Transactions . nges, and who completelyrecovered in twenty minutes following inhalations of amylnitrite, a drug which promptly relaxes capillaries and lowersblood-pressure. Let us now consider briefly the explanation advanced byNettleship and Leber and in a modified form by Loring and Langdon: Alternating Transient Monocular Blindness. 805 Werner. Nettleship and Leber each believed that theabrupt diminution in size of the blood-stream from theinternal carotid to the ophthalmic, as well as the abruptturn made in changing its course, had a decided retardingeffect on the flow, and a narrowed lume
Transactions . nges, and who completelyrecovered in twenty minutes following inhalations of amylnitrite, a drug which promptly relaxes capillaries and lowersblood-pressure. Let us now consider briefly the explanation advanced byNettleship and Leber and in a modified form by Loring and Langdon: Alternating Transient Monocular Blindness. 805 Werner. Nettleship and Leber each believed that theabrupt diminution in size of the blood-stream from theinternal carotid to the ophthalmic, as well as the abruptturn made in changing its course, had a decided retardingeffect on the flow, and a narrowed lumen of the centralartery might be sufficient to block the stream enough toempty the vessels; then a change in relations would againoccur, and the blood with pressure behind and little or nonein front would surge forward and again fill the vessels. Loring and Werner seem to think that anything whichproduces a sudden fall in blood-pressure will tend to emptythe retinal arteries, and a return to normal pressure will. Fis- -1.—Increase of pressure due to 1 cc. of 1-lUOU adreiialiii chloride. once more fill them, the duration of the attack being decidedby the duration of the drop of arterial pressure. But changesin blood-pressure sufficient to produce such a profoundcirculatory change would surely produce more generalsymptoms and would not be confined to one or both of theretinal arteries alone. The writer recently had the oppor-tunity of studying a patient whom he had seen some monthspreviously with a blood-pressure of 230 and very decidedfundus alteration, edematous discs and blurred margins,advanced arteriosclerosis, and many superficial splashes ofretinal hemorrhage. In the interval the man had passedthrough an attack of paratyphoid fever. On recovery his 806 Langdon: Alternating Transient Monocular Blindness. blood-pressure was but 160, accompanied by weakness,vertigo and great cerebral discomfort. The edema of thedisc was completelj^ gone, the margins were quite clear, thereti
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