Correlation of smoking history with hearing loss.

To the Editor.— Vascular insufficiency of the cochlear organ is the predominant cause of progressive hearing loss that occurs with age in our society. Smoking reduces blood supply by (1) vasospasm induced by nicotine, (2) atherosclerotic narrowing of vessels, and (3) thrombotic occlusions. Vasospasm induced by smoking causes enlargement of the normal blind spot and reduced threshold of differential brightness. Visual perception is additionally depressed by the levels of carboxyhemoglobin commonly found in the blood of smokers, a hypoxic effect superimposed on the reduced blood supply. Serum cholesterol, triglyceride, and unesterified fatty acid levels are increased in smokers, predisposing to atherosclerosis. Diabetics who smoke have a 50% greater incidence of detectable leg atherosclerosis than do nonsmoking diabetics. Platelet adhesiveness is increased in smokers, predisposing to thromboses, and decreased platelet survival is demonstrable in vitro after smoking. Arterial thromboses (coronary, cerebral, retinal, peripheral) are up to three times as frequent in