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Show Journal of Clillical Ncuro-ophthallllology 7(1): 58-59,1987. Letters to the Editor Anterior Ischemic Optic Neuropathy Following Ocular Pneumoplethysmography To the Editor: With the now frequent usage of ocular pneumoplethysmography to evaluate suspected carotid occlusive disease, it is important for all those ordering this test to be aware of its potential risks. Although the test has an excellent safety record and no cases of permanent visual loss have been reported in association with it, the manufacturer recommends caution in patients with glaucoma, recent intraocular surgery, or vitreoretinal disease, due to the temporary distortion of ocular structures that the testing creates. Recently I observed a patient who developed acute anterior ischemic optic neuropathy immediately following ocular pneumoplethysmography. A 69-year-old white man had undergone ocular pneumoplethysmography without incident in 1982 for evaluation of scintillations in the right eye. He had several vasculopathic risk factors, including diabetes, hypertension, and hyperlipidemia, and had previously suffered a myocardial infarction. A second ocular pneumoplethysmography was performed in 1985 to evaluate several episodes of transient visual loss in the same eye; the test was interpreted as normal and was performed without complication. The patient did note moderate pain on generation of scleral vacuum pressure bilaterally, but subsequent evaluation of the test equipment showed no evidence of malfunction. One week later, he presented to the neuro-ophthalmology unit, stating that the inferior visual field of his right eye had been blurred since several hours following ocular pneumoplethysmography. Examination revealed a corrected acuity of 20/40, with an afferent pupillary defect, superior disc swelling (Fig. 1), and an inferior altitudinal visual field defect in the affected eye; no retinal emboli were present. An evaluated erythrocyte sedimentation rate of 50 mm/h prompted corticosteroid therapy and a temporal artery biopsy, which was negative. Whi~ft/~~~ patient was ta:ken off medication his visual acuityirnproved to 20120, but the field defect has persisted. 58 © 1986 Raven Press, New York FIG. 1. Superior disc swelling in the affected eye of a patient who underwent ocular pneumoplethysmography, Anterior ischemic optic neuropathy is the result of reduction in the gradient of optic nerve head perfusion pressure to intraocular pressure, possibly associated with a structural disc predisposition (1,2). Most cases are probably related to a narrowing in the anastamotic vascular network supplying the disc, but acutely raising intraocular pressure may also produce disc ischemia. Ocular pneumoplethysmography elevates intraocular pressure to 110-140 mm Hg for 3-5 s, with gradual return to normal over 30 s (4). Although normal eyes tolerate this situation without difficulty, it is conceivable that in eyes with circulatory compromise, this insult could tip the balance toward disc infarction. In the patient group referred for suspected carotid disease, a significant percentage are likely to have such compromise in the disc vascular supply, and some may actually be in the initial phase of the "stuttering" progressive form of anterior ischemic optic neuropathy. Although this case may well have demonstrated disc infarction irrespective of testing, opthalmologists, vascular surgeons, and neurologists alike must consider that ocular pneumoplethysmography may rarely contribute to the development of anterior ischemic optic neuropathy. Anthony C. Arnold, M.D. Jules Stein Eye Institute Los Angeles, CA |