76: Acute Visual Loss

Key Points

• History and physical examination alone will 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 pain, suspect central retinal artery occlusion (CRAO), central retinal vein occlusion (CRVO), or retinal detachment.

• 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.

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

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 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 ...