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  History and physical examination alone will lead to the diagnosis in most patients presenting with acute visual loss.

  
  
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  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.

  
  
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  In patients with acute visual loss without pain, suspect central retinal artery occlusion (CRAO), central retinal vein occlusion (CRVO), or retinal detachment.

  
  
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  Patients with acute visual loss with associated pain may have optic neuritis, temporal (giant cell) arteritis, acute angle-closure glaucoma, or a large central corneal abrasion or ulceration.

  
  
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  An ophthalmologist should be consulted immediately when CRAO or acute angle-closure glaucoma are diagnosed in the emergency department.

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 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.

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 arteritis, 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 rapidly 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 risk 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.