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.

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 "lazy" or inattentive (may be misdiagnosed as ADHD)
• Better performance with auditory vs. visual learning

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):

• How close can you bring an object before seeing double?
• Normal: 6-10 cm from nose
• CI: Often 10+ cm (sometimes 20-30 cm)

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

• Receded near point of convergence (>10 cm)
• Reduced positive fusional vergence
• Symptomatic

Treatment Options

Vision Therapy (Most Effective)

Office-based vision therapy with home reinforcement:

What it involves:

• Weekly sessions with trained therapist (12-24 weeks)
• Exercises to improve convergence ability
• Home practice between sessions
• Progressive difficulty as skills improve

Effectiveness:

• 75-80% success rate
• Proven in randomized controlled trials (CITT study)
• Benefits maintained long-term

Exercises include:

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

Prism Glasses

• Can provide symptom relief
• Base-in prisms ease convergence demand
• Don't fix the underlying problem
• May be useful adjunct to therapy

Home-Based Exercises Only

• Less effective than office-based therapy
• Better than no treatment
• May be option when therapy not available
• Requires good compliance

Reading Glasses

• Reducing accommodation may reduce convergence demand
• Not treating the problem directly
• May help some patients

The CITT Study

The Convergence Insufficiency Treatment Trial showed:

• Office-based vision therapy is most effective
• 75% success rate with therapy
• Home exercises alone: ~40% success
• Pencil push-ups alone: ~43% success
• Placebo therapy: ~35% success

This landmark study established vision therapy as evidence-based treatment.

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?

No, CI is a vision problem, not a learning disability. However, it can cause symptoms that look like learning problems—difficulty reading, poor concentration, avoiding schoolwork. Treating CI often dramatically improves these issues.

Can glasses fix convergence insufficiency?

Regular glasses correct blur but don't treat CI. Prism glasses can help manage symptoms but don't fix the underlying problem. Vision therapy is the most effective treatment.

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?

Typically 12-24 weekly sessions, plus daily home exercises. Most patients notice improvement within several weeks, with continued gains over the treatment period.

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—comprehensive evaluation is needed.

References