How to assess vision in an emergency?

How to Assess Vision in an Emergency Setting

In an emergency, immediately measure visual acuity with current correction at distance (and near when appropriate), assess pupillary function including relative afferent pupillary defect, perform external examination, and conduct fundoscopy—these core elements identify vision-threatening conditions and guide urgent management decisions. 1

Essential Initial Assessment Components

Visual Acuity Measurement

• Document visual acuity with current correction at distance as the first priority—this is one of the most sensitive techniques for detecting eye abnormalities and establishes a critical baseline 1
• Record the power of any current correction being worn 1
• For patients with acuity less than 20/100, extend the measurement range by using portable test charts at closer distances (e.g., ETDRS chart at 1 meter) to avoid imprecise "count fingers" notation 1
• If standard charts cannot be used, quantify "counting fingers" as approximately 0.014 and "hand motion" as approximately 0.005 for more precise documentation 2
• Test both monocularly and binocularly, as binocular testing may reveal functional differences 1

Pupillary Examination

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

External and Anterior Segment Examination

• Perform external examination including eyelid position, lashes, lacrimal apparatus, globe position, and facial features 1
• Assess conjunctiva, sclera, cornea, and anterior chamber 1
• Check red reflex bilaterally—any asymmetry in color, brightness, or size indicates serious pathology including retinoblastoma, cataracts, or retinal detachment 1
• Use a direct ophthalmoscope from 2-3 feet away in a darkened room to view both red reflexes simultaneously 1

Ocular Motility and Alignment

• Test ocular alignment and motility, including cover/uncover test and assessment of ductions and versions 1
• Ocular misalignment can indicate serious orbital, intraocular, or intracranial disease 1

Fundoscopic Examination

• Examine the fundus including vitreous, retina (posterior pole and periphery), vasculature, and optic nerve 1
• In acute vision loss, look specifically for retinal whitening, cherry-red spot (central retinal artery occlusion), retinal hemorrhages, cotton wool spots, emboli, and vascular "boxcarring" 1
• Optimal examination requires dilation, though initial assessment can begin undilated 1

Visual Field Assessment

• Perform visual fields by confrontation as part of the initial examination 1
• This rapid bedside test can identify hemianopsias, quadrantanopsias, or severe peripheral field loss 1

Time-Critical Conditions Requiring Immediate Recognition

Central Retinal Artery Occlusion (CRAO)

• Transfer immediately to stroke center/emergency department without delay if CRAO suspected—this is an ocular stroke requiring evaluation within 4.5 hours for potential thrombolysis 3
• The risk of concurrent cerebral stroke is 19-25%, with highest stroke risk in the first 7 days 1, 3
• Communicate clearly that the patient has experienced an "eye stroke" to ensure appropriate triage 3

Giant Cell Arteritis Screening

• In patients over 50 years with acute vision loss, immediately screen for giant cell arteritis symptoms (headache, scalp tenderness, jaw claudication, temporal tenderness, malaise) 1
• This is critical to prevent vision loss in the contralateral eye 3
• Obtain ESR and CRP urgently if GCA suspected 3

Intraocular Pressure Measurement

• Measure intraocular pressure, preferably with contact applanation (Goldmann tonometer) 1
• Defer contact tonometry if suspected ocular infection or corneal trauma 1
• Perform gonioscopy when neovascularization or elevated pressure is present or suspected 1

Documentation Priorities

• Always document visual acuity or subjective vision—this is vital for medicolegal purposes and clinical decision-making 4
• Record testing distance, correction used, and whether testing was monocular or binocular 1
• Note any asymmetries, patient behaviors during testing (head turns, searching movements), or patterns of missed letters that suggest scotomas 1

Common Pitfalls to Avoid

• Do not delay transfer to emergency department to obtain additional outpatient testing when time-critical conditions like CRAO are suspected 1
• Avoid rushed testing—allow patients time to fixate, as measured acuity may vary with fixation shifts 1
• Do not use imprecise notations like "count fingers" when quantifiable measurements are possible with closer testing distances 1, 2
• In children under 3 years, assess whether each eye can fixate, maintain fixation, and follow objects—inability to do so indicates significant visual impairment (though disinterest can mimic poor vision) 1

Special Considerations for Pediatric Patients

• For children 3 years and older, use age-appropriate visual acuity testing with picture cards, wall charts, or vision testing machines 1
• 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 in all children 1