15/02/2026
Exophoria — concise clinical overview.
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Definition
Exophoria is a latent outward deviation of the visual axes that becomes manifest only when binocular fusion is disrupted (e.g., during a cover test). Under normal viewing, fusional convergence maintains alignment.
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Pathophysiology
It represents an imbalance where divergence tone exceeds convergence tone. Control depends on fusional vergence reserves and sensory fusion.
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Etiology / Associations
• Physiological variation (common at near)
• Prolonged near work / digital eye strain
• Uncorrected refractive error (especially hyperopia or under-corrected myopia)
• Convergence insufficiency
• Post-illness fatigue or decompensation
• Occasionally associated with systemic fatigue or stress
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Symptoms (when decompensated)
• Asthenopia (eye strain)
• Intermittent blur, especially at near
• Headaches (frontal)
• Intermittent diplopia
• Difficulty sustaining reading
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Clinical Evaluation
1. Cover–uncover & alternate cover test → quantifies deviation
2. Prism cover test → magnitude in prism diopters
3. Near point of convergence (NPC)
4. Fusional vergence ranges (PFV/NFV)
5. AC/A ratio when indicated
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Management
Asymptomatic small exophoria → no treatment, observation
Symptomatic / decompensated:
• ✔️ Optimal refractive correction
• ✔️ Vision therapy / orthoptic exercises (e.g., convergence training)
• ✔️ Prism correction (base-in) in selected cases
• ✔️ Ergonomic modifications for near work
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Prognosis
Generally excellent. Most cases remain stable or improve with appropriate binocular vision therapy.