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Quick Consult: Symptoms: Flashes of Light, Shadow in Vision

Wiler, Jennifer L. MD, MBA

doi: 10.1097/01.EEM.0000413161.00679.95
Quick Consult
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A 57-year-old man presents to the ED with complaints of floaters, flashes of light, and a “shadow” in the vision of his right eye. He denies pain, red eye, and trauma to the affected eye. He has no ocular complaints in his left eye.

He admits to being nearsighted since he was 9 when he began wearing glasses. He has no history of previous ocular surgery, nor a family history of eye problems. The photograph shows what is seen on his dilated eye exam.

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Quick Consult: Diagnosis: Retinal Detachment

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Retinal detachment is an eye condition in which the retina detaches from the underlying retinal pigment epithelium. This ophthalmologic emergency is vision-threatening, and requires prompt identification in the emergency department.

The eye is a complex organ that translates light patterns into neural impulses sent via the optic nerve to be interpreted by the cerebral cortex into visual images. The retina (from Latin rēte, meaning net) icomposed of a thin layer of photosensitive cells that lines the inner layer of the eye, which is primarily responsible for sight.

The vitreous humour is a clear colorless jelly that fills the posterior chamber of the eye and helps to support the retina. It allows visible light to pass without scatter, and comprises nearly 80 percent (4 ml) of the globe. The retina is made up of eight layers from the vitreous to the retinal pigment epithelium: internal limiting membrane (i.e., Müller cell footplates), nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer (in the macular region also known as the Fiber layer of Henle), outer nuclear layer, and the photoreceptor inner/outer segments.

The human retina contains approximately 130 million rods and seven million cones, which are the unique photoreceptor cells of the eye. The macula is a yellow pigmented 6 mm diameter region near the central part of the retina. The central portion of the macula is a 1.5 mm diameter pit called the fovea, which contains the largest concentration of cone cells, and is responsible for high-resolution vision. The retina is developed at approximately nine months gestation, but the macula does not mature until a child is 15 to 24 months old. (Vitreoretinal Disease: The Essentials. Stuttgart, NY: Thieme; 1999.)

Occasionally due to trauma or injury, a tear or break occurs in the retina when collapse and detachment of the vitreous humor causes traction on the retina. This allows for vitreous fluid to trickle under the retina and peel it away from its adherent tissue base (like a bubble under wallpaper). Retinal detachments are fairly common, developing in five to 12 per 100,000 persons per year. (Retinal Detachment: Diagnosis and Management. Benson WE. Philadelphia: Lippincott Williams & Wilkins; 1998.)

Other conditions that increase the risk of a retinal detachment include cataract removal (aphakia 2%), extreme nearsightedness (high myopia >6 diopters; 5% risk), and complicated cataract removal with vitreous loss (10% increased rate). Jewish ethnicity and participation in certain high-velocity sports including bungee jumping and boxing are known to increase the risk of retinal detachment. Nearly one-fifth of patients with a retinal detachment develop a detachment in the other eye.

Patients may complain of flashes of light (photopsias), floaters (may occur as a “shower of black spots” or “cobwebs”), a curtain or shadow coming down over the visual field, visual “waves” (metamorphopsia), central or peripheral vision loss, and visual changes that vary with head position. When the vitreous gel separates from the retina, mechanical traction stimulates the retinal tissue and causes the release of phosphenes, mimicking the sensation of light.

Patients with retinal detachment may present with a history of trauma or have no inciting event. Retinal detachment has three distinct forms: rhegmatogenous, exudative, and tractional. Differentiation between these types is not typically important to the emergency physician except to know that the etiology of each differs. Rhegmatogenous retinal detachments can be caused by injury; exudative by neoplastic process, inflammatory disease, congenital abnormality, or vascular compromise; and tractional by tearing from tethering of fibrocellular bands from proliferative diabetes, toxocariasis, previous scar, intraocular foreign body, retinopathy of prematurity, or sickle cell retinopathy.

The history and examination should be concentrated on identifying if any of these inciting cofactors exist. The physical examination should include visual acuity, pupillary response (retinal detachment can be associated with afferent pupillary defect), confrontational visual field testing, slit lamp examination looking for pigment cells in the anterior vitreous, intraocular pressure testing, and indirect ophthalmoscopy by an ophthalmologist if a detachment is suspected.

The differential diagnosis of retinal detachment is fairly limited, and includes age-related and degenerative or juvenile retinoschisis and retinal artery or vein occlusion.

No emergency department laboratory testing is warranted unless a comorbid condition is suspected or identified. Preoperative labs may be helpful if operative repair is anticipated. Ultrasound imaging by a trained emergency physician may be a helpful diagnostic tool. (J Emerg Med 2009;37[4]:415; Acad Emerg Med 2002;9[8]:791.) B-scan ultrasonography is commonly used to make a definitive diagnosis, but there is no role for CT or MRI in the diagnosis. The photograph here depicts inferior retinal detachment as seen on indirect ophthalmoscopy.

An ophthalmologist should be consulted emergently if a diagnosis of retinal detachment is suspected. Treatment depends on the severity, type, acuity, and location of the detachment. Patients with a suspected retinal detachment from trauma should have the globe protected with goggles or shield, and measures should be taken to avoid increased globe pressure. Patients with acute retinal detachment that threaten or do not yet involve the fovea or macula require emergent repair. Detachments that involve the macula (“macula-off”) can be repaired electively, typically within a few weeks. The type of treatment depends on the detachment, but can include in-office procedures including pneumatic retinopexy (intraocular gas insertion with concomitant cryo or laser to retinal break) or operative repair including scleral buckle and primary vitrectomy.

This patient was found to have a rhegmatogenous peripheral retinal detachment not involving the macula, which was confirmed on B-scan ultrasound. He was taken to the OR that evening for surgical repair with scleral buckle and vitrectomy.

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Dr. Wileris an assistant professor of emergency medicine and the medical director of reimbursement at the University of Colorado Denver School of Medicine and an adjunct assistant professor of emergency medicine at the Washington University School of Medicine in St. Louis.

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FastLinks

▪ Read all of Dr. Wiler's past columns in the EM-News.com archive.

▪ Comments about this article? Write to EMN at emn@lww.com.

© 2012 Lippincott Williams & Wilkins, Inc.