Treatment of Asthenopia (Eye Strain)
For asthenopia, first identify and correct any underlying refractive error (especially uncorrected hyperopia and astigmatism), then implement convergence exercises if convergence insufficiency is present, and consider environmental modifications including regular breaks and artificial tears for digital device users.
Identify and Correct the Underlying Cause
The most critical first step is determining what is driving the asthenopia, as treatment differs substantially based on etiology 1.
Refractive Error Correction
- Perform cycloplegic refraction to identify any hidden hyperopia or astigmatism that may be causing excessive accommodative demand 2, 3
- Even small amounts of uncorrected hyperopia can cause significant asthenopia and should be corrected with appropriate spectacles 2, 3
- Verify that the optical correction is appropriate for the patient's near work activities 1
- For patients approaching presbyopia, consider bifocal or progressive lenses to reduce accommodative demand 1
Convergence Insufficiency Assessment
If refractive error is corrected but symptoms persist, evaluate for convergence insufficiency 1:
Diagnostic criteria include:
- Exophoria greater at near than distance 1
- Insufficient positive fusional vergence at near (<20 PD mean positive fusional vergence blur) 1
- Distant near point of convergence (>6 cm) 1
Treatment Based on Etiology
For Convergence Insufficiency
Convergence orthoptic exercises are the primary treatment for symptomatic convergence insufficiency 1:
- Office-based training is more effective than home-based exercises in young adults (19-30 years) for improving positive fusional vergence, though results are less consistent in adults than children 1
- Prism reading glasses can be used as an alternative or adjunct to exercises 1
- Strabismus surgery may be considered in select cases, particularly when a manifest distance deviation is present and symptoms are consistent 1
Important caveat: If symptoms are mild, occasional, and not bothersome to the patient, observation without active treatment is appropriate 1
For Digital Eye Strain
When asthenopia is related to prolonged digital device use 4:
- Implement environmental and postural modifications including proper screen positioning and lighting 4
- Recommend regular breaks from screen time (though the specific 20-20-20 rule lacks strong evidence for symptom reduction) 5
- Prescribe artificial tears/lubricants to address concurrent dry eye symptoms, which commonly accompany digital asthenopia 4
- These measures have been shown to improve both subjective symptoms and objective ocular surface changes in users working >2 hours on computers 4
For Accommodative Spasm
If cycloplegic refraction reveals significant accommodative spasm 2:
- Prescribe appropriate spectacle correction for any underlying hyperopia discovered during cycloplegia 2
- Correcting even small amounts of hyperopia reduces accommodative demand and prevents spasm recurrence 2
Common Pitfalls to Avoid
- Never assume asthenopia is purely functional without ruling out organic causes including dry eye, thyroid eye disease, myasthenia gravis, or neurogenic conditions 3
- Do not prescribe treatment without first performing a comprehensive sensorimotor evaluation and assessing refractive status 1
- Avoid dismissing mild symptoms in patients with convergence insufficiency, as treatment objectives are symptom-directed and should focus on resolution of asthenopia and improved comfort with near work 1
- Remember that accommodative and fusional defects often coexist with refractive errors, requiring combined treatment approaches 3
Monitoring and Follow-up
- Quantify symptoms using validated tools such as the Convergence Insufficiency Symptom Survey 1
- For convergence insufficiency, treatment outcomes should target resolution of asthenopia, control of diplopia at near, and improvement in binocular function 1
- Reassess if symptoms persist despite appropriate correction, as this may indicate an alternative or additional diagnosis 3