To the Editor.\p=m-\Arcus senilis is an annular infiltration of lipid material in the periphery of the cornea and is a natural consequence of aging. Bilaterality is the hallmark of this finding, which is seen in 60% of people between the ages of forty and sixty, and is virtually always present by eighty years of age.1 We wish to report unilateral arcus senilis in a patient who had contralateral internal carotid artery occlusive disease.Report of a Case.\p=m-\This 85-year-old man was seen at the Bascom Palmer Eye Institute for progressive visual loss extending over a five-year period. He also had experienced numerous episodes of amaurosis fugax in the left eye for one year. During these episodes, which would last from one to three minutes, he had no light perception in the left eye. There were no associated symptoms, such as paresthesias or weakness. He had been in good health otherwise, and past history and family history were both unremarkable. Fig 1.-Unilateral arcus senilis on the right.He was an alert, well-oriented octogenar¬ ian. His blood pressure was 140/85 mm Hg, and pulse was 80 and regular. A very harsh, high-pitched, systolic bruit was heard over the left common carotid bifur¬ cation. The heart, lungs, and abdomen were normal. Inspection of the eyes showed a marked unilateral arcus senilis of the right eye (Fig 1). Visual acuity was 20/70 in the right eye and 20/25 in the left. Visual field testing showed nasal field defects in both eyes, and ophthalmoscopy revealed glaucomatous cupping of the optic disks. In¬ traocular pressure was 23 mm Hg in the right and 26 mm Hg in the left. Pupillary reactions were brisk, and ocular motility was normal.The diagnosis of chronic, open angle glaucoma and left internal carotid artery occlusive disease was made. The patient was treated with eye drops containing 2% pilocarpine, and during the following year he had only infrequent episodes of amauro¬ sis fugax.Two years later he died suddenly of a myocardial infarction. Autopsy revealed marked, generalized atherosclerosis. A large plaque virtually occluded the lumen of the left internal carotid artery, while the right was patent (Fig 2). In addition, the left middle cerebral artery was almost totally occluded at a point 2 cm from the junction with the internal carotid.Comment.-Unilateral arcus senilis has not been reported in association with carotid occlusive disease, to our knowledge. The arcus in this patient's right eye was striking, and its ab¬ sence in the left was a diagnostic clue to the atheromatous involvement on that side. One can postulate that the left cornea was protected by the homolateral reduction in flow so that an arcus did not develop. A related phenomenon is the occurrence of uni-Fig 2.-Large atheromatous plaque occluding left internal carotid artery. lateral hypertensive or diabetic retinopathy in patients who have contralateral carotid occlusive disease.-This is most striking in patients with ma¬ lignant hypertension where papilledema, cotton wool patches, and arteriolar narrowing are seen on the...