Convergence Insufficiency (CI)

By: Carmen Willings
teachingvisuallyimpaired.com
Updated June 13, 2025
Convergence Insufficiency (CI) is a binocular vision disorder that affects a person's ability to perform tasks that require near vision. It is becoming more widely recognized by the public. Students with CI may have a normal eye exam and still experience significant difficulty with close-up tasks such as reading, writing, using a computer, playing video games, or doing crafts.
According to the Optometrists Network, Convergence Insufficiency is “the leading cause of eyestrain, blurred vision, double vision (diplopia), and/or headaches."

​What Is Convergence Insufficiency?

​CI occurs when the eyes do not work together properly at near distances. It is a problem with eye teaming—specifically, a tendency for the eyes to drift outward (a condition called exophoria at near) when looking at close objects. To maintain single, clear vision, the person must work harder to pull their eyes inward (to converge). This extra effort often leads to uncomfortable symptoms. Even if a student passes a 20/20 vision screening, they can still have CI, which impacts reading, learning, and working comfortably at close distances.

​Common Symptoms of CI

​Symptoms may appear during or after close-up tasks and may include:
  • Eye strain
  • Headaches
  • Blurred or double vision (diplopia)
  • Sleepiness or fatigue when reading
  • Difficulty concentrating
  • Print that seems to move or “swim” on the page
  • Poor reading comprehension over time
  • Frequently losing one’s place while reading
  • Squinting, rubbing, closing, or covering one eye
These symptoms may worsen with illness, lack of sleep, anxiety, or extended periods of near work.

​Potential Effects of Untreated CI

Without treatment, CI can cause a person to suppress vision in one eye, meaning the brain ignores input from that eye. This can lead to:
  • Loss of binocular vision
  • Reduced depth perception
  • Difficulties with coordination and sports
  • Poor judgment of distances
  • Increased motion sickness
  • Difficulty making eye contact

​Diagnosis and Treatment

​An optometrist can diagnose CI through a binocular vision evaluation. There are two main types of treatment:
  • Passive treatment: Prism lenses to reduce symptoms
  • Active treatment: Vision therapy, typically office-based with reinforcement at home
Surgery is rarely, if ever, used to treat CI.

Educational Implications

A diagnosis of Convergence Insufficiency does not automatically qualify a student for school-based vision services. Eligibility depends on how the condition affects educational access and performance.
​
If a student is found eligible, it’s important to note that vision therapy is a medical treatment. It is not provided by Teachers of Students with Visual Impairments (TVIs). Vision therapy must be administered by, or under the supervision of, an optometrist or other trained professional. 

Classroom Accommodations

The optometrists may recommend simple classroom accommodations that can help reduce symptoms and support learning. These may include:
  • Using a line guide or bookmark while reading
  • Reading or writing on a slant board or inclined surface
  • Providing copies of board notes
  • Seating the student closer to the front of the room or instructional area
These simple accommodations can be implemented by teachers and school staff regardless of eligibility for vision services.

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