.

Q. What conditions comprise ocular thrombosis? CJG Ocular thrombosis includes central and branch retinal vein occlusion (CRVO), central retinal artery occlusion (CRAO), amaurosis fugax (AF), and non-­arteritic ischemic optic neuropathy (NAION), all of which are closely related to coagulation abnormalities. In the United States, branch and central retinal rein occlusions are the second most common retinal vascular diseases, after diabetic retinopathy [1]. In the population-­based Beaver Dam Eye study of 4,926 subjects, the prevalence of retinal venous occlusive disease was 0.1% [2]. In the Australian Blue Mountains Eye Study, the prevalence of retinal occlusive disease was 0.7% in persons aged 49 to 60 years and 4.6% in subjects older than age 80 years [3]. The incidence of CRAO is about .01%, in 60-­65 year old subjects [1]. The incidence of NAION is estimated to be .003% in men at age 50 [4]. In a prospective study in a Danish community of 481,000, the annual incidence of first AF episodes coming to medical attention was .0086% in men and .0062% in women [5]. In perhaps the majority of cases of a central retinal arterial occlusion (CRAO), a very small piece of atherosclerotic plaque from an ulcerated carotid artery lesion travels to and lodges in the retinal artery. This thrombus causes AF and/or frank CRAO, or, rarely NAION. There are also, however, a significant number of cases of these three conditions in patients with normal carotid arteries. Our institution has studied at least 40 such patients. These patients have a variety of reasonably common thrombophilias, including G1691A Factor V Leiden and G 20210A Prothrombin gene mutations, heritable high factor VIII, homocysteine and the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C mutations, and less commonly, the Lupus Anticoagulant-­Antiphospholipid antibody syndrome [6, 7]. It is highly important to diagnose CRAO and AF in patients who suffer retinal arterial events without evidence of carotid artery plaque, erosion, or rupture. Patients with AF, and less commonly, CRAO can be administered thromboprophylaxis with low–molecular weight heparin (Enoxaparin) or later warfarin (Coumadin, Bristol-­Myers Squibb) if necessary. In AF, thromboprophylaxis usually ameliorates the symptoms of transient monocular blindness. [8]. In patients with CRAO and/or AF, there is a very high risk of ischemic stroke if a thrombus travels to the brain instead of a retinal artery. Therefore, it is recommended that patients with CRAO or AF have a carotid and vertebral Doppler sonogram. If this assessment is negative for atherosclerotic …