Visual blurring

Visual blurring is a common symptom that refers to the loss of visual acuity with indistinct visual details. It may result from eye injury, a neurologic or eye disorder, or a disorder with vascular complications, such as diabetes mellitus. Visual blurring may also result from mucus passing over the cornea, a refractive error, improperly fitted contact lenses, or certain drugs.

History and physical examination

If your patient has visual blurring accompanied by sudden, severe eye pain, a history of trauma, or sudden vision loss, order an ophthalmologic examination. (See Managing sudden vision loss, page 629.) If the patient has a penetrating or perforating eye injury, don’t touch the eye.

If the patient isn’t in distress, ask him how long he has had the visual blurring. Does it occur only at certain times? Ask about associated signs and symptoms, such as pain or discharge. If visual blurring followed injury, obtain details of the accident, and ask if vision was impaired immediately after the injury. Obtain a medical and drug history.

Inspect the patient’s eye, noting lid edema, drainage, or conjunctival or scleral redness. Also note an irregularly shaped iris, which may indicate previous trauma, and excessive blinking, which may indicate corneal damage. Assess the patient for pupillary changes, and test visual acuity in both eyes. (See Testing visual acuity, page 630.)

Medical causes

Brain tumor

Visual blurring may occur with a brain tumor. Associated findings include decreased level of consciousness (LOC), headache, apathy, behavioral changes, memory loss, decreased attention span, dizziness, and confusion. A tumor can also cause aphasia, seizures, ataxia, and signs of hormonal imbalance. Its later effects are papilledema, vomiting, increased systolic blood pressure, widened pulse pressure, and decorticate posture.

Cataract

Cataract is a painless disorder that causes gradual visual blurring. Other effects include halo vision (an early sign), visual glare in bright light, progressive vision loss, and a gray pupil that later turns milky white.

Concussion

Immediately or shortly after blunt head trauma, vision may be blurred, double, or temporarily lost. Other findings include changes in LOC and behavior.

Corneal abrasions

Visual blurring may occur with severe eye pain, photophobia, redness, and excessive tearing.

Corneal foreign bodies

Visual blurring may accompany a foreign-body sensation, excessive tearing, photophobia, intense eye pain, miosis, conjunctival injection, and a dark corneal speck.

Diabetic retinopathy

Retinal edema and hemorrhage produce gradual blurring, which may progress to blindness.

Dislocated lens

Dislocation of the lens, especially beyond the line of vision, causes visual blurring and (with trauma) redness.

Eye tumor

If the tumor involves the macula, visual blurring may be the presenting symptom. Related findings include varying visual field losses.

Glaucoma

With acute angle-closure glaucoma, an ocular emergency, unilateral visual blurring and severe pain begin suddenly. Other findings include halo vision; a moderately dilated, nonreactive pupil; conjunctival injection; a cloudy cornea; and decreased visual acuity. Severely elevated intraocular pressure may cause nausea and vomiting.

With chronic angle-closure glaucoma, transient visual blurring and halo vision may precede pain and blindness.

Hereditary corneal dystrophies

Visual blurring may remain stable or may progressively worsen throughout life. Some dystrophies cause associated pain, vision loss, photophobia, tearing, and corneal opacities.

Hypertension

Hypertension may cause visual blurring and a constant morning headache that decreases in severity during the day. If diastolic blood pressure exceeds 120 mm Hg, the patient may report a severe, throbbing headache. Associated findings include restlessness, confusion, nausea, vomiting, seizures, and decreased LOC.

Hyphema

Blunt eye trauma with hemorrhage into the anterior chamber causes visual blurring. Other effects include moderate pain, diffuse conjunctival injection, visible blood in the anterior chamber, ecchymoses, eyelid edema, and a hard eye.

Iritis

Acute iritis causes sudden visual blurring, moderate to severe eye pain, photophobia, conjunctival injection, and a constricted pupil.

Optic neuritis

Inflammation, degeneration, or demyelinization of the optic nerve usually causes an acute attack of visual blurring and vision loss. Related findings include scotomas and eye pain. Ophthalmoscopic examination reveals hyperemia of the optic disk, large vein distention, blurred disk margins, and filling of the physiologic cup.

Retinal detachment

Sudden visual blurring may be the initial symptom of retinal detachment. Blurring worsens, accompanied by visual floaters and recurring flashes of light. Progressive detachment increases vision loss.

Retinal vein occlusion (central)

Retinal vein occlusion causes gradual unilateral visual blurring and varying degrees of vision loss.

Senile macular degeneration

Senile macular degeneration may cause visual blurring (initially worse at night) and slowly or rapidly progressive vision loss.

Stroke

Brief attacks of bilateral visual blurring may precede or accompany a stroke. Associated findings include a decreased LOC, contralateral hemiplegia, dysarthria, dysphagia, ataxia, unilateral sensory loss, and apraxia. Stroke may also cause agnosia, aphasia, homonymous hemianopia, diplopia, disorientation, memory loss, and poor judgment. Other features include urine retention or urinary incontinence, constipation, personality changes, emotional lability, headache, vomiting, and seizures.

Temporal arteritis

Most common in women older than age 60, this disorder causes sudden blurred vision accompanied by vision loss and a throbbing unilateral headache in the temporal or frontotemporal region. Prodromal signs and symptoms include malaise, anorexia, weight loss, weakness, low-grade fever, and generalized muscle aches. Other findings include confusion; disorientation; swollen, nodular, tender temporal arteries; and erythema of overlying skin.

Vitreous hemorrhage

Sudden unilateral visual blurring and varying vision loss occur with this condition. Visual floaters or dark streaks may also occur.

Other causes

Drugs

Visual blurring may stem from the effects of cycloplegics, guanethidine, reserpine, clomiphene, phenylbutazone, thiazide diuretics, antihistamines, anticholinergics, or phenothiazines.

Special considerations

Prepare the patient for diagnostic tests, such as tonometry, slit-lamp examination, X-rays of the skull and orbit and, if a neurologic lesion is suspected, a computed tomography scan. As necessary, teach him how to instill ophthalmic medication. If visual blurring leads to permanent vision loss, provide emotional support, orient him to his surroundings, and provide for his safety. If necessary, prepare him for surgery.

Pediatric pointers

Visual blurring in children may stem from congenital syphilis, congenital cataracts, refractive errors, eye injuries or infections, and increased intracranial pressure. Refer the child to an ophthalmologist if appropriate.

Test vision in school-age children as you would in adults; test children ages 3 to 6 with the Snellen symbol chart. (See Testing visual acuity, page 630.) Test toddlers with Allen cards, each illustrated with a familiar object, such as an animal. Ask the child to cover one eye and identify the objects as you flash them. Then, ask him to identify them as you gradually back away. Record the maximum distance at which he can identify at least three pictures.

Book Source Details

• Book Title: Handbook of Signs & Symptoms (Third Edition)
• Author(s): Springhouse
• Year of Publication: 2006
• Copyright Details: Handbook of Signs & Symptoms (Third Edition), Copyright © 2006 Lippincott Williams & Wilkins.

Other Book Chapters Related to Vision loss

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Copyright Details: Handbook of Signs & Symptoms (Third Edition), Copyright © 2008 Williams & Wilkins.

More About Causes of Vision loss

• Back to symptom: Vision loss: Introduction (review 645 causes)
• Next Book Extract About Vision loss: Visual floaters (Handbook of Signs & Symptoms (Third Edition))
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More About This Book: Title: Handbook of Signs & Symptoms (Third Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2006 ISBN: 1-58255-402-1

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