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226 Walsh & Hoyt: Pulfrich PhenomenonMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteIn 1922, Pulfrich reported that when a small target oscillating in a frontal plane is viewed binocularly with one eye covered with a filter to reduce light intensity, the target appears to move in an elliptic path, rather than a to-and-fro path. When the filter is placed over the right eye, the rota...
227 Walsh & Hoyt: Other ProceduresMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteOther tests beyond a conventional office examination may be needed to establish the site of the pathology in the afferent visual system. Fluorescein angiography and indocyanine green angiography (ICG) may be necessary to identify retinal pathology. An electroretinogram (ERG), focal or maculoscope ER...
228 Walsh & Hoyt: Visual Field ExaminationMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteExamination of the visual field is one of the fundamental portions of the afferent system evaluation.A variety of visual field test procedures can be employed, including confrontation fields, the Amsler grid, the tangent (Bjerrum) screen, manual kinetic testing using a Goldmann perimeter, and automa...
229 Walsh & Hoyt: Visual-Evoked PotentialMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteUntil the early 1960s, the electroencephalogram (EEG) was the main technique available for clinical evaluation of electric activity of the human cortex. It was subsequently etermined that if the spontaneous occipital EEG was recorded while brief flashes of light were presented to an eye, changes wou...
230 Walsh & Hoyt: Other Retinal PotentialsMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteThere are several retinal potentials other than the ERG and EOG (e.g., early receptor potentials, oscillatory potentials, the scotopic threshold response) that can be measured under specific test conditions, but they are more commonly used for clinical research studies than for routine clinical eval...
231 Walsh & Hoyt: HistoryMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteAn examination of patients experiencing dysfunction of the afferent visual system begins with a history of the details of the visual loss. This thorough history is often the most important part of the evaluation, because it determines the initial strategy for differential diagnostic evaluation and e...
232 Walsh & Hoyt: Clinical ExaminationMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteClinical evaluation of the afferent visual system for each eye incorporates the items in Table 2.1, which can be performed in the office. This section presents a brief discussion of each component, with a more detailed discussion of several visual function tests (visual acuity, contrast sensitivity,...
233 Walsh & Hoyt: Pupillary ExaminationMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteExamination of the pupils is an essential part of the afferent ystem evaluation. Pupil size for each eye should be noted, as should the magnitude and latency of the direct and consensual responses to light and near stimulation. The presence of a relative afferent pupil defect (RAPD) is the hallmark ...
234 Walsh & Hoyt: Electrophysiologic TestsMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteFrequently, the physician is confronted with a patient who has unexplained loss of vision and an apparently normal fundus examination. Because electrophysiologic testing often provides diagnostic clues as to the etiology of the unexplained visual loss, it should be part of the neuro-ophthalmologic e...
235 Walsh & Hoyt: Photo Stress TestMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteThe differentiation between unilateral retinal disease and retrobulbar optic neuropathy may be aided using the photo stress recovery test described by Glaser et al. This test is based on the principle that visual pigments bleach when exposed to an intense light source, resulting in a transient state...
236 Walsh & Hoyt: Refraction and Visual AcuityMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteA thorough refraction is an essential part of all clinical neuro-ophthalmologic examinations. Identification of a previously undetermined refractive error, corneal pathology, or a subtle lens problem can prevent initiation of an expensive and time-consuming evaluation. It is essential to have the be...
237 Walsh & Hoyt: Contrast SensitivityMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteVisual acuity defines the smallest spatial detail that can be resolved for high-contrast stimuli, but it does not specify the responses of the visual system to objects of different sizes and contrasts. Measurement of the spatial contrast sensitivity function (CSF) is necessary to obtain this informa...
238 Walsh & Hoyt: Color VisionMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteA comprehensive discussion of color vision is beyond the scope of this chapter. Instead, we will limit our discussion of this subject to an overview of normal color vision and its underlying physiologic mechanisms, congenital and acquired color vision deficiencies, the use and interpretation of comm...
239 Walsh & Hoyt: StereoacuityMichael Wall, MD, University of Iowa, Department of Neurology and Ophthalmology; Chris A. Johnson, MD, Devers Eye InstituteStereoacuity requires good visual acuity in both eyes and normal cortical development. As such, stereoacuity can be helpful in establishing if a patient has visual loss from congenital amblyopia or monofixation syndrome, as well as verifying the extent of any monocular visual acuity loss.
