crusting

Conjunctivitis

and subconjunctival hemorrhage can be discharged to follow-up with their primary care physicians.

SUGGESTED READING

Cronau H, et al. Diagnosis and management of red eye in pri ­

mary care. Am Fam Physician. 20 1 0;81:1 37-144.

Jackson WB. Acute Red Eye: Diagnosis and Treatment Guidelines.

Ottawa, Ontario, Canada: University of Ottawa Eye Institute,

2004.

Kerns BL, Mason JD. Red eye: A guide through the differential

diagnosis. Emer Med. 2004;36:3 1-40.

Leibowitz HM. The red eye. N Engl J Med. 2000;343:345-35 1.

Walker RA, Adhikari S. Eye emergencies. In: Tintinalli JE,

Stapczynski JS, Ma OJ, Cline DM, Cydulka RK, Meckler GD.

Tintinalli's Emergency Medicine: A Comprehensive Study Guide.

7th ed. New York, NY: McGraw-Hill, 201 1, pp. 1517-1549.

Acute Visual Loss

jordan B. Moskoff, MD

Key Points

• History and physical examination alone wi ll lead to the

diagnosis in most patients presenting with acute visual loss.

• The most important first step in addressing the patient

with acute monocular visual loss is to determine

whether the loss of vision is associated with pain.

• In patients with acute visual loss without pa in, suspect

centra l retinal artery occlusion (CRAO), central reti nal

vein occlusion (CRVO), or retinal detachment.

INTRODUCTION

Central retinal artery occlusion ( CRAO) and central retinal

vein occlusion ( CRVO) occur most frequently in elderly

patients. About 90% of cases of CRVO occur in patients

older than 50 years. CRAO is a result of a thrombotic plaque

or more commonly an embolus of the central retinal artery,

whereas CRVO is caused by thrombosis of the retinal vein.

Optic neuritis is a painful rapid reduction of central

vision secondary to an inflammatory process of the optic

nerve. Optic neuritis occurs more commonly in women

aged 15 to 45 years. Retinal detachment results from

traction of the vitreous humor on the retina. This causes a

tear in the retina and a separation of the inner neuronal

retina from the outer pigment epithelial layer. Retinal

detachment may occur after ocular trauma, but in

atraumatic cases, this condition is more prevalent in men

>45 years old and in patients with significant myopia. The

prevalence in the United States is 0.3%.

Temporal (giant cell) arteritis is a vasculitis that results

in monocular loss of vision associated with a unilateral

temporal headache. Temporal arteritis occurs most

commonly in woman >50 years old. Whites are more

frequently affected than are other races. Temporal arteritis

319

• Patients with acute visual loss with associated pain may

have optic neu ritis, temporal (giant cel l) arteritis, acute

angle-closure glaucoma, or a large central cornea l abrasion or ulceration.

• An ophtha lmologist should be consulted immediately

when CRAO or acute angle-closure glaucoma are diagnosed in the emergency department.

is a vasculitis of medium and large arteries and can lead to

optic nerve infarction and blindness.

Acute angle-closure glaucoma is a sudden painful

monocular loss of vision secondary to increased pressure

in the anterior chamber. Acute angle-closure glaucoma

represents < 10% of all cases of glaucoma in the United

States. It is more common in women and is also more

common in African American and Asian populations.

Acute angle-closure glaucoma occurs in patients with

shallow (narrow) anterior chamber angles. As the pupil

dilates, the iris leaflet touches the lens. This impedes the

flow of aqueous humor from the posterior to the anterior

chamber with a subsequent increase in hydrostatic pressure.

CLINICAL PRESENTATION

..... History

Painless, acute loss of vision is characteristic of CRAO,

CRVO, and retinal detachment. In patients with CRAO, the

monocular vision loss is usually complete and quite

sudden. Risk factors include hypertension, carotid artery

disease, diabetes mellitus, cardiac disease (especially atrial

fibrillation and valvular disease), vasculitis, temporal

CHAPTER 76

artentls, and sickle cell disease. Central retinal artery

occlusion must be considered and treated early because

irreversible visual loss occurs after 90 minutes.

The presentation of CRVO is more insidious than retinal

artery occlusion. The patient will have a sudden painless

monocular decrease in vision that is most commonly noted

on awakening. Patients may also describe a sudden decrease,

acutely imposed on a chronic gradual worsening over a

longer period of time ( eg, 1 week). Risk relates to likelihood

of thrombosis. The physician should have increased suspicion in patients with diabetes mellitus, hypertension, arteriosclerosis, chronic glaucoma, and vasculitis.

Patients with retinal detachment present with painless

loss of vision often described as a sensation of a curtain

moving across the visual field or a shade being pulled

down over the eye. Flashing lights, "spider webs," or "coal

dust" in the visual field may precede visual loss. Risk is

related most closely to severe myopia. Other risk factors

include trauma, previous cataract surgery, family history,

Marfan syndrome (or other inherited connective tissue

disorders), and diabetes mellitus.

