Emergency Medicine · Year 3 · from Emergency Medicine

Case 1: Central Retinal Artery Occlusion - Sudden Painless Vision Loss

Patient Demographics

• Age: 68 years
• Sex: Male
• Occupation: Retired banker

Chief Complaint

"I woke up and can't see out of my right eye."

History of Present Illness

A 68-year-old male presents with sudden, painless, complete vision loss in his right eye noticed upon waking 2 hours ago. He initially thought his eye "needed to adjust" but vision has not improved. He denies eye pain, trauma, or headache. He has a history of atrial fibrillation and hypertension but admits he ran out of his warfarin 2 weeks ago.

Initial Assessment

ESI Level: 2 - Time-sensitive vision-threatening emergency

First Impression:

• Appearance: Anxious, well-appearing otherwise
• Work of breathing: Normal
• Circulation: Normal

Vital Signs:

• Heart rate: 82 bpm, irregularly irregular
• Blood pressure: 162/94 mmHg
• Respiratory rate: 14 breaths/min
• SpO2: 98% on room air
• Temperature: 37.0C
• GCS: 15

Primary Survey

Airway: Patent Breathing: Normal Circulation: Irregular pulse (atrial fibrillation), well-perfused Disability: Alert, GCS 15 Exposure: No abnormalities

Time-Critical Concept

Central Retinal Artery Occlusion (CRAO) = "Stroke of the Eye"

• Retinal tolerance for ischemia: 90-100 minutes
• Treatment window: Best within 4-6 hours
• This patient: 2 hours from symptom onset - within treatment window!

Ocular Examination

Visual Acuity:

• Right eye (OD): Hand motion only (severely decreased)
• Left eye (OS): 20/25 (normal for age)

Pupillary Exam:

• Right eye: Afferent pupillary defect (APD) present (Marcus Gunn pupil)
• Direct response: Sluggish
• Consensual response: Normal
• Left eye: Normal responses

Extraocular Movements: Full bilaterally

Visual Fields: Unable to assess OD; full OS

External Exam:

• No proptosis
• No injection
• No discharge

Intraocular Pressure: OD 14 mmHg, OS 16 mmHg (normal)

Fundoscopic Examination:

• Right eye:
• Pale/opaque retina (ischemic edema)
• Cherry-red spot at macula (normal choroidal flush visible through thin macula)
• Attenuated arterioles ("boxcarring" of blood column)
• No visible embolus
• Left eye: Normal

Differential Diagnosis of Sudden Painless Vision Loss

Secondary Survey

SAMPLE History:

• Symptoms: Sudden painless vision loss right eye
• Allergies: None
• Medications: Warfarin (stopped 2 weeks ago), metoprolol, lisinopril
• PMH: Atrial fibrillation, hypertension, hyperlipidemia
• Last Meal: Breakfast this morning
• Events: Noticed on waking, no improvement

Cardiovascular Risk Assessment:

• Atrial fibrillation (off anticoagulation!) - embolic risk
• Hypertension
• Age >50

Management

Immediate Interventions (within treatment window):

1. Ocular massage:

• Apply firm pressure to globe through closed lid for 10-15 seconds
• Release for 10-15 seconds
• Repeat x5-10
• Goal: Dislodge embolus, increase perfusion pressure

1. Lower intraocular pressure:

• Acetazolamide 500mg IV
• Timolol 0.5% one drop
• Goal: Improve perfusion gradient

1. Increase oxygenation:

• High-flow oxygen (may increase retinal O2 delivery)
• Consider hyperbaric oxygen if available

1. Emergent ophthalmology consultation

Ophthalmology Response:

• Anterior chamber paracentesis performed (removes aqueous to rapidly lower IOP)
• Thrombolytic therapy considered (selective intra-arterial tPA - investigational)

Diagnostic Testing

Labs:

• CBC: Normal
• BMP: Normal
• ESR: 28 mm/hr (mildly elevated)
• CRP: 1.2 mg/dL
• Glucose: 118 mg/dL
• Lipid panel: LDL 142 mg/dL
• INR: 1.1 (subtherapeutic - explains embolic event)

ECG: Atrial fibrillation with controlled rate

Additional Workup:

• Carotid ultrasound: 60% stenosis right ICA
• Echocardiogram: No intracardiac thrombus, LA enlargement

Giant Cell Arteritis Consideration:

• Age >50: Yes
• ESR elevated: Mildly
• Headache/jaw claudication/scalp tenderness: None
• Decision: GCA less likely, but ESR monitored

Diagnosis

Central Retinal Artery Occlusion (CRAO) - likely cardioembolic secondary to atrial fibrillation off anticoagulation

Outcome

Despite aggressive treatment:

• Visual acuity at 24 hours: Count fingers at 1 foot (minimal improvement)
• Visual acuity at 1 week: 20/400 (severe permanent vision loss)
• Prognosis: Poor - most patients do not recover useful vision

Secondary Prevention

Essential Workup (CRAO = TIA equivalent):

• Complete stroke workup indicated
• Evaluate for other vascular disease
• Aggressive risk factor modification

Treatment:

• Resume anticoagulation for atrial fibrillation
• Statin therapy (high-intensity)
• Blood pressure control
• Carotid intervention considered (vascular surgery referral)

Disposition

• Admission for stroke workup
• Ophthalmology follow-up arranged
• Discharged on apixaban (transitioned from warfarin)
• Close follow-up for carotid disease

Teaching Points

1. CRAO = ocular stroke: Same risk factors, same urgency, same workup
2. Time is vision: 90-100 minutes of retinal ischemia tolerance; treat immediately
3. Cherry-red spot is pathognomonic: Normal choroid visible through thin macula surrounded by ischemic pale retina
4. APD confirms optic nerve/retinal pathology: Differentiates from cortical blindness
5. Treatment options limited: Ocular massage, IOP lowering, hyperoxia; most don't recover
6. Secondary prevention is critical: Full stroke workup; treat underlying cause
7. Consider GCA: In patients >50 with CRAO; check ESR; temporal artery biopsy if suspected

Clinical Image

Image Description: Fundoscopic photograph demonstrating central retinal artery occlusion with the characteristic "cherry-red spot" at the macula (arrow) surrounded by pale, opaque retina due to ischemic edema.

Attribution: Image from Wikimedia Commons, Cherry red spot CRAO. Licensed under CC BY-SA 4.0. Source: https://commons.wikimedia.org/wiki/File:Central_retinal_artery_occlusion.jpg

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