Loss of vision is usually considered acute if it develops within a few minutes to a couple of days. It may affect one or both eyes and all or part of a visual field. Patients with small visual field defects (eg, caused by a small retinal detachment) may describe their symptoms as blurred vision.
Pathophysiology of Acute Vision Loss
Acute loss of vision has 3 general causes:
Opacification of normally transparent structures through which light rays pass to reach the retina (eg, cornea, vitreous)
Retinal abnormalities
Abnormalities affecting the optic nerve or visual pathways
Etiology of Acute Vision Loss
The most common causes of acute loss of vision are
Vascular occlusions of the retina (central retinal artery occlusion, central retinal vein occlusion)
Ischemic optic neuropathy (often in patients with temporal arteritis)
Vitreous hemorrhage (caused by diabetic retinopathy or trauma)
In addition, sudden recognition of loss of vision (pseudo-sudden loss of vision) may manifest initially as sudden onset. For example, a patient with long-standing reduced vision in one eye (possibly caused by a dense cataract) suddenly is aware of the reduced vision in the affected eye when covering the unaffected eye.
Presence or absence of pain helps categorize loss of vision (see table Some Causes of Acute Vision Loss).
Most disorders that cause total loss of vision when they affect the entire eye may affect only part of the eye and cause only a visual field defect (eg, branch occlusion of the retinal artery or retinal vein, local retinal detachment).
Less common causes of acute loss of vision include
Anterior uveitis (a common disorder, but one that usually causes eye pain severe enough to trigger evaluation before vision is lost)
Aggressive retinitis
Evaluation of Acute Vision Loss
History
History of present illness should describe loss of vision in terms of onset, duration, progression, and location (whether it is monocular or binocular and whether it involves the entire visual field or a specific part and which part). Important associated visual symptoms include floaters, flashing lights, halos around lights, distorted color vision, and jagged or mosaic patterns (scintillating scotomata). The patient should be asked about eye pain and whether it is constant or occurs only with eye movement.
Review of systems should seek extraocular symptoms of possible causes, including jaw or tongue claudication, temporal headache, proximal muscle pain, and stiffness (giant cell arteritis); and headaches (ocular migraine).
Past medical history should seek known risk factors for eye disorders (eg, contact lens use, severe myopia, recent eye surgery, injection, or injury), risk factors for vascular disease (eg, diabetes, hypertension), and hematologic disorders (eg, sickle cell anemia or disorders such as Waldenström macroglobulinemia or multiple myeloma that could cause a hyperviscosity syndrome).
Family history should note history of migraine headaches.
Physical examination
Vital signs, including temperature, are measured.
If the diagnosis of a transient ischemic attack or stroke (ie, central retinal artery occlusion) presenting as amaurosis fugax is under consideration, a complete neurologic examination is done. The temples are palpated for pulses, tenderness, or nodularity over the course of the temporal artery. However, most of the examination focuses on the eye.
Eye examination includes the following:
Visual acuity is measured.
Peripheral visual fields are assessed by confrontation.
Central visual fields are assessed by Amsler grid.
Direct and consensual pupillary light reflexes are examined using the swinging flashlight test.
Ocular motility is assessed.
Color vision is tested with color plates.
The eyelids, sclera, and conjunctiva are examined using a slit lamp if possible.
The anterior chamber is examined for cells and flare in patients who have eye pain or conjunctival injection.
The lens is checked for cataracts using a direct ophthalmoscope, slit lamp, or both.
Intraocular pressure is measured.
If pupillary light responses are normal and functional loss of vision is suspected (rarely), optokinetic nystagmus is checked. If an optokinetic drum is unavailable, a mirror can be held near the patient’s eye and slowly moved. If the patient can see, the eyes usually track movement of the mirror (considered to be the presence of optokinetic nystagmus).
Red flags
Acute loss of vision is itself a red flag; most causes are serious.
Interpretation of findings
Diagnosis of acute vision loss can be begun systematically. Specific patterns of visual field deficit help suggest a cause. Other clinical findings also help suggest a cause for acute vision loss:
Difficulty seeing the red reflex during ophthalmoscopy suggests opacification of transparent structures (eg, caused by corneal ulcer, vitreous hemorrhage, or severe endophthalmitis).
Retinal abnormalities that are severe enough to cause acute loss of vision are detectable during ophthalmoscopy, particularly if the pupils are dilated. Retinal detachment may appear as a pale billowing parachute; retinal vein occlusion may show marked retinal hemorrhages; and retinal artery occlusion may show pale retina with a cherry-red fovea.
An afferent pupillary defect (absence of a direct pupillary light response but a normal consensual response) with an otherwise normal examination (except sometimes an abnormal optic disk) suggests an abnormality of the optic nerve or retina (ie, anterior to the optic chiasm).
In addition, the following facts may help:
Monocular symptoms suggest a lesion anterior to the optic chiasm.
Bilateral, symmetric (homonymous) visual field defects suggest a lesion posterior to the chiasm.
Constant eye pain suggests a corneal lesion (ulcer or abrasion), anterior chamber inflammation, or increased intraocular pressure, whereas eye pain with movement suggests optic neuritis.
Temporal headaches suggest giant cell arteritis or migraine.
Testing
Erythrocyte sedimentation rate (ESR), C-reactive protein, and platelet count are done for all patients with symptoms (eg, temporal headaches, jaw claudication, proximal myalgias, stiffness) or signs (eg, temporal artery tenderness or induration, pale retina, papilledema) suggesting optic nerve or retinal ischemia to exclude giant cell arteritis.
Other testing is listed in the table Some Causes of Acute Vision Loss. The following are of particular importance:
Ultrasonography is done to view the retina if the retina is not clearly visible with pupillary dilation and indirect ophthalmoscopy done by an ophthalmologist.
Gadolinium-enhanced MRI of the brain and orbits is done for patients who have eye pain with movement or afferent pupillary defect, particularly with optic nerve swelling on ophthalmoscopy, to diagnose multiple sclerosis.
Treatment of Acute Vision Loss
Causative disorders are treated. Treatment should usually commence immediately if the cause is treatable. In many cases (eg, artery occlusions), treatment is unlikely to salvage the affected eye but can decrease the risk of the same process occurring in the contralateral eye or of a complication caused by the same process (eg, ischemic stroke).
Key Points
Diagnosis and treatment should occur as rapidly as possible.
Immediate referral to a stroke center if an acute embolic event is suspected (eg, amaurosis fugax, retinal artery occlusion, ischemic stroke).
Acute monocular loss of vision with an afferent pupillary defect indicates a lesion of the eye or of the optic nerve anterior to the optic chiasm.
Optic nerve lesion, particularly ischemia, is considered in patients with acute monocular loss of vision or afferent pupillary defect without eye pain and in those with or without optic nerve abnormalities on ophthalmoscopy but no other abnormalities on eye examination.
Corneal ulcer, acute angle-closure glaucoma, endophthalmitis, or severe anterior uveitis is considered in patients with acute monocular loss of vision, eye pain, and conjunctival injection.
