What is Convergence Insufficiency (CI)?

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Convergence Insufficiency (CI) is the leading cause of eyestrain, blurred vision, double vision (diplopia), and/or headaches.¹

SUMMARY:

• Convergence insufficiency disorder can interfere with the ability to read, learn, and work at near (close distances).
• Patients should be made aware that convergence insufficiency is a fairly common condition and that treatment is very effective.²
• Treatments range from passive (prism lenses) to active (office-based vision therapy/orthoptics).^1-4
• According to a recent survey, home-based pencil pushups therapy (PPT) is the most commonly prescribed treatment⁵, but studies show that compliance (patient cooperation) is poor and that this treatment does not eliminate symptoms.^{3, 6}
• Eye surgery is rarely recommended.^{1, 2}
• The basic eye exam by a pediatrician is not adequate for the detection of convergence insufficiency (as well as other visual conditions).¹
• A person can pass the 20/20 eye chart test and still have convergence insufficiency.
• Convergence Insufficiency can be treated at any age.^{1, 2, 4}

FREQUENTLY ASKED QUESTIONS:

What is Convergence Insufficiency?

What are the Symptoms of Convergence Insufficiency?

How Common is Convergence Insufficiency?

Detection and Diagnosis of Convergence Insufficiency

Treatment of Convergence Insufficiency

Scientific Study of Convergence Insufficiency - Research Subjects Needed

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What is Convergence Insufficiency?
An eye muscle disorder in which the eyes do not look at near easily. An eye teaming problem in which the eyes have a strong tendency to drift outward when reading or doing close work (exophoria at near). If the eyes do drift out, the person is likely to have double vision.

To prevent double vision, the individual exerts extra effort to make the eyes turn back in (converge). This extra effort can lead to a number of frustrating symptoms which interfere with the ability to read and work comfortably at near.

What are the Symptoms of Convergence Insufficiency?
People who have convergence insufficiency may show and/or complain of the following while doing close work (i.e., reading, computer work, deskwork, playing handheld video games, doing crafts, etc.):

• eyestrain (especially with or after reading)
• headaches
• inability to concentrate
• short attention span
• frequent loss of place
• squinting, rubbing, closing or covering an eye
• blurred vision
• sleepiness (especially while reading)
• trouble remembering what was read
• words move, jump, swim or appear to float on the page
• problems with motion sickness and/or vertigo
• double vision

It is not unusual for people with convergence insufficiency to cover or close one eye while reading to relieve the blurring or double vision. Symptoms will be worsened by illness, lack of sleep, anxiety, and/or prolonged close work.

Many people who would test as having convergence insufficiency (if tested) may not complain of double vision or the other symptoms listed above because vision in one eye has shut down. In other words, even though both eyes are open, healthy and capable of sight, the person's brain ignores one eye to avoid double vision. This is a neurologically active process called suppression.¹

Suppression of vision in one eye causes loss of binocular (two-eyed) vision and depth perception. Poor binocular vision can have a negative impact on many areas of life, such as coordination, sports, judgment of distances, eye contact, motion sickness, etc. Consequently, a person with convergence insufficiency who is suppressing one eye can show some of the following symptoms:

• trouble catching balls and other objects thrown through the air
• avoidance of tasks that require depth perception (games involving smaller balls, handicrafts, hand eye coordination, etc.)
• frequent mishaps due to misjudgment of distances (particularly within twenty feet), such as:
  • trips and stumbles on uneven surfaces, stairs, and curbs, etc.
  • frequent spilling or knocking over of objects
  • bumping into doors and other objects
  • sports and/or car parking accidents
• avoidance of eye contact
• poor posture
• one shoulder noticably higher
• frequent head tilt
• problems with motion sickness and/or vertigo

If untreated, in some cases, convergence insufficiency can lead to an outward eye turn that comes and goes (intermittent exotropia).^{1, 2}

How Common is Convergence Insuffiiciency?
Convergence insufficiency has a reported prevalence among children and adults in the United States of 2.5 to 13%.^{1-3, 7}