240 Vestibular SymptomsMark S. Borchert, MD, University of Southern CaliforniaPatients with disorders that affect the vestibular system may complain of disequilibrium or unsteadiness, symptoms that reflect imbalance of vestibular tone.
241 Walsh & Hoyt: Pseudopapilledema Associated with Optic Disc DrusenMichael C. Brodsky, MD, Mayo Health SystemThe word drusen, of Germanic origin, originally meant tumor, swelling, or tumescence. According to Lorentzen, the word was used in the mining industry approximately 500 years ago to indicate a crystal-filled space in a rock. Drusen of the optic disc were first described clinically by Liebreich in 18...
242 Walsh & Hoyt: Morning Glory Disc AnomalyMichael C. Brodsky, MD, Mayo Health SystemThe morning glory disc anomaly is a congenital, funnelshaped excavation of the posterior fundus that incorporates the optic disc. It was so-named by Kindler because of its resemblance to the morning glory flower. Ophthalmoscopically, the disc is markedly enlarged, orange or pink in color, and may ap...
243 Walsh & Hoyt: Optic Disc ColobomaMichael C. Brodsky, MD, Mayo Health SystemThe term coloboma, of Greek derivation, means curtailed or mutilated. It is used only with reference to the eye. According to Mann, colobomas of the optic disc result from incomplete or abnormal coaptation of the proximal end of the embryonic fissure. Liebrich is credited with the first ophthalmosco...
244 Vertebral Artery and Its BranchesRobert A. Egan, MD, Providence Willamette Falls Medical CenterIn most normal persons, one VA arises on each side as the first branch of the subclavian artery.
245 Vertebrobasilar Arterial System and Its BranchesRobert A. Egan, MD, Providence Willamette Falls Medical CenterThe two VAs, the BA, and the two PCAs, constitute the posterior circulatory system of the brain.
246 Vertebrobasilar SystemRobert A. Egan, MD, Providence Willamette Falls Medical CenterFigure 39.47
247 Walsh & Hoyt: Abnormal Eye Movements and DementiaDavid S Zee, M.D., Professor of Neurology, Johns Hopkins University; David Newman-Toker, MD, PhD, Associate Professor, Departments of Neurology, Ophthalmology, & Otolaryngology, The Johns Hopkins University School of MedicinePatients with various dementing processes have abnormal eye movements, reflecting either disturbances in cerebral cortical structures or in other subcortical structures that may also be affected by that particular disease. Excessive errors on the antisaccade test, particularly when associated with a...
248 Walsh & Hoyt: Ocular Motor Syndromes Caused by Lesions of the ThalamusDavid S Zee, M.D., Professor of Neurology, Johns Hopkins University; David Newman-Toker, MD, PhD, Associate Professor, Departments of Neurology, Ophthalmology, & Otolaryngology, The Johns Hopkins University School of MedicineThalamic lesions are characterized by disturbances of both horizontal and vertical gaze. Conjugate deviation of the eyes contralateral to the side of the lesion (also called wrong-way deviation) may occur with hemorrhage affecting the medial thalamus. The reason for this contraversive deviation is u...
249 Walsh & Hoyt: The Smooth Pursuit SystemJames A. Sharpe, MD, FRCP(C) (1941-2013); Agnes Wong, MD, PhD, FRCSC, University of TorontoSmooth pursuit stabilizes the image of an object on or near the fovea during slow movement of the object or of the body. Smooth pursuit is needed to hold the eye on a stationary target during locomotion. When one views a target located off to one side during locomotion, smooth pursuit holds its imag...
250 Walsh & Hoyt: Ocular Motor Syndromes Caused by Lesions in the CerebellumDavid S Zee, M.D., Professor of Neurology, Johns Hopkins University; David Newman-Toker, MD, PhD, Associate Professor, Departments of Neurology, Ophthalmology, & Otolaryngology, The Johns Hopkins University School of MedicineClinicians are appropriately cautious in attributing eye movement abnormalities specifically to cerebellar dysfunction, because the brain stem is so frequently damaged in patients with lesions of the cerebellum. Likewise, brain stem lesions can produce a ""functional"" cerebellar lesion and correspo...
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