Randomized Trial of Treatments for Convergence Insufficiency

Considerable controversy exists regarding the best treatment for convergence insufficiency (CI), a common condition that often interferes with the ability to perform near work. The two most widely used treatments have significant differences in costs and in practitioner perceived utility. Pencil push-up therapy (PPT) is a simple, low-cost treatment in which patients are prescribed a single procedure to perform at home with only periodic follow-up. Office-based vision therapy (OBVT) is a more comprehensive, time-consuming, complex, and costly treatment in which patients are scheduled for weekly in-office therapy visits and are often prescribed a specific sequence of therapeutic procedures to perform at home. It is important to consider whether either, neither, or both treatments are effective.

The Convergence Insufficiency Treatment Trial (CITT) is a prospective, masked-examiner, multi-center clinical trial in which patients are randomized to one of these two treatment approaches. The primary goal is to answer the following question:

After 12 weeks of treatment, is one therapy more effective than the other in improving CI signs and symptoms? We will test the null hypothesis that there is no difference in the distribution of outcomes between the two populations.

The primary outcome measure will be a classification of each patient as a "success," "improvement," or "failure." This classification will be based on the level of improvement in both the signs (near point of convergence and positive fusional vergence) and symptoms of CI.

Additional questions relate to longer term effects:

• Are the patients who were classified as "success" or "improvement" at twelve weeks the same at the one-year follow-up for each treatment group?
• Are there differences in the distributions of changes in near point of convergence, positive fusional vergence, or accommodative amplitudes, between the two treatment groups, at twelve weeks and at one-year of follow up?

Inclusion criteria

• Age 9-30 years
• Best corrected visual acuity of 20/25 in both eyes at distance and near
• Willingness to wear eyeglasses or contact lenses to correct refractive error, if necessary
• Exophoria at near at least 4 prism diopters greater than at far
• Insufficient positive fusional convergence (i.e., failing Sheard's criterion or minimum normative positive fusional vergence (PFV) of 15 base-out break).
• Receded near point of convergence of > 6 cm break.
• Normal random dot stereopsis using a 500 seconds of arc target.
• CI Symptom Survey score > 16 for subjects in 9-18 year age range and > 21 for subjects in the 19-30 year age range.
• Informed consent and willingness to participate in the study and be randomized

Exclusion criteria

• CI previously treated with pencil push-ups (no more than 2 months of treatment within the past year)
• CI previously treated with office-based vision therapy/orthoptics (no more than 2 months of treatment within the past year)
• Amblyopia
• Constant strabismus
• History of strabismus surgery
• Anisometropia >1.50D difference between eyes
• Prior refractive surgery
• Vertical heterophoria greater than 1 
• Systemic diseases known to affect accommodation, vergence, and ocular motility such as: multiple sclerosis, Graves's thyroid disease, myasthenia gravis, diabetes, and Parkinson disease
• Any ocular or systemic medication known to affect accommodation or vergence
• Monocular accommodative amplitude less than 4 D in either eye as measured by the Donder's push-up method
• Manifest or latent nystagmus
• Attention deficit hyperactivity disorder (ADHD) or learning disability diagnosis by parental report
• Household member or sibling already enrolled in the CITT
• Any eye care professional, technician, medical student, or optometry student