Detection and Diagnosis of Convergence Insufficiency
An eye exam by a pediatrician or the 20/20 eye chart screening is not adequate for the detection of convergence insufficiency (and many other visual conditions). The most important diagnostic tools are convergence tests, not the 20/20 letter charts typically used by schools, pediatricians and eye doctors. A person can pass the 20/20 eye chart test and still have convergence insufficiency. A comprehensive vision evaluation by an optometrist is recommended for all individuals who do reading and deskwork -- particularly students.¹

Many undiagnosed children and adults avoid reading and close work or use various strategies to combat symptoms (using a ruler or finger to read, taking frequent breaks, etc.). The typical patient who seeks diagnosis is a teenager or young adult, complaining of gradually worsening eyestrain, headache, and blurred vision after brief periods of reading, and, sometimes, double vision with near work.² Convergence Insufficiency can be diagnosed and treated at any age.

Treatment of Convergence Insufficiency
Treatments for CI can be categorized as active or passive:

• Active treatment: The best treatment for convergence insufficiency is vision therapy which re-establishes the reflexes of convergence. Treatment usually consists of both in-office and home exercises. Children can respond quickly to vision therapy.^{1, 3}
• Passive treatment: Prismatic (prism) glasses can be prescribed to decrease some of the symptoms. Although prisms are effective, they are not as effective as vision therapy and may result in adaptation problems so that more prism is necessary in the future. Every optometric and ophthalmological textbook agrees that the primary treatment of convergence insufficiency should be vision therapy.¹

Pencil Push-ups: While a 2002 survey of ophthalmologists and optometrists indicated that home-based pencil-pushups therapy is the most common treatment, there is lack of evidence to support this method. The only scientific study done on pencil pushups showed it to be ineffective in eliminating symptoms.^{3, 6}

Surgical Care: The decision to proceed with eye muscle surgery should be made with caution and only after all other efforts have failed.^{1, 2}

According to Dr. M. Bartiss, O.D., M.D., "Patients typically present as teenagers or in early adulthood, complaining of gradually worsening eyestrain, periocular headache, blurred vision after brief periods of reading, and, sometimes, crossed diplopia with near work. It is not unusual for the patient to squint one eye while reading to relieve blurring or diplopia. Few, if any, symptoms are present at distance fixation. Symptoms are aggravated by illness, lack of sleep, anxiety, and prolonged near work. Untreated, the exophoria at near may break down to a poorly controlled intermittent exotropia. Fortunately, in most cases, convergence insufficiency is very amenable to orthoptics and vision therapy." 2

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References:

1. Cooper, J, Cooper, R. Conditions Associated with Strabismus: Convergence Insufficiency. Optometrists Network, All About Strabismus. 2001-2005.
2. Bartiss, M. Extraocular Muscles: Convergence Insufficiency. eMedicine.com, Inc., eMedicine Specialties, Ophthalmology. 2005.
3. Scheiman M, Mitchell GL, Cotter S, et al; the Convergence Insufficiency Treatment Trial (CITT) Study Group. A randomized clinical trial of treatments for convergence insufficiency in children. Archives of Ophthalmology. 2005;123:14-24. Complete article - PDF version
4. Birnbaum MH, Soden R, Cohen AH. Efficacy of vision therapy for convergence insufficiency in an adult male population. J Am Optom Assoc. 1999;70:225-232.
5. Scheiman M, Cooper J, Mitchell GL, et al. A survey of treatment modalities for convergence insufficiency. Optom Vis Sci. 2002;79:151-157.
6. Gallaway M, Scheiman M, Malhotra K. Effectiveness of pencil pushups treatment of convergence insufficiency: a pilot study. Optom Vis Sci. 2002;79:265-267.
7. Rouse MW, Borsting E, Hyman L, Hussein M, Cotter SA, Flynn M, Scheiman M, Gallaway M, De Land PN. Frequency of convergence insufficiency among fifth and sixth graders. Optom Vis Sci. 1999 Sep;76(9):643-9.