Sir,

Retinal vascular occlusions in young adults are seen very infrequently and are generally associated with systemic disorders.1 With the increasing abuse of cocaine in Western countries, reports of medical complications are increasing. Besides the more common vascular complications described, such as myocardial infarction2 and cerebrovascular events,3 only one case of central retinal artery occlusion (CRAO) in an intravenous cocaine abuser, had until recently been reported.4 There have now also been two case reports of CRAO and central retinal vein occlusion in intranasal cocaine abusers.5,6

Case report

A 42-year-old man presented to casualty with a sudden painless loss of vision in his right eye 9 hours previously. He was not on any medication and was otherwise entirely fit and well with no history of migraine. He was a smoker of ten cigarettes a day for the past 20 years. He admitted to smoking ‘crack’ cocaine (more potent alkaloid form of cocaine) twice a week for the last 4 years, although he denied use of intranasal or intravenous abuse. He had smoked cocaine the previous evening. Visual acuity in the right eye was counting fingers at one metre, left eye 6/4. There was a right relative afferent pupillary defect. Examination of the anterior segments was unremarkable. Examination of the right fundus revealed diffuse retinal whitening and oedema in the posterior pole, with a foveal cherry-red spot and vascular attenuation, with sludging and segmentation of the blood column, consistent with a CRAO (Figure 1). No arterial emboli were seen. The left fundus was unremarkable (Figure 2).

Figure 1
figure 1

Fundus photograph of the right eye, showing retinal whitening and oedema in the posterior pole, with a foveal cherry-red spot and vascular attenuation, consistent with a CRAO. No arterial emboli are seen.

Full size image
Figure 2
figure 2

Fundus photograph of the left eye for comparison.

Full size image

Immediate treatment was instituted comprising 500 mg of acetazolamide intravenously, intermittent ocular massage and re-breathing into a paper bag for half an hour. Cardiovascular examination was normal with no carotid bruits, a regular pulse and no murmur audible.

Blood pressure, echocardiography, carotid ultrasonography, full blood count, erythrocyte sedimentation rate, fasting lipids and glucose, autoantibody screen including anti-cardiolipin antibody, protein S and C levels, antithrombin III level, Factor V Leiden, and blood homocysteine levels, were all normal. He was found to be sickle cell trait positive.

He has been reviewed 6 weeks later with no change in visual acuity. He has also been reviewed 2 months later and his visual acuity has improved to 6/18. His optic disc now appears pale. He has been strongly advised to stop smoking, both tobacco and in particular cocaine.

Comment

To the best of our knowledge this is the first case reported of CRAO associated with smoking cocaine in a previously healthy relatively young man. Previous case reports describe vascular occlusion following intravenous and intranasal cocaine abuse.

Inhibition of noradrenaline re-uptake by adrenergic nerve endings, direct vasoconstriction of vascular smooth muscle7 and increased platelet aggregation8 are among the invoked mechanisms of cocaine-related vascular complications. Systemically cocaine results in increased vascular tone, increased heart rate and blood pressure, and increased myocardial contractility.

CRAO, like cerebral infarctions, are typically found in older individuals and are often associated with systemic arterial hypertension.9 Arterial occlusions in the retina in older adults commonly occur secondary to embolisation from atheromatous plaques of the carotid artery.9 Arterial occlusions in younger patients are more commonly associated with migraine, trauma, cardiac embolic sources and various hypercoagulable states leading to thrombosis.1 The high prevalence of underlying systemic disease in these young patients necessitates a thorough evaluation to rule out potential life-threatening embolic and hypercoagulable conditions, thereby minimising additional systemic and ocular morbidity.1

Vasospasm may play a role in arterial occlusions in young adults. CRAO associated with migraine-induced vasospasm has been described. Myocardial infarctions in young adults after cocaine use have been attributed to vascular spasm and the dramatic increase in sympathetic tone.2 Arterial spasm may be induced by cocaine7 and may thus result in decreased ocular perfusion. In addition it is possible that severe hypertension from cocaine use could also have led to CRAO by causing fibrinoid necrosis within the vessels or haemorrhage under an atheromatous plaque within the central retinal artery.10

Hypercoagulable states including antiphospholipid antibody syndrome, Factor V Leiden, protein S

and C deficiencies, homocystinuria and hyperhomocysteinemia have all been excluded in our case. The only possible risk factor that has been established is his sickle cell trait status. We propose that smoking cocaine and his underlying sickle cell trait status have been the causative factors in this man’s CRAO.

In conclusion, cocaine abuse should be considered as part of the differential diagnosis for retinal vascular occlusion, especially in relatively young, otherwise healthy patients, in whom CRAO is extremely rare.