Acute Visual Loss 5 Cédric Lamirel , Nancy J

Acute Visual Loss 5 Cédric Lamirel , Nancy J. Newman , and Valérie Biousse Abstract Visual loss is a common symptom in neurologic emergencies. Although ocular causes of visual loss are usually identifi ed by eye care specialists, many patients appear in an emergency department or a neurologist’s offi ce when the ocular examination is normal or when it suggests a neurologic disorder. Indeed, many causes of monocular or binocular acute visual loss may reveal or precede a neurologic process. In this situation, a quick and simple clinical examination done at bedside in the emergency department allows the neurologist to localize the lesion and determine whether an urgent neurologic workup or further ophthalmologic consultation is necessary. Keywords Central retinal artery occlusion • Funduscopic examination • Optic neuropathy • Retinal emboli • Visual fi eld • Visual loss Acute vision changes typically precipitate emergency consultation. Although ocular causes are usually identifi ed by eye care specialists, many patients appear in an emergency department or a C. Lamirel , MD neurologist’s offi ce when the ocular examination Service d’ophtalmologie , Fondation Ophtalmologique is normal or when it suggests a neurologic disor- Adolphe Rothschild , Paris , France der. Indeed, many causes of monocular or binoc- e-mail: [email protected] ular acute visual loss may reveal or precede a N. J. Newman , MD • V. Biousse, MD () neurologic process. In this situation, a quick and Neuro-Ophthalmology Unit , simple clinical examination done at bedside in Emory University School of Medicine , Atlanta , GA , USA the emergency department allows the neurologist e-mail: [email protected]; [email protected] to localize the lesion and determine whether an K.L. Roos (ed.), Emergency Neurology, DOI 10.1007/978-0-387-88585-8_5, 95 © Springer Science+Business Media, LLC 2012 96 C. Lamirel et al. urgent neurologic workup or further ophthalmo- as “count fi ngers,” “hand motion,” “light percep- logic consultation is necessary [ 1, 2 ] . tion,” or “no light perception.” The Neuro-Ophthalmologic Color Vision Examination in the Emergency Department Color vision testing is important to localize the lesion to the optic nerve or to detect subtle visual Evaluation of visual function, examination of the changes when visual acuity is normal. Altered pupils and extraocular movements, and ocular color vision can be the only early sign of an optic funduscopic examination are all part of the rou- neuropathy. A simple way to test it at bedside in tine neurologic examination. They are particularly patients complaining of unilateral vision loss is important when the patient has visual symptoms, to present a bright red object to each eye and to or when the neurologic disorder involves the ask the patient to estimate the amount of “redness” intracranial visual pathways or is classically asso- in each eye [ 1 ] . Unilateral optic neuropathies will ciated with neuro-ophthalmic manifestations or produce red desaturation (dimmer or darker red) complications. Often, a detailed neuro-ophthalmic in the affected eye. A more formal and quantita- examination provides helpful clues regarding the tive way to test color vision is with Ishihara or mechanism of neurologic symptoms and signs Hardy Rand Ritter pseudoisochromatic color and guides the neurologist when making acute plates. management decision in the patient with visual complaints. The only tools needed are a near visual acuity card (but a magazine from the wait- Visual Fields ing room can be suffi cient), a bright red object, a bright light for external and pupil examinations, Visual fi elds are usually assessed in the emer- and a direct ophthalmoscope. gency department by confrontation methods, and can be of great value in helping localize the lesion. As for visual acuity, visual fi elds are tested Visual Acuity one eye at a time, with special attention directed to the horizontal and vertical axes of the visual Visual acuity is easily measured in cooperative fi eld. One eye is occluded and the patient is patients in the emergency department or in the instructed to count fi ngers presented within the neurologist’s offi ce. Each eye must be tested sep- central 30° by the physician while the patient arately and patients should wear their corrective looks at the examiner’s opposite eye or nose, and lenses (glasses or contact lens) during the exami- maintains fi xation. The patient must perform the nation. A near card (or even your name tag or a task equally well in all four quadrants. An asym- magazine) is good enough to test visual acuity. metry along the horizontal axis in one eye is most Patients over the age of 50 must wear their read- suggestive of optic nerve disease, whereas an ing glasses (or a +3 lens must be used). If visual abrupt change across the vertical meridian sig- acuity is improved when the patient looks through nals visual loss of intracranial origin. For more small holes made on a piece of cardboard (so- peripheral visual fi eld testing, fi nger movements called pinhole), the problem is refractive or ocu- may be used because these parts of the visual lar, and not neurologic in origin. This pinhole is fi eld are more sensitive to motion than shape. If also useful to estimate distance visual acuity the visual fi eld defect is within the central 10° when patients do not have their glasses. If the and too small to be detected by confrontation vision loss is so profound that the patient cannot testing, the Amsler grid is useful to test the cen- see anything on the near card, vision is measured tral visual fi eld at bedside. 