Central retinal artery occlusion (CRAO) case study
The case
Patient: 62‑year‑old male, retired accountant
Presenting complaint: Sudden, painless loss of vision in the right eye for 2 hours.
History of present illness:
- While watching television, the patient noticed that the right visual field became completely black. He could still perceive light, but no shapes or colors.
- The loss was instantaneous, with no preceding trauma, headache, or ocular pain.
- No similar episodes in the past.
- He reports a brief “whooshing” sensation in the right ear at the onset, which resolved within a minute.
Past medical history:
- Hypertension for 12 years, on amlodipine 10 mg daily (BP usually 140/85 mm Hg).
- Type 2 diabetes mellitus for 8 years, on metformin 500 mg twice daily; last HbA1c 7.8 % (3 months ago).
- Hyperlipidaemia, on atorvastatin 40 mg nightly.
- Former smoker, 20 pack‑years, quit 5 years ago.
Family history: Father died of myocardial infarction at 68 years; mother had stroke at 72 years.
Medications: Amlodipine 10 mg OD, metformin 500 mg BD, atorvastatin 40 mg HS, aspirin 81 mg OD (started 2 months ago after a carotid Doppler showed 30 % stenosis).
Allergies: No known drug allergies.
Social history: Lives with wife, independent in activities of daily living, occasional alcohol (1–2 drinks/week).
Examination
| Parameter | Value |
|---|---|
| General | Alert, oriented, no distress |
| Vital signs | BP 152/90 mm Hg (right arm, seated), HR 78 bpm regular, RR 16 /min, Temp 36.8 °C, SpO₂ 98 % on room air |
| Cardiac | Normal S1, S2, no murmurs |
| Neurological | Cranial nerves II–XII: Right eye – no light perception, afferent pupillary defect (RAPD) present; left eye normal. No facial weakness, limb power 5/5, sensation intact, gait steady. |
| Ophthalmic – Right eye | Visual acuity: No light perception (NLP). Pupils: 4 mm, sluggish reaction, RAPD. Conjunctiva: clear. Cornea: clear. Anterior chamber: quiet. Intra‑ocular pressure (IOP): 14 mm Hg (Goldmann). Fundus (direct ophthalmoscopy): Diffuse retinal pallor with a “cherry‑red spot” at the macula; attenuated retinal arteries; no vitreous hemorrhage. |
| Ophthalmic – Left eye | Visual acuity 6/6, normal pupil reaction, fundus unremarkable. |
| Vascular | Carotid auscultation: bruit over right carotid sinus. Peripheral pulses palpable, no edema. |
Initial investigations
| Test | Result |
|---|---|
| Random blood glucose | 156 mg/dL |
| HbA1c (3 months) | 7.8 % |
| Lipid profile | Total cholesterol 210 mg/dL, LDL‑C 140 mg/dL, HDL‑C 38 mg/dL, Triglycerides 180 mg/dL |
| Complete blood count | Hb 13.5 g/dL, WBC 7.8 × 10⁹/L, Platelets 240 × 10⁹/L |
| ESR, CRP | ESR 12 mm/h, CRP 3 mg/L (both within normal) |
| ECG | Normal sinus rhythm, no ST‑T changes |
| Carotid Doppler (performed 1 month ago) | Right internal carotid artery (ICA) plaque causing 30 % stenosis; left ICA normal |
| Urgent non‑contrast CT brain | No acute haemorrhage or infarct |
| Ocular ultrasound (B‑scan) | No vitreous or retinal detachment; optic nerve sheath diameter normal |
| Fluorescein angiography (performed 1 hour after presentation) | Delayed arterial filling of the central retinal artery; prolonged arm‑retina time (≈ 30 seconds) with a “cattle‑track” pattern; macular cherry‑red spot persists. |
Questions
- What is the most likely diagnosis?
- Which clinical findings and investigations specifically point toward this diagnosis, and why?
- List the immediate investigations that should be performed in a patient with suspected central retinal artery occlusion (CRAO).
- Outline the evidence‑based acute management steps for CRAO, including any time‑sensitive interventions.
- Discuss the short‑ and long‑term ocular and systemic complications that may follow CRAO.
Answers
1. What is the most likely diagnosis?
Central retinal artery occlusion (CRAO).
The presentation of sudden, painless, unilateral vision loss with a classic fundoscopic “cherry‑red spot” and retinal pallor is pathognomonic for CRAO. The presence of a relative afferent pupillary defect (RAPD) confirms severe optic nerve/retinal ischemia on the affected side.
