Exercise-Induced Vasospastic Amaurosis Fugax FREE

Amaurosis fugax is characterized by a sudden, monocular, painless, temporary visual loss due to a hypoperfusion of retinal circulation. Some of the more frequent causes include atheromatous disease of the internal carotid or ophthalmic artery, vasospasm, optic neuropathies, giant cell arteritis, angle-closure glaucoma, increased intracranial pressure, orbital compressive disease, a steal phenomenon, and blood hyperviscosity or hypercoagulability.¹ Vasospasm may account for many cases of unknown cause.^1- 4 Amaurosis fugax due to exercise-induced vasospasm has been described only once, in 1989 by Imes and Hoyt.³ They described 6 healthy young adults who experienced visual loss precipitated by exercise. Three of them had monocular visual loss.

Exercise-induced visual disturbances not due to a hypoperfusion of retinal circulation include pigmentary glaucoma attacks, which may be painless,⁵ Uhthoff symptom after optic neuritis,⁶ and unformed hallucinations secondary to occipital lobe tumors.⁷ We describe 3 more patients with exercise-induced monocular transient visual loss, probably caused by vasospasm.

For 5 years, a 65-year-old man experienced recurrent exercise-induced transient monocular blindness. Visual symptoms consisted of a rapid progressive visual field constriction in his right eye. If the patient did not stop exercising, complete monocular blindness would occur. The events lasted from 30 seconds to 3 hours. They regularly appeared during heavy sport activities such as jogging or biking. During the 5 years, the frequency and strength of the attacks continuously decreased. The patient was in excellent health, had participated in sports regularly since his youth, and had no coronary risk factors. He had no history of migraine. He underwent an extensive work-up that included a neuro-ophthalmologic examination (with a gonioscopy), computerized visual field testing, visual-evoked potentials, a general and cardiovascular clinical examination, echocardiography, Holter monitoring, magnetic resonance angiography, and transcranial and transorbital Doppler and duplex ultrasonography. The results were normal. Blood evaluation included a complete blood cell count, blood chemical analyses, blood coagulation studies, and tests for thyroid function, erythrocyte sedimentation rate, antinuclear antibodies, cryoglobulins, syphilis, Lyme disease, and anticardiolipin antibodies. Because the patient was regularly able to provoke such episodes by climbing stairs, we had the opportunity to examine the patient several times during an attack. We could use fundus photography to observe and document the occlusion of the right central retinal artery (Figure 1). A Doppler ultrasonographic study during an attack showed a transient stopping of blood flow in the central retinal artery. We never observed a relative afferent pupillary defect during an attack. Treatment with aspirin or nifedipine had no effect.

A 40-year-old physician saw us because of a single attack of a hemianopic temporal scotoma in the left eye that had occurred during heavy physical activity. The episode lasted about 30 minutes. By covering 1 eye, he noticed that the defect was truly monocular. He had a history of migraine and had experienced headaches or stomachaches several times after heavy bodybuilding. He had undergone a work-up by internal medicine specialists for the stomachaches, which were diagnosed to be of vasospastic origin. Treatment with aspirin before sports participation reduced the degree of the symptoms. Results of a neuro-ophthalmologic examination and kinetic perimetry were completely normal. Because of the patient's history of chronic exercise-induced migraine and stomachache, the ocular symptoms were considered by exclusion also to be caused by vasospasm, and no further examinations were carried out.

For 14 years, a 45-year-old man experienced an exercise-induced transient "graying out" in his right eye lasting from 30 seconds to 15 minutes. Covering 1 eye confirmed that the symptoms were monocular. Results of a neuro-ophthalmologic examination, including a gonioscopy, were normal. Because this patient too was able to provoke such episodes by climbing stairs, we were able to examine him several times during an attack. We did not see any fundus abnormalities, possibly because stopping exercise resulted in a rapid recovery of visual acuity. However, immediate repeated automated perimetry after an attack showed a reproducible mild constriction of the visual field in his right eye. The left eye was always asymptomatic. A repeated intake of nifedipine resulted in the successful prevention of visual symptoms and a normal right automated perimetry finding after exercise. He had a history of thrombosis of the left superficial femoral artery. At the time of the examinations, the patient was not taking any medication. He had been smoking intermittently since he was a young adult. He had no history of migraine. The same blood work-up as in case 1 was performed, and results were found to be normal. Stress electrocardiographic findings were normal. Results of transcranial and transorbital Doppler and duplex ultrasonography were normal except for a slight hypoplastic right vertebral artery. Further work-up was refused by the patient.

Vasospasm is a recognized cause of amaurosis fugax^1,3 and also occurs in elderly patients.² Associated conditions include migraine, cluster headache, temporal arteritis, polyarteritis nodosa, and eosinophilic vasculitis.

Our 3 patients had exercise-induced monocular attacks, probably caused primarily by vasospasm. They illustrate the variety of transient monocular visual symptoms and findings that occur with exercise. Our first patient experienced rapid progressive visual field constriction. If exercising was not stopped, complete monocular blindness would occur. Anophthalmoscopy revealed a transient central artery occlusion (Figure 1). Our second patient noticed a hemianopic temporal scotoma in his left eye. The third patient described the visual loss as "graying out." Computerized perimetry performed immediately after an attack revealed an ipsilateral mild peripheral visual field constriction. In contrast to the 6 cases described by Imes and Hoyt,³ one of our patients with exercise-induced vasospasm had a late onset at age 60 years. Therefore, we conclude that vasospasm may also occur in elderly patients with a recent onset of exercise-induced amaurosis fugax.

Vasospastic amaurosis fugax is presumed to be caused by a vasospasm or reduced arterial flow.^2,4 Vasospasms could be caused by a vessel hypersensitivity to certain vasoconstrictors released during physical exercise or by an inappropriate high release of such mediators (eg, catecholamines, endothelin-1, or neuropeptide Y). Winterkorn et al⁴ reported a successful treatment with calcium channel blockers. In our first patient, neither aspirin nor the calcium channel blocker nifedipine was able to reduce the severity of the attacks. Our second patient was able to reduce the stomachaches by taking aspirin before performing sports. Because he had had only 1 attack involving the visual system and was comfortable with aspirin intake, calcium channel blockers were not tried. In our third patient, nifedipine could successfully prevent attacks.

To our knowledge, this is the first report showing that the calcium channel blocker nifedipine may be effective in certain patients with exercise-induced vasospastic amaurosis fugax.

Corresponding author and reprints: Daniel S. Mojon, MD, Department of Neuro-Ophthalmology and Strabismus, Kantonsspital, 9007 St Gallen, Switzerland (e-mail: daniel.mojon@kssg.ch).