Convergence Insufficiency

Convergence insufficiency (CI) is a common binocular vision disorder where the eyes have difficulty working together when focusing on nearby objects. This makes reading, computer work, and other close tasks uncomfortable and difficult.

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Understanding Convergence

What Is Convergence?

When you look at something close:

• Both eyes must turn inward (converge)
• This keeps the object single (not double)
• Requires coordination between the eye muscles

What Goes Wrong in CI

• Eyes don't turn inward enough
• Or cannot sustain convergence
• The brain must work harder to maintain single vision
• Results in strain, fatigue, and symptoms

Symptoms

Visual Symptoms

• Double vision when reading (may be intermittent)
• Blurred vision at near
• Words appear to move or float on the page
• Eyes feel "tired" or strained
• Difficulty shifting focus between near and far

Physical Symptoms

• Headaches (especially after reading)
• Eye fatigue
• Pulling sensation around the eyes
• Sore eyes

Reading/Learning Symptoms

• Difficulty concentrating on near tasks
• Losing place while reading
• Reading slowly
• Needing to re-read material
• Avoiding near work
• Words running together

Behavioral Signs (Especially in Children)

• Covers one eye when reading
• Avoids homework or reading
• Short attention span for near work
• Appears inattentive during sustained reading or homework
• Better performance with auditory vs. visual learning

Convergence Insufficiency, ADHD, and Schoolwork

CI can make close work uncomfortable enough that a child loses place, takes frequent breaks, avoids reading, or has trouble sustaining attention during homework. Those behaviors can overlap with concerns that lead families to ask about ADHD.

CI and ADHD require different evaluations and can occur in the same child. A binocular vision examination checks eye alignment, near point of convergence, and fusional vergence. An ADHD assessment considers attention and behavior across settings and activities, including tasks that do not depend on near vision.

Treating CI can improve the eye-coordination measurements used to diagnose it and may make near work more comfortable. In the CITT-ART randomized trial, vergence and accommodative therapy did not outperform placebo therapy on standardized reading or attention outcomes. Families should continue educational or ADHD care when those concerns remain.

Who Gets Convergence Insufficiency?

• Common in children and young adults
• Affects an estimated 2-13% of the population
• Can develop after:
  • Head injury/concussion
  • Illness
  • Fatigue or stress
• May worsen with increased near work (screens, schoolwork)

How CI Is Diagnosed

Comprehensive Eye Exam

• Visual acuity testing
• Refraction (glasses check)
• Assessment of eye alignment

Specific Tests for CI

Near Point of Convergence (NPC):

• Measures how close a target can move before the eyes lose alignment or the patient sees double
• Records both the break point and recovery point
• Reference ranges vary with age, target, and testing method

Positive Fusional Vergence:

• How much can eyes converge using prisms?
• Reduced in CI

Cover Test:

• Evaluates eye alignment
• May show exophoria (outward drift) at near

Criteria for Diagnosis

• Greater outward eye alignment at near than at distance
• Receded near point of convergence for the testing method
• Reduced positive fusional vergence
• Symptoms during reading or other near work

Convergence Insufficiency Treatment

Office-Based Vergence and Accommodative Therapy

For children with symptomatic CI, office-based vision therapy with home reinforcement has the strongest randomized-trial evidence for improving near point of convergence and positive fusional vergence.

What it involves:

• Weekly sessions with a trained therapist, commonly for 12 to 16 weeks in clinical trials
• Exercises to improve convergence ability
• Home practice between sessions
• Progressive difficulty as skills improve

Exercises include:

• Pencil push-ups
• Brock string exercises
• Vectograms
• Computer-based vergence training

Prism Glasses

• Base-in prism reduces the convergence demand while the glasses are worn
• A randomized trial in children found base-in reading prism was no more effective than placebo glasses for symptoms or convergence measurements
• A clinician may still consider prism in selected situations after measuring eye alignment and discussing the limits of the evidence

Home-Based Exercises Only

• Pencil push-ups alone underperformed office-based therapy with home reinforcement in the 2008 pediatric CITT trial
• A structured home program may be considered when office therapy is unavailable
• Requires good compliance

Reading Glasses

• A near prescription may reduce visual effort when an accommodative or refractive problem is also present
• The prescription should be based on examination findings and the specific contributing problem