2. Which clinical findings and investigations specifically point toward this diagnosis, and why?
| Finding | Reason it supports CRAO |
|---|---|
| Sudden, painless, monocular vision loss | Vascular occlusion of the central retinal artery causes instantaneous loss of retinal perfusion; pain is absent because the retina lacks pain receptors. |
| No light perception (NLP) with RAPD | RAPD indicates asymmetric afferent input; in CRAO the retina is ischemic, producing a marked RAPD. |
| Fundus: diffuse retinal pallor + cherry‑red spot | The inner retina becomes edematous and opaque (pallor) while the fovea, supplied by the choroidal circulation, remains relatively red, creating the classic “cherry‑red spot.” |
| Attenuated retinal arteries | Chronic hypoperfusion leads to narrowing of the arterioles visible on ophthalmoscopy. |
| Fluorescein angiography: delayed arterial filling, prolonged arm‑retina time | Direct visualization of impaired arterial inflow confirms occlusion of the central retinal artery. |
| Risk‑factor profile (HTN, DM, hyperlipidaemia, carotid plaque) | These atherosclerotic risk factors are the most common sources of emboli to the retinal artery. |
| Carotid bruit & 30 % ICA plaque | Plaque can generate cholesterol or platelet‑fibrin emboli that travel via the ophthalmic artery to the central retinal artery. |
| Normal CT brain | Excludes intracranial haemorrhage or large‑vessel stroke, focusing the diagnosis on the ocular circulation. |
Together, the clinical picture and targeted investigations fulfill the diagnostic criteria for CRAO.
3. List the immediate investigations that should be performed in a patient with suspected CRAO.
- Ophthalmic examination – Visual acuity, pupil reactions (RAPD), intra‑ocular pressure, slit‑lamp, dilated fundus examination.
- Fundus photography – Baseline documentation of retinal pallor and cherry‑red spot.
- Fluorescein angiography (FA) – To confirm delayed arterial filling and to rule out vasculitis or other retinal vascular disorders.
- Optical coherence tomography (OCT) – Shows hyper‑reflectivity and thickening of the inner retinal layers in the acute phase.
- Carotid duplex ultrasonography – Detects ipsilateral carotid atherosclerotic disease (≥ 50 % stenosis warrants urgent intervention).
- Cardiac evaluation – 12‑lead ECG, transthoracic echocardiography (or trans‑esophageal if indicated) to look for cardiac sources of emboli (e.g., atrial fibrillation, valvular disease, mural thrombus).
- Blood tests – CBC, fasting lipid profile, HbA1c, coagulation profile, ESR/CRP (to exclude inflammatory vasculitis).
- Urgent non‑contrast CT head – Excludes intracranial haemorrhage before any systemic thrombolysis is considered (if indicated).
Guidelines (American Academy of Ophthalmology – AAO, 2022) recommend that these investigations be initiated within the first hour of presentation.
4. Outline the evidence‑based acute management steps for CRAO, including any time‑sensitive interventions.
Key principle: Retinal ganglion cells begin irreversible damage after ≈ 100 minutes of complete ischemia; therefore, rapid reperfusion is critical.
| Step | Intervention | Details & Evidence |
|---|---|---|
| A. Immediate ocular massage | Digital or intra‑ocular pressure (IOP) lowering massage. | Apply intermittent pressure (10 seconds on, 10 seconds off) for 5–10 minutes. Small case series (AAO 2022) suggest modest visual improvement if performed within 30 minutes. |
| B. IOP reduction | Topical agents: timolol 0.5 % BID, apraclonidine 1 % BID; systemic: oral acetazolamide 500 mg PO (or IV 500 mg if unable to swallow). | Lowering IOP creates a pressure gradient favoring arterial inflow. |
| C. Anterior chamber paracentesis | Remove 0.1–0.2 mL aqueous humor under sterile conditions. | Immediate IOP drop; meta‑analysis (2021) shows visual gain in ≈ 15 % of cases when performed within 2 hours. |
| D. Hyper‑oxygen therapy | 100 % oxygen via non‑rebreather mask at 10 L/min for 30 minutes. | Increases dissolved O₂ in plasma, potentially sustaining the ischemic retina. |
| E. Intravenous thrombolysis (IV tPA) | Consider if presentation < 4.5 hours and no contraindications; dose 0.9 mg/kg (10 % bolus, remainder over 60 min). | European Stroke Organisation (ESO) 2023 guideline: IV tPA may be offered in selected CRAO patients when stroke team available, though evidence remains Level C. |
| F. Intra‑arterial thrombolysis (IAT) | Catheter‑directed delivery of urokinase or tPA into the ophthalmic artery. | Small RCT (EAGLE, 2020) showed no significant benefit over standard care; currently not routinely recommended but may be considered in specialized centres within 6 hours. |
| G. Antiplatelet therapy | Initiate aspirin 325 mg loading, then 81–325 mg daily. | Reduces risk of subsequent embolic events; guideline (AAO 2022) recommends lifelong antiplatelet unless contraindicated. |
| H. Systemic risk‑factor optimisation | Tight BP control (< 130/80 mm Hg), statin intensification (e.g., atorvastatin 80 mg), glycaemic control (HbA1c < 7 %). | Reduces recurrence risk; aligns with ACC/AHA 2023 secondary prevention recommendations. |
| I. Referral | Immediate ophthalmology and stroke‑team involvement. | Multidisciplinary care improves outcomes and ensures secondary prevention. |
Algorithmic timeline (AAO 2022):
- 0–15 min: Visual assessment, fundus exam, start ocular massage & IOP‑lowering drops.