5 Acute Visual Loss 97 Formal visual fi eld testing, such as Goldmann suggestive of pituitary apoplexy with chiasmal or automated perimetry, provides a more stan- and cavernous sinus compression. dardized examination, will reveal more subtle abnormalities, and can quantify the defects in order to follow disease progression. These tests Eye Movements are easily performed in an ophthalmologist’s offi ce once the patient is stable and able to Diplopia and ocular motility are discussed in cooperate. detail in Chap. 6. Some patients describe diplopia as “visual loss or blurriness” that resolves with covering either eye. True monocular or binocular Examination of the Pupils visual loss in association with abnormal eye movements should help localize the lesion (e.g., Pupillary examination in the dark and in the light to the orbital apex or to the sellar region). provides valuable information about the afferent and efferent visual pathways. Because both pupillary reactions to light and pupillary dilation in the Ocular Examination dark are examined, it is essential to turn the lights and Funduscopic Examination off to ensure that the level of light is low enough (which may be challenging in the emergency The ocular examination itself is usually the department or in an ICU). domain of the ophthalmologist, but careful pen- The search for a relative afferent pupillary light examination at bedside may reveal obvious defect (RAPD) is of great importance, particu- abnormalities of the anterior portion of the eye larly when visual loss is unilateral or asymmetric. (such as the cornea or lens) that could be the Indeed, the presence of an RAPD in the setting of cause of decreased vision or that could obstruct a normal-appearing retina is diagnostic of a an adequate view of the fundus [ 3 ] . Abnormalities unilateral or asymmetric optic neuropathy. of the ocular media suffi cient to cause severe Exceptions include severe retinal diseases, such visual loss usually result in a poor view of the as retinal vascular occlusions, and large retinal ocular fundus: “ If you can’t see in, the patient detachments, which are easily seen on fundu- can’t see out .” When media opacity is suspected, scopic examination. Corneal abnormalities, cata- the visual acuity should be tested without and racts, and macular disorders do not cause a with pinhole. Redness of the conjunctiva usually RAPD. indicates a problem involving the anterior seg- Unless the patient has a history of an ocular ment of the eye. Any ocular redness or pain asso- disorder (such as surgery or uveitis), anisocoria ciated with vision loss is usually an ophthalmic refl ects an efferent problem which may be either emergency and should prompt an immediate oph- a dilation problem (the smaller pupil does not thalmologic consultation. Corneal ulcerations, dilate well) or a constriction problem (the larger uveitis, and angle-closure glaucoma present with pupil does not constrict well). Poor dilation acute painful visual loss (Fig. 5.1 ). refl ects a lesion involving the sympathetic path- Examination of the ocular fundus is essential ways, such as from Horner syndrome, whereas in all patients complaining of visual loss. poor constriction refl ects a lesion involving the Pharmacologic dilation of the pupils with parasympathetic pathways such as a third nerve short-acting drops, such as a parasympathetic palsy, tonic pupil, or pharmacologic mydriasis. antagonist (tropicamide) and a sympathetic ago- Horner syndrome with acute visual loss points to nist (phenylephrine), allows the best and easiest the internal carotid artery, and may be the fi rst view of the optic nerve, macula, and blood ves- sign of a carotid dissection, whereas an acute sels. Phenylephrine should be avoided in patients third nerve palsy with visual loss is highly with severe systemic hypertension or malignant 98 C. Lamirel et al. localize the lesion to the eye and often reveal ocular emergencies. More rarely, however, the ocular examination does not explain the visual loss and an optic neuropathy or an intracranial process is suspected; sometimes, the ophthalmologist or emergency department physician identifi es a sign suggestive of a neurologic disorder, such as optic nerve head edema, bitemporal or homonymous visual fi eld changes, an efferent pupillary disorder, or abnormal extraocular movements.

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