Objective Assessment of Disparity Vergence After Treatment of Symptomatic CI in Children

Objective Assessment of Disparity Vergence After Treatment of Symptomatic Convergence Insufficiency (CI) in Children

This study is designed to evaluate changes in objective measures of disparity vergence after office-based vergence/accommodative therapy (OBVAT) for convergence insufficiency (CI) in children 12-17 years old.

30 participants with normal binocular vision and 30 with CI will be recruited for this prospective study. All participants with CI will be treated with 12 weeks of office-based vergence/accommodative therapy. The primary outcome measure will be the average peak velocity for 4° symmetrical convergence steps. Other objective outcome measures of disparity vergence will be time to peak velocity, latency, and accuracy. Changes in clinical measures [near point of convergence (NPC), positive fusional vergence at near (PFV)] and symptoms will be evaluated.

Inclusion Criteria:

• CI Symptom Survey score ≥ 16
• Exophoria at near at least 4 greater than at far
• Receded near point of convergence (NPC) of 6 cm break
• Insufficient positive fusional vergence (PFV) at near (i.e., failing Sheard's criterion or PFV ≤15 base-out break)
• Best-corrected distance visual acuity of 20/25 or better in each eye
• Random dot stereopsis appreciation of 500 seconds of arc or better
• Wearing appropriate refractive correction (spectacles of contact lenses) for at least 2 weeks prior to final determination of eligibility for any of the following uncorrected refractive errors (based on cycloplegic refraction within prior 12 months)
• No use of BI prism or plus add at near for 2 weeks prior to study and for duration of study

Exclusion Criteria:

• Constant strabismus at distance or near
• Esophoria of ≥ 2∆ at distance
• Vertical heterophoria ≥ 2∆ at distance or near
• ≥ 2 line interocular difference in best-corrected visual acuity
• Near point of accommodation >20 cm in either eye as measured by push-up method
• Manifest or latent nystagmus
• History of strabismus surgery or refractive surgery
• CI associated with head trauma or known disease of the brain
• Diseases known to affect accommodation, vergence, or ocular motility
• Inability to comprehend and/or perform any study-related test