7. Lund VI, Harvey W, Meghji S, et al. Prostaglandin synthesis in the pathogenesis of fronto-ethmoidal mucocoeles. Acta Otolaryngol Stockh 1988;106:145-51. 8. Blake PY, Mark AS, Kattah I, et al. MR of . Am J Neuroradiol 1995;16:1665-72.

Pammal T. Ashwin Sajjad Mahmood William S.T. Pollock � Department Blackpool Victoria Hospital Whinney Heys Road Blackpool FY3 8NR, UK

Sir,

Ipsilateral proliferative diabetic in carotid stenosis Asymmetric is not common, with Fig. 1. picture of right eye showing preretinal haemorrhage reports of incidence varying from 5% to 10%.1 Although and panretinal laser photocoagulation scars. there is no universally specified classification to define for near. There was no pupillary defect and examination when asymmetry exists, the Diabetic Retinopathy Study of the anterior segments revealed bilateral early Group used the criteria of proliferative diabetic opacities. There was no corneal oedema, rubeosis or retinopathy in one eye, with neither proliferative nor anterior chamber flare. The intraocular pressures were 18 preproliferative changes in the fellow eye. Other authors2 mmHg either eye. Fundal examination showed have stressed that such asymmetry should be present for proliferative diabetic retinopathy in the right fundus, 2 years to exclude patients with diabetic retinopathy with disc new vessels and a fresh preretinal haemorrhage which develops at a slower rate in one eye to eventually inferiorly (Fig. 1). There were splinter haemorrhages near become symmetrical. Carotid stenosis is one of a number the disc, but no peripheral or mid-peripheral dot or blot of factors implicated in the development of asymmetric haemorrhages. In addition there were features of diabetic retinopathy, the eye with the worse retinopathy (arteriovenous nipping and being on the side contralateral to the more significant venous beading) in both eyes. The left fundus revealed stenosis. This phenomenon has been explained as being mild background diabetic retinopathy with a small due to the protective influence of the carotid stenosis on cholesterol embolus superotemporally (Fig. 2). There was the development and progression of diabetic no evidence of previous retinal vein occlusions or retinopathy. We report a more unusual case of unilateral chorioretinal scarring in either eye. Bilateral carotid proliferative diabetic retinopathy on the side ipSilateral bruits were detected, louder on the right than the left to the more severe carotid stenosis. side. She was commenced on aspirin 75 mg daily, and fundus fluorescein angiography was carried out which Case report confirmed right-sided retinal ischaemia. The arm to A 65-year-old woman with a 2 year history of non­ time was 14 s in both eyes. Choroidal perfusion insulin-dependent diabetes presented to the eye clinic in was normal. The patient was referred to the April 1998 with a history of slightly in the right eye for the past month. On further questioning she also complained of a wavy line developing across her vision on first getting up in the morning on opening her curtains. She also described two non-specific episodes of 'not seeing things properly' out of the right-hand side of her vision. She denied any periocular or discomfort. There was no history supportive of or transient ischaemic attacks. She had a 15 year history of for which she was being treated with bendrofluazide and amlodipine. She regularly attended the hospital diabetic clinic and described her current control as 'up and down'. She had recently been advised to lose weight and to cut down her smoking from 20 cigarettes a day. On examination, her uncorrected was 6/ 12, NI0 in the right eye and 6/9, NlO in the left eye, Fig. 2. Fundus picture of left eye showing mild background diabetic distance and near respectively, improving to 6/6, N5 retinopathy. Note the cholesterol embolus along the superior temporal: either eye with +1.00 Dsph for distance and +3.00 Dsph arteriole.

