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Show LETTERS TO THE EDITOR 181 species. The current clinical spectrum of B~rrelia burgdorferi infection includes acute and chrome cutaneous lesions (erythema chronicum migrans, acrodermatitis chronicum atrophicans), arthritis, carditis, orchitis, iritis, episcleritis, and intrauterine infection followed by fetal stillbirth or malformation. Neurologic manifestations have been grouped into primary, secondary, and tertiary forms by Dr. Andrew Pachner and Dr. Allen Steere. Periods of clinical latency of up to 10 years have been described in selected patients with Borrelia burgdorferi infection. Peripheral neuropathy, transverse myelitis, psychiatric disorders, demyelinating disorders, multiple sclerosis-like illnesses, cognitive dysfunction, and dementia constitute various clinical presentations of late secondary and tertiary Lyme disease. I propose, based on the model of syphilis, that temporal arteritis might be the Borrelia equivalent of meningovascular syphilis. Preliminary studies of several temporal artery biopsies with silver impregnation methods and in vitro cultures have yielded evidence of spirochetes in either blood or tissue in biopsy-documented cases of giant cell arteritis. Ophthalmologists diagnose and treat the majority of patients with temporal arteritis. I would like to call attention to my hypothesis and to the results of my preliminary clinical studies. It is my hope that additional patients from various areas of this country might be enrolled in this project. Two tubes of blood (one EDTA purple top tube and one red top tube of clotted blood) from each patient with biopsy-documented giant cell arteritis are all that is required. These can be mailed to me at room temperature via ordinary parcel post. Patient confidentiality can be maintained by labeling the blood tubes with the first three initials of the patient's last name followed by the first initial. I would be interested in studying blood from patients at any stage of the disease. Preliminary results will be available to the referring ophthalmologist at any time via telephone, and cumulative reports will be mailed to the participating ophthalmologists at monthly intervals. Alan B. MacDonald, M.D. Department of Pathology Southampton Hospital Southampton, NY 11968 Generalized Visual Field Constriction To the Editor: Generalized constriction of the visual field is considered to be a nonspecific finding with a number of possible causes. Among the etiologic considerations are glaucoma, retinitis pigmentosa, long-standing increased intracranial pressure, occipitallobe lesions with macular sparing, and nonorganic visual loss. Distinguishing the latter from organic causes can usually be accomplished with several well-known diagnostic ploys. The nonorganic constricted visual field can usually be shown to be "tunnel" rather than "funnel"-shaped by confrontation and/or by 1 m/2 m tangent screen testing. Goldmann perimetry usually demonstrates "bunching up" or actual crossing of isopters. The observation that a patient's ability to navigate about the office is much better than would be expected for the degree of visual field loss is also helpful. By each of these techniques, it can be demonstrated that visual loss is inconsistent and must have at least a component that is nonorganic. What is not documented is the actual extent of visual capacity. I have found an additional technique for evaluating such patients that can demonstrate intact vision in the peripheral field. At some point following the standard assessment of the visual field, the patient is asked a few neurologic review-of-systems questions, particularly involving coordination in the upper extremities. Then, by way of demonstrating such skills, the patient is asked to open and close the hands rapidly, tap thumb and forefinger, and tap the knees with the hands. It is important to maintain steady eye contact with the patient during these maneuvers; repeated encouragement and moving quickly helps. Then, the patient is instructed to perform finger-nose-finger testing in the usual manner employed for testing cerebellar function. With each repetition, the examiner's finger is moved to different parts of the visual field, varying from right to left in a random manner. To avoid using cues from proximal arm movement, both arms can be extended simultaneously but with the fingers of only one side wiggling to denote the target. Using this technique, it is usually possible to demonstrate an intact visual field out to the extreme periphery. Since the test is performed under JOi" NCII,o-ol'llthalll/ol, Vol. 7, No.3, 1987 182 LETTERS TO THE EDITOR binocular viewing conditions, the temporal but not the nasal fields are thus tested. This should be adequate in cases with bilateral constricted fields. The occasional patient with a unilaterally constricted field will need the good eye patched prior to such testing. Explaining that it will be necessary "to establish dark adaptation" in the normal eye seems to pass this off as reasonable. In my experience patients with nonorganic visual loss will invariably perform this test without difficulty. Those with true severe organic constriction may locate the target in the periphery but will only do so slowly and with difficulty. Such patients can be seen to either follow the examiner's arm out to find the target or will break eye contact and search the periphery. I eli" Neuro-ophthalmo/, Vol. 7. No.3, 1987 In patients with nonorganic loss of visual acuity it is sometimes possible to demonstrate, either by stereoscopic equivalent, by fogging the good eye, or by other means that vision is in fact 20/20. Such a demonstration tends to be more satisfying to physician and patient than simply showing inconsistencies among responses. The technique for visual field testing described here can give comparable support to the diagnosis of nonorganic visual field loss. Valerie Purvin, M.D. Midwest Eye Institute 1800 North Capitol Avenue Indianapolis, IN 46202, U.S.A. |
