What lab workup is recommended for a patient presenting with blurry vision?

Laboratory Workup for Blurry Vision

A comprehensive laboratory workup for blurry vision should be guided by the findings from a complete ocular examination, as blurry vision is primarily evaluated through direct ophthalmologic assessment rather than laboratory testing.

Initial Ocular Examination Components

Before considering laboratory tests, a thorough eye examination should be performed, including:

Essential Components

• Visual acuity with current correction at distance and near 1, 2
• Refraction when indicated 1, 2
• Visual fields by confrontation 1, 2
• External examination (eyelids, lashes, lacrimal apparatus, tear function, globe position) 1, 2
• Pupillary function (size, light response, relative afferent pupillary defect) 1, 2
• Ocular alignment and motility 1, 2
• Slit-lamp biomicroscopy of anterior segment structures 1, 2
• Intraocular pressure measurement (preferably with Goldmann tonometer) 1, 2
• Fundus examination of vitreous, retina, vasculature, and optic nerve 1, 2

Laboratory Testing Based on Clinical Findings

After the ocular examination, laboratory tests should be ordered based on suspected etiologies:

Suspected Inflammatory/Autoimmune Conditions

• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) - particularly important if giant cell arteritis is suspected in patients over 50 with headache, scalp tenderness, or jaw claudication 1
• Angiotensin-converting enzyme (ACE) and soluble interleukin-2 receptor (sIL-2R) - if sarcoidosis is suspected based on granulomatous uveitis findings 3
• Antinuclear antibody (ANA), rheumatoid factor (RF), and anti-neutrophil cytoplasmic antibodies (ANCA) - if systemic autoimmune disease is suspected

Suspected Infectious Causes

• If infectious keratitis is suspected, corneal cultures should be obtained prior to initiating antimicrobial therapy 1
• Blood cultures if endophthalmitis with systemic infection is suspected

Suspected Vascular Causes

• Complete blood count (CBC) - to evaluate for anemia, polycythemia, or leukemia that may affect blood viscosity
• Hemoglobin A1c and fasting glucose - if diabetic retinopathy is suspected
• Lipid panel - if retinal vascular occlusion is suspected 1
• Carotid imaging studies - for patients with suspected transient monocular visual loss from retinal ischemia 4

Suspected Metabolic/Systemic Causes

• Blood pressure measurement - essential in all cases, particularly if hypertensive retinopathy is suspected 5
• Thyroid function tests - if thyroid eye disease is suspected
• Blood glucose - for suspected diabetic eye disease

Special Considerations

• In patients with acute onset of blurry vision with elevated intraocular pressure, prioritize immediate treatment of the pressure before extensive laboratory workup 3
• For patients with transient monocular vision loss, urgent evaluation for carotid disease and giant cell arteritis is warranted 4
• In patients with bilateral blurry vision and headache, consider hypertensive emergency and check blood pressure immediately 5

Follow-up Testing

Based on initial findings, additional specialized testing may be indicated:

• Optical coherence tomography (OCT) for macular or optic nerve evaluation
• Fluorescein angiography for retinal vascular disorders
• Visual field testing by automated perimetry for glaucoma or neurologic visual field defects

Remember that blurry vision is primarily evaluated through direct ophthalmologic assessment, and laboratory testing serves as an adjunct to identify underlying systemic conditions that may be contributing to the visual symptoms.