A Randomized Controlled Study Using Non-invasive Brain Stimulation to Facilitate the Effectiveness of Vergence/Accommodative Therapy in Symptomatic Convergence Insufficiency

Summary

The goal of this randomized controlled trial is to test the effectiveness of non-invasive brain stimulation in treating adults with symptomatic convergence insufficiency compared to vergence/accommodative therapy. The main questions it aims to answer are: 1. Can non-invasive brain stimulation shorten the treatment time of office-based vergence/accommodative therapy for convergence insufficiency? 2. Is non-invasive brain stimulation alone just as effective as office-based vergence/accommodative therapy in treating convergence insufficiency? The investigators hypothesize that non-invasive brain stimulation will shorten the treatment time from 12 weeks to 8 weeks of office-based vergence/accommodative therapy and that non-invasive brain stimulation alone would be equally effective as office-based vergence/accommodative therapy in improving symptomatic convergence insufficiency. Participants will be randomized into one of three treatment groups: 1. Non-invasive brain stimulation with office-based vergence/accommodative therapy. 2. Sham stimulation with office-based vergence/accommodative therapy. 3. Non-invasive brain stimulation only. Researchers will compare baseline measurements of near point of convergence (NPC) and positive fusional vergence (PFV) to post-treatment measurements for each group.

Eligibility

Age range

18–40 years

Sex

All

Healthy volunteers

Yes

Interventions

• Device
  Anodal-Transcranial Direct Current Stimulation

  Non-invasive brain stimulation will involve the use of anodal transcranial direct current stimulation to apply a 2 milliamp current over the left frontal eye field for approximately 20 minutes with a ramp up to the maximum programmed current and ramp down of 20 seconds.

• Behavioral
  Office-Based Vergence/Accommodative Therapy

  Office-based vergence accommodative therapy involves weekly in-office appointments with the therapist lasting approximately 60 minutes per visit during which time in-office procedures will be performed, and home therapy procedures will be demonstrated. Participants will be prescribed 15 minutes of home reinforcement therapy procedures to be completed 5 days per week. Therapy will consist of two phases adapted from the Convergence Insufficiency Treatment Trial (CITT). Therapy procedures will include gross convergence, accommodation. non-computer based vergence, and computer-based vergence.

• Device
  Sham Transcranial Direct Current Stimulation

  Sham transcranial direct current stimulation will be applied over the left frontal eye field with the current ramping up for 20 seconds before ramping down for 20 seconds. The 2 milliamp current stimulation will occur for only a few seconds at the start and at the end of the 20 minutes.

Location