Central Retinal Artery Occlusion in a 70-Year-Old Man

THE CASE:

A 70-year-old man complains of a sudden, painless loss ofvision in the left eye that occurred several hours earlier. He denies traumaand previous visual disturbances. His history is significant for peripheralvascular disease and type 2 diabetes mellitus.The patient's vital signs are stable. The left pupil is 2 mm larger thanthe right. He has full range of motion in both eyes but markedly decreasedvisual acuity in the left eye. Palpation of the temporal arteries reveals notenderness.What is the most likely cause of this patient's vision loss?

• Acute glaucoma
• Amaurosis fugax
• Central retinal artery occlusion
• Central retinal vein occlusion
• Temporal arteritis

DISCUSSION:

The patient has

central retinal artery occlusion

(CRAO), apainless loss of monocular vision that is considered an ophthalmologic emergency.Retinal embolism is a common cause of CRAO; others include atheroscleroticchanges, angiospasm, and inflammatory endarteritis. CRAO developsin approximately 25% of patients with diabetes and in a significant numberof patients with atherosclerotic disease--especially those between theages of 40 and 60 years. Bilateral involvement occurs in 1% to 2% of patients;men are affected slightly more often than women.Funduscopic examination reveals a pale retina with edema, a cherry redspot at the macula, an afferent pupillary defect, and boxcar segmentation ofthe blood column. In approximately20% of cases, emboli are visible duringfunduscopy.Emergent referral to an ophthalmologistis mandatory. Treatmentinvolves measures to increaseretinal perfusion and oxygenationand lower intraocular pressure(IOP). Vasodilators help increaseretinal perfusion; having the patientbreathe higher pressures of oxygenreduces ischemia to the retinal tissue.Ocular massage, carbonic anhydraseinhibitors, and β-adrenergicblocking agents reduce IOP. Additionaltherapeutic interventions includeanterior chamber paracentesis,antithrombolytics, and hyperbaricoxygen therapy. Once the occlusionis addressed, its cause must beinvestigated. Despite early and aggressive therapy, 20% to 35% of patientslose vision in the affected eye.Patients with

acute glaucoma

often present with blurred vision and eyediscomfort of acute onset. They sometimes report associated nausea andvomiting and halos around lights. Examination may reveal conjunctivalinjection, a hazy cornea, and a pupil that is fixed in mid-position. Funduscopicfindings are often normal, and IOP is elevated.

Amaurosis fugax

manifests with fleeting attacks of monocular visionloss with partial or total blindness that lasts seconds to minutes. Visualacuity is normal and funduscopic examination is unremarkable.Patients with

central retinal vein occlusion

complain of painless visionloss that occurs over several hours. They exhibit a "blood and thunder"fundus (diffuse retinal edema and hemorrhages).Temporal artery discomfort suggests

temporal arteritis.

A normalerythrocyte sedimentation rate rules out this condition.

References:

FOR MORE INFORMATION:

• Knoop K, Trott A. Ophthalmologic procedures in the emergency department, part I: immediate sight-savingprocedures. Acad Emerg Med. 1994;1:408-412.
• Rhee DJ, Pyfer M. Central retinal artery occlusion. In: Rhee DJ, Pyfer MF, eds. The Wills Eye Manual: Officeand Emergency Room Diagnosis and Treatment of Eye Disease. 3rd ed. Philadelphia: Lippincott Williams& Wilkins; 1999:331-335.