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Editor,—Combined occlusion of the central retinal vein and the central retinal artery or a cilioretinal artery is unusual. There have been many previously reported systemic and ocular associations. The pathogenesis of this condition, however, is not established and remains controversial. Whether the venous obstruction or the arterial blockage acts as the initiating event is unknown. We describe a patient with combined central retinal vein occlusion (RVO) and cilioretinal artery occlusion occurring 6 weeks after starting hormone replacement therapy (HRT). We observed the evolution of the arterial occlusion. This suggests that the initiating event was the RVO.
A 46 year old patient presented with a 2 day history of decreased vision in the left eye noticed on waking. She reported no previous visual disturbances. She had been started on cyclical combined HRT 6 weeks before presentation. She was taking no other medication and had previously used the combined oral contraceptive pill with no adverse effects. She was a non-smoker. There was no past or family history of venous thromboembolism.
Visual acuities were right eye 6/5 and left eye 6/60. Right intraocular pressure (IOP) was elevated (22 mm Hg). There was a left relative afferent pupillary defect. Gonioscopy showed open angles. Blood pressure was 140/90 mm Hg. Pulse rate was 72 beats per minute and regular. There was no cardiac murmur and no carotid bruit. On the right there was pathological cupping of the optic disc and venous dilatation (Fig 1). Examination of the left fundus showed dilated, tortuous retinal veins in all four quadrants, with scattered retinal haemorrhages and a swollen, haemorrhagic optic disc. There was retinal whitening in the territory of a cilioretinal artery. No intra-arterial embolus was seen (Figs 1 and 2). She was diagnosed, on clinical grounds, with left combined central retinal vein and cilioretinal artery occlusion and right primary open angle glaucoma.
One week later, the cilioretinal artery had become narrow and irregular in calibre, with fractionation of the blood column (Fig 2). Two months after presentation, the perivenous haemorrhages and optic disc swelling had resolved, the calibre of the cilioretinal artery had returned to normal (Fig 2), and visual acuity had improved to 6/12.
She had no identifiable risk factors for venous thromboembolism. Laboratory studies consisting of full blood count, erythrocyte sedimentation rate, blood glucose, urea and electrolytes, liver function tests, serum protein, serum protein electrophoresis, serum lipids, angiotensin converting enzyme, rheumatoid factor, double stranded DNA, antinuclear antibody, antimitochondrial antibody, antismooth muscle antibody, antineutrophil cytoplasmic antibody, antineutrophil factor, anticardiolipin antibody, lupus anticoagulant, VDRL, TPHA, serum urate and thrombophilia screen including protein C, protein S, activated protein C resistance (Factor V Leiden), DNA analysis for a genetic variation in the prothrombin gene (prothrombin 20210A), thrombin time, antithrombin III, fibrinogen, factor VIII, and plasma homocysteine were normal. Chest x ray was also normal. Hormonal profile confirmed the patient's postmenopausal status.
She was managed with timolol 0.25% drops to the right eye. She was advised to discontinue the HRT since a causal relation with the retinal vascular disease could not be excluded. Low dose aspirin was commenced.
The pathogenesis of combined retinal venous and arterial occlusion is not established. Whether the venous obstruction or the arterial blockage acts as the initiating event is unknown.1 2Carotid artery disease has never been described as a cause of simultaneous retinal arterial and venous occlusion. Evolution of the arterial occlusion has been documented in this case. This suggests that the initiating event was the RVO, with subsequent stagnation of blood flow, elevation of intraluminal capillary pressure caused by a patent central retinal artery and ultimately cilioretinal artery occlusion secondary to the high intravascular pressure.
There have been many reported systemic and ocular associations of combined retinal arterial and venous occlusion including temporal arteritis,2 migraine, systemic lupus erythematosus,2 lupus anticoagulant, syphilis,2 optic neuritis,2 and various causes of retinal vasculitis. Relevant investigations excluded any of these as an underlying cause. Elevated IOP probably plays some part in the development of some central RVOs.3 Left IOP was normal at presentation but elevated IOP may have preceded the RVO. RVO has been reported in association with the oral contraceptive pill.4 In one study,5 five of 588 patients who had sustained RVOs were HRT users, but four of the five had other potential risk factors. With the ever increasing use of HRT, it is important that any possible adverse effects be reported. To the best of our knowledge, this is the first report of combined retinal arterial and venous obstruction associated with HRT.