110 neurovascular clinic. Carotid Doppler/duplex scans, This case highlights the risk of severe carotid artery showed a 90% stenosis in the right internal carotid artery stenosis leading to, rather than preventing, the and 80% in the left. This was later confirmed on a development of ipsilateral proliferative diabetic magnetic resonance angiogram. There was also a retinopathy, particularly in patients with evidence of 'moderate' stenosis of the left external carotid artery. Her widespread ischaemia. resting was 150/74 mmHg, her electrocardiogram was normal, her cholesterol was marginally raised at 5.6 mmol/l. References In view of the lack of symptoms of cerebral transient ischaemic attack and given the degree of stenosis, it was 1. Dogru M, Ino-Ue M, Nakamura M, Yamamoto M. Modifying decided to defer carotid endarterectomy. Panretinal laser factors related to asymmetric diabetic retinopathy. Eye 1988;12:929-33. photocoagulation was carried out. Eight weeks following 2. Early Treatment Diabetic Retinopathy Study Group. the laser treatment to the right eye there was marked Classification of diabetic retinopathy from fluorescein regression of the new vessels. The right eye has remained angiograms. ETDRS report no. 11. Ophthalmology stable. In November 1999 she collapsed at home 1991;98:807-22. following an episode of light-headedness. A magnetic 3. Duker J, Brown G, Bosley T, Colt C, Reber R. Asymmetric resonance angiogram confirmed a 90% stenosis of the proliferative diabetic retinopathy and carotid disease. right internal carotid and 80% of the left side. She Ophthalmology 1990;97:869-73. underwent successful right carotid endarterectomy and 4. Browning D, Flynn H, Blankenship G. Asymmetric retinopathy in patients with diabetes mellitus. Am J is currently asymptomatic. There has been no Ophthalmol 1988;105:584-9. progression of the diabetic retinopathy in her left eye 5. Valone J, McMeel J, Franks E. Unilateral proliferative diabetic during her 2 year follow-up. retinopathy. II. Clinical course. Ophthalmology 1982;99:1362-6.

6. Moss SE, Klein R, Klein BEK. Ocular factors in the incidence Comment and progression of diabetic retinopathy. Ophthalmology Asymmetric diabetic retinopathy has been described in 1994;101:77-83. association with a number of risk factors including 7. Ulbig MRW, Hamilton AMP. Factors influencing the natural previous branch retinal vein occlusion, carotid artery course of diabetic retinopathy. Eye 1993;7:242-9. disease, complicated surgery, trauma, asteroid 8. Gay A, Rosenbaum A. Retinal artery pressure in asymmetric hyalosis and , whereas high , chorioretinal diabetic retinopathy. Arch Ophthalmol 1966;75:758-62. and optic atrophy are considered 'protective' factors.1,3-7 9. Valone J, McMeel J, Franks E. Unilateral proliferative diabetic retinopathy. I. Initial findings. Ophthalmology Carotid artery stenosis has usually been reported as 1981;99:157-61. being a protective factor against the development of l 3 S 9 10. Brown G, Magargal L, Simeone F, Goldberg R, Federman J, proliferative diabetic retinopathy , , , with isolated Benson W. Arterial obstruction and ocular reports of it acting as a risk factor? It presumably neovascularisation. Ophthalmology 1982;89:139--46.

protects the eye from proliferative retinopathy by 11. Furlan AJ, Whisnant JP, Keams TP. Unilateral visual loss in lowering retinal perfusion pressure. Venous stasis bright light: an unusual symptom of carotid artery occlusive retinopathy or low-flow retinopathy may develop with a disease. Arch Neurol 1979;36:675. tightly stenosed internal carotid artery. The ocular A.G. Rowlands ischaemic syndrome is found with severe ischaemia P. Palimar associated with ipsilateral common carotid artery Department of Ophthalmology stenosis or severe bilateral obstruction of the internal Warrington General Hospital carotid arteries.lO In our case, there was no suggestion of Warrington, UK the ocular ischaemic syndrome either clinically or on T.P. Enevoldson angiography to explain the development of proliferative Walton Centre for Neurology and Neurosurgery Liverpool, diabetic retinopathy on the same side as the severe UK stenosis. The other symptoms mentioned in the history of Mr P. Palimar, MS, FRCS, FRCOphth � this patient, i.e. the transient unilateral visual loss in Warrington Hospital Warrington bright light () and of feeling dizzy on first Cheshire WAS 1 QG, UK opening the curtains and seeing light in the morning are important symptoms suggestive of critical ischaemia of theeyes and/ or brain. The aetiology is believed to be due Sir, to metabolic impairment of photopigment regeneration l1 due to hypoxia. This may be of importance to this case Corneal perforation in chronic graft-versus-host disease in suggesting that a more global picture of ischaemia Sicca syndrome related to chronic graft-versus-host may be predictive of the likelihood of worsening of disease (GvHD) followir).g bone marrow transplantation diabetic retinopathy. While a certain degree of carotid has been well described. However, dry eyes leading to occlusionis protective, any further compromise may be a corneal melting with subsequent perforation in the risk factor. absence of infection is a rare complication of GvHD.

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