Convergence Insufficiency Neuro-Mechanism Adult Population Study: Phoria Adaptation Results

Area of Science:

• Ophthalmology
• Vision Science
• Neuroscience

Background:

• Phoria adaptation, a measure of binocular vision flexibility, differs between individuals with normal binocular vision and those with symptomatic convergence insufficiency (CI).
• Understanding these differences is crucial for developing effective treatments for CI.

Purpose of the Study:

• To compare changes in phoria adaptation between young adult binocularly normal controls (BNCs) and participants with symptomatic CI.
• To evaluate the efficacy of office-based vergence accommodative therapy (OBVAT) versus office-based placebo therapy (OBPT) in improving phoria adaptation in CI patients.

Main Methods:

• A double-masked randomized clinical trial involving 50 BNC and 50 CI participants.
• Participants received 12 one-hour office sessions of either OBVAT or OBPT with home reinforcement.
• Phoria adaptation (rate and magnitude) was measured at near (40 cm) using the flashed Maddox rod technique at baseline and outcome.

Main Results:

• Significant differences in baseline phoria adaptation rates and magnitudes were observed between BNC and CI participants (P < 0.001).
• OBVAT significantly improved both the magnitude and rate of phoria adaptation for base-in and base-out conditions in the CI group compared to baseline (P < 0.01).
• No significant improvements in phoria adaptation were observed in the CI group receiving OBPT.

Conclusions:

• Phoria adaptation is demonstrably different between individuals with normal binocular vision and those with symptomatic CI.
• OBVAT is an effective therapeutic intervention that significantly enhances the rate and magnitude of near phoria adaptation in CI patients.
• These findings support the clinical utility of OBVAT for treating symptomatic convergence insufficiency.