- 15–30 min: Consider anterior chamber paracentesis if no improvement.
- 30–60 min: Initiate hyper‑oxygen therapy; arrange urgent FA/OCT.
- ≤ 4.5 h: Evaluate eligibility for IV tPA (stroke team).
- ≤ 6 h: If centre equipped, discuss IAT.
5. Discuss the short‑ and long‑term ocular and systemic complications that may follow CRAO.
| Complication | Short‑term (days–weeks) | Long‑term (months–years) | Clinical relevance |
|---|---|---|---|
| Permanent visual loss | Most patients retain ≤ 20/400 vision; many become legally blind in the affected eye. | No spontaneous recovery beyond 2 weeks; visual field defects (central scotoma) persist. | Major morbidity; impacts driving, independence. |
| Neovascular glaucoma (NVG) | Neovascularisation of the iris (rubeosis iridis) may appear 4–6 weeks after CRAO. | Elevated IOP, painful red eye, rapid vision loss. | Requires pan‑retinal photocoagulation (PRP) and IOP‑lowering surgery. |
| Retinal atrophy | Progressive thinning of inner retinal layers on OCT after 1–3 months. | Permanent structural loss; correlates with visual outcome. | No specific therapy; underscores need for early reperfusion. |
| Ischemic optic neuropathy | Rare; may present with optic disc pallor within weeks. | Persistent optic disc cupping, further visual decline. | Differentiated from CRAO by disc appearance; managed conservatively. |
| Systemic embolic events | Up to 20 % experience a stroke or myocardial infarction within 90 days (CRAO considered a stroke equivalent). | Ongoing risk of recurrent emboli if atherosclerotic source not treated. | Necessitates aggressive secondary prevention (antiplatelet, statin, carotid endarterectomy if ≥ 70 % stenosis). |
| Carotid artery disease progression | Plaque may enlarge; symptomatic carotid stenosis may develop. | Indications for carotid endarterectomy or stenting per 2023 ESC guidelines. | Regular duplex surveillance every 6–12 months. |
| Psychological impact | Depression, anxiety due to sudden vision loss. | Chronic adjustment disorder if visual disability persists. | Referral to counseling/rehabilitation services. |
Key learning points
- CRAO presents with instantaneous, painless monocular vision loss; the hallmark fundus sign is a cherry‑red spot with diffuse retinal pallor.
- Time is retina: irreversible retinal ganglion cell death begins after ~100 minutes; therefore, reperfusion attempts must start within the first hour.
- Immediate ocular measures (digital massage, IOP‑lowering drops, anterior chamber paracentesis) are low‑risk and should be performed while arranging definitive imaging.
- Systemic evaluation (carotid Doppler, cardiac work‑up, vascular risk‑factor optimisation) is essential because CRAO is a stroke equivalent with high risk of subsequent cerebrovascular events.
- IV thrombolysis may be considered within 4.5 hours in selected patients, but evidence remains limited; intra‑arterial thrombolysis is not routinely recommended.
- Neovascular glaucoma is a feared ocular complication that can develop weeks after CRAO; early detection and PRP are crucial.
- Long‑term visual prognosis is generally poor; visual rehabilitation and psychosocial support are integral parts of care.
Practice MCQs
1. A 58‑year‑old woman presents with sudden, painless loss of vision in the left eye. Fundoscopy shows a pale retina with a cherry‑red spot. Which of the following is the most appropriate immediate step?
A. Start high‑dose oral prednisone.
B. Perform digital ocular massage and give topical timolol.
C. Order a magnetic resonance angiography of the brain.
D. Schedule elective cataract surgery.
Answer: B — Digital ocular massage and topical IOP‑lowering agents are the first‑line emergency measures for CRAO, aiming to restore retinal perfusion within the critical time window.
2. In a patient with confirmed central retinal artery occlusion, which systemic investigation is most strongly indicated to identify the embolic source?
A. Serum antinuclear antibody panel.
B. Carotid duplex ultrasonography.
C. Lumbar puncture.
D. Thyroid function tests.
Answer: B — Carotid duplex is the investigation of choice to detect ipsilateral atherosclerotic plaque, the common source of emboli causing CRAO.
3. Which of the following statements about neovascular glaucoma (NVG) following CRAO is correct?
A. NVG typically develops within the first 24 hours after CRAO.
B. Pan‑retinal photocoagulation (PRP) is ineffective in preventing NVG.
C. NVG is associated with new vessels on the iris and angle, leading to elevated IOP.
D. NVG resolves spontaneously without treatment in most cases.
Answer: C — NVG after CRAO is characterized by rubeosis iridis and angle neovascularisation, causing secondary angle‑closure glaucoma; early PRP can help prevent its
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