CLINICAL

  POSTERIOR

STABILIZE VISION

DON’T LET THIS OCULAR EMERGENCY ROB YOUR PATIENTS’ VISION AND HEALTH

SHERROL A. REYNOLDS, O.D., F.A.A.O.

A 70-YEAR-OLD black female presented complaining of sudden severe loss of vision OD for one day. She denied symptoms of pain, scalp tenderness, malaise or jaw claudication. Her medical history was significant for coronary heart disease with prior coronary bypass surgery, carotid artery disease, hypertension, diabetes and hypercholesterolemia. In addition to taking medications for the aforementioned conditions, the patient also used baby aspirin (81 mg of Ecotrin) and clopidogrel (Plavix, Bristol-Myers Squibb) to prevent heart attacks and strokes.

The patient’s BCVA was 20/counting fingers OD with no improvement on pinhole testing and 20/20 OS. Examination revealed a relative afferent pupillary defect OD. Ocular motilities were unremarkable. Confrontation visual field showed a significant field defect OD and was normal OS. In-office blood pressure was 140/90 mm Hg. IOPs were 18 mmHg OD and OS. Dilated examination revealed a well-centered posterior chamber IOL post-YAG laser capsulotomy OU. Retinal evaluation showed a “whitened” edematous retina with opacification and a cherry-red spot OD. Arteriovenous crossing changes, indicative of hypertensive retinopathy, were observed OS, and the peripheral retina was clear OU.

Were the patient’s symptoms and clinical findings indicative of central retinal vein occlusion or central retinal artery occlusion (CRAO)?

Here, I discuss the etiology, symptoms, clinical signs and diagnosis/management of CRAO to help you determine the diagnosis of this patient.

ETIOLOGY

CRAO primarily affects patients older than age 60, with males slightly more affected. The condition is uncommon in patients younger than age 30, but when it does occur in this age group, coagulopathies (homocystinuria, factor V Leiden and anti-thrombin deficiencies), congenital heart disorders (mitral valve prolapse), migraines or oral contraceptive use must be considered as causes of embolic obstruction, which induces CRAO.

CRAO is predominantly caused by carotid artery emboli, but other factors include thrombotic, vasospastic and vasculitic events. Emboli composed of cholesterol (also know as Hollenhorst plaque) occur in 75% of cases, while calcific and fibrinous emboli, indicative of cardiac abnormalities, occur in 10% to 15% of CRAO patients, according to “Ophthalmology.”

Other risk factors for CRAO include hypertension, dyslipidemia, diabetes, cardiac lesions (bacterial endocarditis), inflammation (giant cell arteritis), past cigarette smoking, thrombophilic disorders (antiphospholipid syndrome, protein S/C deficiencies, sickle cell disease, leukemia or lymphoma), medications (oral contraceptives, sildenafil [Viagra, Pfizer] and hormone medications.) Exogenous emboli can result from tumors, parasitic or fungal infections, congenital conditions (Susac syndrome), talc emboli from intravenous drug use and trauma. Raised IOP, optic nerve head drusen or ocular surgeries may pose a risk as well.

SYMPTOMS

Performing a thorough history is essential in identifying the symptoms associated with a risk of CRAO. These symptoms:

• Previous episodes of transient visual loss, such as amaurosis fugax (AF) (According to “Retina,” AF occurred in up to 10% of CRAO patients.)

• Transient ischemic attacks and cerebrovascular accidents (strokes)

CLINICAL SIGNS

• Acute profound painless unilateral vision loss (20/400 counting fingers or worse. Sparing of the cilioretinal artery, a branch of the posterior ciliary artery, which occurs in about 25% of CRAO cases results in visual acuity of 20/50 or better.)

• Positive afferent pupillary defect

• Significant visual field defect

• Cherry-red spot (presence of choroidal circulation)

• Pale or “whitened” edematous retina

• Narrowed retinal artery

• Segmental arterial blood flow (“boxcarring” or “cattle-trucking”)

• Retinal emboli (lodged at artery bifurcations and detectable in up to 23% of CRAO patients, according to “Retina.”)

Chronic complications include:

• Optic atrophy

• Arteriolar sheathing

• Collateral vessels (Although rare, arteriolar collaterals can occur.)

• Macular retinal pigmentary changes

• Neovascularization (This is rare. If noted, other causes, such as diabetic retinopathy should be considered.)

DIAGNOSIS/MANAGEMENT

CRAO requires intervention within 90 minutes of onset to improve visual chances, but even then, the prognosis is rather poor. To make a definitive diagnosis, it is important to inquire about the aforementioned risks factors and symptoms, perform in-office blood pressure and a pulse evaluation, auscultate the patient’s carotid artery and assess the fellow eye. As CRAO is bilateral in about 1% to 2% of patients and may provide clues to possible underlying pathology, according to “Retina,” acquire retinal photos, visual field testing and/or OCT for detail on structural changes, including characterizing the artery emboli.

Although there is not a single proven modality of treatment, ocular massage to dislodge the emboli, reducing IOP, paracentesis and intravenous tissue-type plasminogen activator have been used. There are anecdotal reports of success with hyperbaric oxygen therapy.

Note the “whitened” edematous retina and cherry-red spot.
Courtesy: Dr. Diana Shechtman

CRAO requires close monitoring and co-management with the treating physician. Specifically, refer the patient for carotid artery Doppler and ultrasound evaluations in addition to diabetes, lipid, clotting disorder, cardiac evaluation, imaging studies and ESR and CRP assessments (the latter two are necessary in patients older than 50, as about 10% of CRAO cases are associated with giant cell arteritis, according to the “American Journal of Ophthalmology”). Patients with retinal artery emboli have a 56% mortality rate, and those with a CRAO have a life expectancy of 5.5 years compared with 15.4 years for those without CRAO, according to the “Journal of Neuro-Ophthalmology.”

THE ANSWER

If you diagnosed this patient with central retinal vein occlusion you are incorrect! The aforementioned patient’s classical symptoms and signs, along with her extensive medical conditions, particularly carotid artery disease, revealed CRAO. Given that she presented one day after onset, ocular digital massage was not attempted. She was immediately referred to her primary care physician and cardiologist for further testing. Carotid artery testing revealed significant disease on the same side as the CRAO that required endarterectomy surgery. Co-management with the retinal specialist revealed delayed vessel filling on fluorescein angiography. Her vision remained counting fingers OD at one-week follow-up and one-month follow-up. She is being closely monitored with three-month follow-up care.

CRAO necessitates urgent medical management to stabilize vision, determine and treat the underlying systemic cause and prevent complications. Optometrists play a vital role with timely diagnosis, which can potentially save a life, prevent future life-threatening events and preserve vision in the unaffected eye. OM

DR. REYNOLDS is an associate professor at the Nova Southeastern University College of Optometry and clinical preceptor/attending in the college’s diabetes and macular clinic. She is a fellow of the Optometric Retina Society and chairperson for the Florida Optometric Association Healthy Eyes Healthy People Committee. Comment at tinyurl.com/OMcomment.