What is the first line of management for a 55-year-old male patient presenting with sudden severe unilateral pain in the right eye and loss of vision?

Immediate Management of Sudden Severe Unilateral Eye Pain with Vision Loss

This patient requires immediate emergency department or stroke center referral within 24 hours without delay for additional outpatient testing, as this presentation represents a potential ocular emergency that could be acute angle-closure glaucoma, retinal artery occlusion (ocular stroke), or giant cell arteritis—all of which are time-sensitive, vision-threatening conditions. 1, 2

Critical First Steps Before Referral

While arranging immediate transfer, perform these rapid assessments:

• Check intraocular pressure (IOP) if equipment is available—markedly elevated IOP (>40 mmHg) with a mid-dilated, non-reactive pupil suggests acute angle-closure glaucoma 2, 3
• Assess visual acuity in both eyes to document baseline function 4, 3
• Examine the pupil for mid-dilation and lack of reactivity (angle-closure) versus relative afferent pupillary defect (arterial occlusion or optic neuritis) 2, 5
• Screen for giant cell arteritis if patient is over 50 years old by asking about jaw claudication, scalp tenderness, temporal headaches, and constitutional symptoms 6, 2

Immediate Treatment Considerations

If Acute Angle-Closure Glaucoma is Suspected:

Initiate medical therapy immediately while arranging transfer:

• Pilocarpine 2% eye drops to constrict the pupil and open the angle 7, 2
• Oral or intravenous acetazolamide (500 mg) to rapidly lower IOP 2, 3
• Intravenous mannitol (1-2 g/kg) if available for severe IOP elevation 2

If Giant Cell Arteritis is Suspected:

Start empiric high-dose corticosteroids immediately (prednisone 60-80 mg daily or IV methylprednisolone 1000 mg daily) without waiting for biopsy confirmation, as this prevents vision loss in the contralateral eye 6, 1, 2

If Retinal Artery Occlusion (Ocular Stroke) is Suspected:

Do not delay transfer for any interventions—the patient needs stroke center evaluation within 4.5 hours for potential thrombolytic therapy 1, 6

Why Immediate Referral is Non-Negotiable

• Central retinal artery occlusion is a stroke equivalent requiring the same urgency as cerebral stroke, with up to 25% having concurrent silent brain infarction 6, 1
• Acute angle-closure glaucoma causes irreversible optic nerve damage within hours if untreated, with 18% of patients becoming blind and 58% having visual acuity worse than 20/40 even with treatment 4, 2
• Giant cell arteritis has a 50% risk of bilateral blindness if not treated immediately with steroids 6, 2
• The therapeutic window for retinal artery occlusion is 4.5 hours for IV tPA consideration 1

Critical Pitfalls to Avoid

• Never perform extensive ophthalmologic workup before stroke center referral if vascular etiology is suspected—write "Ocular TIA" or "Ocular Stroke" on the referral note 6, 1
• Never delay giant cell arteritis treatment for temporal artery biopsy—empiric steroids should be started immediately in suspected cases 6, 1, 2
• Never assume the patient can wait until morning or for a routine ophthalmology appointment—all three major diagnoses require same-day emergency evaluation 1, 2, 3
• Never miss checking inflammatory markers (ESR, CRP) in patients over 50 years old, regardless of whether classic giant cell arteritis symptoms are present 6, 1

What the Emergency Department Will Do

The stroke center or emergency department will perform:

• Funduscopic examination to confirm diagnosis and exclude hemorrhage 4, 1
• Brain imaging (CT or MRI with diffusion-weighted imaging) to identify concurrent stroke 6, 1
• Vascular imaging (CTA or MRA) to assess carotid stenosis, found in up to 70% of symptomatic retinal vascular events 6, 1
• ESR and CRP in patients over 50 to assess for giant cell arteritis 6, 1
• Gonioscopy if angle-closure glaucoma is suspected 4