How do you assess vision in the emergency department?

Vision Assessment in the Emergency Department

Begin with visual acuity testing using current correction at distance, as this is the single most sensitive technique for detecting eye abnormalities and establishes a critical baseline for all subsequent evaluation. 1

Essential Initial Assessment Sequence

Visual Acuity Testing (First Priority)

• Measure distance visual acuity with any current correction the patient is wearing, documenting the power of that correction 1, 2
• Test each eye separately (monocularly) and then together (binocularly) 1
• For patients with acuity worse than 20/100, move the test chart closer rather than recording imprecise measurements like "counts fingers" 1
• Use portable test charts at bedside when patients cannot ambulate to standard 20-foot testing distance 1
• Consider smartphone-based visual acuity apps, which have been shown to be more accurate than Snellen testing by ED staff 3

Pupillary Examination (Critical for Neurologic Assessment)

• Assess for relative afferent pupillary defect (RAPD), which indicates significant retinal or optic nerve dysfunction 1, 2
• Evaluate pupil size, shape, and reactivity to light in both eyes 1, 2
• Slow or poorly reactive pupils suggest significant retinal or optic nerve pathology 2, 1
• Pupil asymmetry greater than 1mm may indicate neurologic disorders 2

Red Reflex Testing (Detects Vision-Threatening Pathology)

• Perform bilateral red reflex examination; any asymmetry in color, brightness, or size indicates serious pathology requiring immediate ophthalmology consultation 1, 2
• Use direct ophthalmoscope in a darkened room from 2-3 feet away 2
• A white pupil (leukocoria) suggests possible retinoblastoma or other serious pathology 2

Visual Fields by Confrontation

• Test all four quadrants to identify hemianopsias, quadrantanopsias, or severe peripheral field loss 1, 2
• This simple bedside test can detect stroke, increased intracranial pressure, or retinal detachment 2

External and Motility Examination

• Inspect eyelid position, lashes, lacrimal apparatus, globe position, and facial features 1, 2
• Assess ocular alignment and motility using cover/uncover test and versions 2
• Any eye movement during cover testing indicates misalignment 2

Intraocular Pressure Measurement

• Measure IOP preferably with contact applanation (Goldmann tonometer) 1, 2
• Defer contact tonometry if suspected ocular infection or corneal trauma is present 1, 2
• Elevated pressure may indicate acute angle-closure glaucoma, a true emergency 2

Fundus Examination

• Examine vitreous, retina (including posterior pole and periphery), vasculature, and optic nerve 1, 2
• Look specifically for retinal detachment, vitreous hemorrhage, or optic nerve abnormalities 2

Time-Critical Conditions Requiring Immediate Recognition

Central Retinal Artery Occlusion (Ocular Stroke)

• Transfer patients with suspected CRAO immediately to a stroke center without delay, as this requires evaluation within 4.5 hours for potential thrombolysis 1
• This represents an ophthalmologic emergency equivalent to cerebral stroke 1

Giant Cell Arteritis

• In patients over 50 years with acute vision loss, immediately screen for giant cell arteritis symptoms including headache, scalp tenderness, jaw claudication, temporal tenderness, and malaise 1
• This prevents vision loss in the contralateral eye, which can occur within days 1

Special Considerations for Pediatric Patients

Children 3 Years and Older

• Use age-appropriate visual acuity testing with picture cards (Allen figures, LEA symbols), HOTV, tumbling E, or wall charts 1, 2
• Refer if fewer than 4 of 6 correct on the 20/40 line (20/30 for children 6 years and older) 2
• Refer for any two-line difference between eyes, even within passing range 2

Children Under 3 Years

• Assess whether each eye can fixate on an object, maintain fixation, and follow the object into various gaze positions 2
• Test binocularly and then monocularly 2
• Inability to follow these maneuvers indicates significant visual impairment 2

General Pediatric Considerations

• Children under 7 years with suspected vision problems should be discussed with ophthalmology for severity grading 1
• Use linear or crowded optotypes for best accuracy 1
• The child must be awake and alert, as disinterest can mimic poor vision 2

Common Pitfalls to Avoid

• Never skip visual acuity documentation—it is medicolegally essential and guides all subsequent management 1, 2
• Do not rely solely on patient's subjective report of vision; objective measurement is mandatory 2
• Avoid testing through pinholes initially in the ED setting; test with current correction first 1
• Do not assume symmetric pupils are normal; check reactivity and for RAPD 1
• Remember that normal visual acuity does not exclude serious pathology like retinal detachment or optic neuritis 4