What the CITT Trials Show

The Convergence Insufficiency Treatment Trial research gives a more specific picture than a single success-rate claim:

• 2008 CITT: Among children ages 9 to 17, office-based vergence and accommodative therapy with home reinforcement produced better symptom and clinical outcomes than pencil push-ups, a home computer program, or office placebo therapy after 12 weeks.
• 2019 CITT-ART clinical outcomes: Among children ages 9 to 14, office-based therapy improved objective convergence measures more than placebo therapy. Self-reported symptom scores improved in both groups without a statistically significant between-group difference.
• CITT-ART reading and attention outcomes: The active therapy did not outperform placebo therapy on standardized reading or attention measures after 16 weeks.

These findings support office-based therapy for the eye-coordination disorder itself. They also set a clear boundary around promises about grades, reading achievement, or ADHD symptoms.

Living with CI

While in Treatment

• Take frequent breaks during near work (20-20-20 rule)
• Good lighting
• Proper reading distance and posture
• Use audio options when possible
• Inform teachers about the condition

After Treatment

• Most people maintain improvement
• May need occasional "tune-up" exercises
• Symptoms can recur with fatigue or illness
• Know the exercises to restart if needed

CI and Concussion

CI is common after concussion/mild traumatic brain injury:

• May develop even without prior symptoms
• Can significantly impact recovery
• Treatment is similar to standard CI
• Often improves with vision therapy

Frequently Asked Questions

Is convergence insufficiency a learning disability?

CI is a binocular vision disorder. It can make reading uncomfortable and contribute to losing place, headaches, or task avoidance. A separate educational evaluation is appropriate when reading or learning concerns persist because CI treatment has not been shown to improve standardized reading performance more than placebo therapy.

Can glasses fix convergence insufficiency?

Regular glasses correct refractive blur when a prescription is present. Prism reduces convergence demand while worn, although a pediatric randomized trial found base-in reading prism performed similarly to placebo glasses. Office-based vergence and accommodative therapy has the strongest pediatric evidence for improving clinical convergence measures.

Is CI the same as lazy eye?

No. Lazy eye (amblyopia) is reduced vision in one eye. CI is a coordination problem between the two eyes. Both are binocular vision issues but are different conditions.

How long does vision therapy take?

The main pediatric trials used 12 or 16 weekly office sessions with home reinforcement. The plan may be shorter or longer depending on age, severity, response, access, and whether another binocular or focusing problem is present.

Can CI come back after treatment?

Most people maintain their improvement. However, CI can recur with extreme fatigue, illness, or sometimes after years. If symptoms return, a brief course of exercises often restores function.

Should my child be tested for CI?

Consider testing if your child has:

• Headaches with reading
• Avoids near work
• Attention problems only with visual tasks
• Reading below potential
• Covers one eye to read A regular vision screening may not detect CI. A comprehensive binocular vision evaluation is needed.

References

1. Convergence Insufficiency Treatment Trial Study Group. Randomized clinical trial of treatments for symptomatic convergence insufficiency in children. Arch Ophthalmol. 2008;126(10):1336-1349.
2. Scheiman M, et al. Convergence insufficiency treatment trial (CITT): study design, methods, and baseline data. Ophthalmic Epidemiol. 2008;15(1):24-36.
3. CITT-ART Investigator Group. Treatment of symptomatic convergence insufficiency in children enrolled in the CITT-ART: a randomized clinical trial. Optom Vis Sci. 2019;96(11):825-835.
4. CITT-ART Investigator Group. Effect of vergence/accommodative therapy on reading in children with convergence insufficiency. Optom Vis Sci. 2019;96(11):836-849.
5. CITT-ART Investigator Group. Effect of vergence/accommodative therapy on attention in children with convergence insufficiency. Optom Vis Sci. 2021;98(3):222-233.
6. Scheiman M, et al. Randomised clinical trial of base-in prism reading glasses versus placebo reading glasses for symptomatic convergence insufficiency in children. Br J Ophthalmol. 2005;89(10):1318-1323.
7. American Academy of Ophthalmology. Convergence Insufficiency.
8. National Eye Institute. Convergence Insufficiency.