Painful loss of vision is seen in patients with optic

neuritis, temporal arteritis, and acute angle closure

glaucoma. Patients with optic neuritis will present with r apidly progressive reduction or blurring of their vision. Ocular

pain worsens with eye movement In patients without a

previous diagnosis, 25-65% will develop multiple sclerosis.

Temporal arteritis presents as a sudden monocular loss of

vision associated with a unilateral temporal headache. Eye

pain usually is not present. Risk factors include polymyalgia

rheumatica, female, Northern European descent, and

>50 years old.

Lastly, acute angle-closure glaucoma presents as cloudy

vision associated with halos around lights. In addition, the

patient will complain of eye pain or headache along with

nausea and vomiting and possibly abdominal pain. Often

patients will have no previous history of glaucoma.

Farsighted (hyperopic) persons are at r isk secondary to the

shape of their anterior chamber; female and elderly

patients are also at increased risk.

..... Physical Examination

For a full description of the physical examination of the

eye, see Chapter 75. In acute visual loss, fluorescein staining is essential to exclude corneal abrasions or ulcerations;

however, the funduscopic examination is usually most

diagnostic. To perform the funduscopic exam, allow the

patient to sit in a dark room for several minutes before

starting. When the pupil is sufficiently dilated, ask the

patient to focus on an object on the wall and ignore the

examiner. Focus the ophthalmoscope on the eye and

gradually approach the cornea from a lateral position. The

optic disc is noted medially. If only vessels are seen, the

optic disc can be located by knowing that the blood vessel's

branches "point" to the direction of the disc.

A

8

Figure 76-1 . A. Central retinal artery occlusion.

B. Central retinal vein occlusion.

CRAO

Visual acuity is markedly decreased, with the patient often

only able to perceive shadows or count fingers. Initial pupil

examination may be normal; however, after 1-2 hours, the

pupil may dilate. The pupil is poorly reactive to direct light

but has a greater consensual response to light (afferent

pupillary defect). On funduscopic examination, a pale

retina with a cherry-red spotin the macular area (fovea) is

the classic finding (Figure 76-1A).

CRVO

Visual acuity is variable but the deficit is usually less

severe than retinal artery occlusion. The patient may

retain the ability to see shadows or count fingers. The

pupil will react sluggishly to light. On funduscopic examination, there may be retinal hemorrhage, tortuous retinal

veins, and disc edema, referred to as "blood and thunder"

(Figure 76-1B).

ACUTE VISUAL LOSS

.6. Figure 76-2. Retinal detachment on bedside

u ltrasound.

Retinal detachment

The extent of the loss of vision is dependent on the degree

of detachment. Visual field defects will be noted on con ­

frontation. The pupil examination is unremarkable.

Funduscopic examination reveals an undulating, dull grey,

detached retina. Ocular ultrasound is a bedside procedure

that is very helpful to making the diagnosis of retinal

detachment (Figure 76-2).

Optic neuritis

Visual acuity varies from mildly reduced to no light

perception. Often the visual deficit will be limited to the

central visual field, and the patient will c omplain more of a

defect with color vision rather than sight. This can be evaluated using the red desaturation test.Have the patient look at

a dark red object with one eye and then test the other eye to

see if the object looks the same color. The affected eye will

often see the object as lighter or pink. An afferent pupillary

defect will often be present. If the fundus is normal, the

patient has retrobulbar optic neuritis. However, if the fundus is swollen or hyperemic, the patient has papillitis.

Temporal arteritis

Palpation may reveal tender, tortuous, and sometimes

pulseless temporal arteries. The degree of loss of vision

depends on when the diagnosis is made. If diagnosed late,

visual acuity will be markedly decreased. An afferent pupillary defect may be present. On funduscopic examination, a

pale, swollen optic disc will be present.

A

8

.6. Figure 76-3. A. Schititz tonometer B. Tono-Pen.

Acute angle-closure glaucoma

Visual acuity is markedly decreased. The patient's sclera

will be red due to ciliary injection. The cornea will be

cloudy. On gentle palpation, the eye may have a rock hard

consistency. The pupil is mid-dilated and nonreactive to

light. Funduscopic examination is difficult to perform in

the face of a cloudy cornea, but is otherwise unremarkable.

To diagnose acute angle-closure glaucoma, intraocular

pressure is measured with a Schiotz tonometer or TonoPen (Figure 76-3). Normal pressure is <20 mmHg. A pressure >40 mmHg is diagnostic.

DIAGNOSTIC FINDINGS

When temporal arteritis is suspected, an erythrocyte

sedimentation rate (ESR) should be obtained. An ESR

Retinal

detachment

CHAPTER 76

Increased

lOP

Glaucoma

Normal

lOP

Optic

neuritis

Headache

with

pain less

eye and

elevated

ESR

Temporal

arteritis

.A Figure 76-4. Acute visua l loss diagnostic algorithm. ESR, erythrocyte sedimentation rate;

lOP, intraocu lar pressure.

>50 mm/hr is almost universally present in patients with

temporal arteritis. Normal ESR for males is age/2; females

(age + 1 0)/2.