Blurred Vision

Gary K. Phelps

Blurred vision is a common, very nonspecific presenting ophthalmic complaint. Normal visual function requires a sharp image created by the lenses (cornea and crystalline lens) of the eye onto the retina, accurate translation from light to electrical energy by the retina, and transmission of that information through the optic nerve to the chiasm (where the information from each eye is mixed), through the lateral geniculate to the occipital cortex where the image is interpreted and compared with associated information in memory. Failure of any part of the system can be interpreted as blurred vision. Problems anterior to the chiasm cause monocular disturbances, posterior to the chiasm binocular. The critical aspect is to identify the small number of patients requiring immediate intervention to alter the disease course (1).

Approach

The causes of blurred vision are myriad, but are best considered in three anatomic areas.

Optical problems include refractive errors, cataract, corneal opacity, and uveitis. Receptor (retinal) problems include macular degeneration, diabetic macular edema, and retinal vascular occlusions. Neurologic pathway problems encompass such entities as optic neuritis and occipital stroke.

History

A. Timing of blurred vision. Most causes of blurred vision requiring acute intervention are of sudden, recent onset, with the exception of tumor compression, which can be gradual. Episodes of transient duration tend to be more benign, whereas those that are worsening or long term in nature tend to be more ominous.

B. Nature of blurred vision. The monocular, binocular, central, hemianopic, peripheral, color saturation, distortion, or negative nature (loss of area of vision) or positive nature (seeing things that are not there) provides clues to the location and nature of the disease. Binocularity, loss of color saturation, and hemianopic visual loss suggest neurologic disease, whereas monocular, central, and distortion suggest retinal disease.

C. Associated symptoms. Other symptoms, acute or remote in time or location (e.g., hemiparesis, dysarthria, or diplopia) point to neurologic disease (multiple sclerosis, transient ischemic attacks, acute or recurrent stroke, and so on) of which visual blurring is simply one part (Chapter 4.8). Giant cell arteritis, stroke, embolic disease, retinal detachment, and macular degeneration are far more common in the aging population. Diabetes mellitus has a high risk of associated retinal vascular disease, especially in the second decade of duration (Chapter 14.1). Trauma-induced visual blurring is usually self-evident by history or physical examination.

Physical examination

 A. Gross examination. Visual acuity (VA) can be measured at distance or near; it should be done in each eye independently and is best done with spectacles or contact lenses in place. Gross inspecting for visualization of clear iris detail quickly evaluates for corneal clouding or hyphema. Confrontation visual fields (VF) are done by comparing the patient’s ability to count fingers in all four quadrants to the examiner. A relative afferent pupillary defect, where light shined into one eye causes both pupils to become smaller than light shined into the other, screens for conduction defects of the optic nerve.

 B. Instrument-assisted examination. A clear red reflex with a direct ophthalmoscope eliminates opacities of the cornea or lens and the funduscopic examination identifies a normal macular reflex and a healthy optic nerve. Acute glaucoma is easily screened with a tonometer (Schiotz or Goldman applanation with a slit lamp biomicroscope): a pressure of greater than 30 mm Hg is highly suspicious.

Testing

A. Laboratory. Erythrocyte sedimentation rate (ESR) and C-reactive protein are pertinent laboratory screens for giant cell arteritis.

B. Diagnostic imaging. Computed tomography (CT) or magnetic resonance imaging (MRI) scans are useful primarily in cases of trauma to identify disruption of the orbit or orbital hemorrhages or masses, stroke syndromes, or compressive lesions of the optic nerve, chiasm pathways to the occipital lobe, or occipital lobe.

Diagnostic assessment

(Table 5.1). Transient blurring that clears with blinking is usually tear film-related and can be investigated at leisure. Gradual visual loss, which improves greatly with a pinhole, is almost always optical and can await delayed evaluation. Blurred vision at near can be secondary to aging (presbyopia) or orally or topically administered parasympathomimetic drugs. Sudden monocular loss associated with a relative afferent pupillary defect demands immediate assessment for giant cell arteritis or optic neuritis (vascular or demyelinating). Sudden onset of hemianopic bilateral VF defects, particularly if associated with pain or other neurologic defects, demands immediate evaluation for stroke syndrome (vascular or compressive secondary to tumor). Blurred vision associated with trauma such as corneal foreign body, hyphema, or ruptured globe is usually self-evident. Repeated transient obscurations of minutes in nature, particularly in young and frequently overweight female patients, may indicate optic nerve compression and careful funduscopic examination is necessary to rule out papilledema with increased intracranial pressure (e.g., essential intracranial hypertension). Transient, positive visual disturbances are usually benign (e.g., recurrent migraine scotoma—“scintillating scotoma”—or retinal regenerative phenomena—“after images”). A single episode without ancillary migraine history should arouse suspicion of early stroke syndrome or retinal tear and requires ophthalmic or neurologic workup. Intermittent or persistent episodes of blurred vision, especially combined with a history of pain (sometimes referred to the chest or abdomen), photophobia, halos, red eye, and a duration longer than a few minutes, are diagnostic clues of pupillary block glaucoma or uveitis.

References

1. Glaser JS, Goodwin JA. The visual sensory system. In: Tasman W, Jaeger EA, eds. Duane’s clinical ophthalmology, Vol 2. Philadelphia: Lippincott, Williams & Wilkins, 1998:(2):1–26.

Book Source Details

• Book Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter
• Author(s): Robert B. Taylor (editor)
• Year of Publication: 2000
• Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.

Other Book Chapters Related to Blurred vision

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Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2008 Williams & Wilkins.

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• Back to symptom: Blurred vision: Introduction (review 811 causes)
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More About This Book: Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter Authors: Robert B. Taylor (editor) Publisher: Lippincott Williams & Wilkins Copyright: 2000 ISBN: 0-78172-094-X

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