|Title||The value of vergence facility testing for the diagnosis of convergence insufficiency|
|Author, Co-Author||Lynn Trieu, Sweta Das, Jenny Myung, Stanley Hatch, Mitchell Scheiman|
Purpose: To compare the effectiveness of vergence facility testing at near vs. distance as a diagnostic test in the assessment of symptomatic convergence insufficiency (CI).
Methods: To be eligible for the study subjects had to be between the ages of 9 to 30 years of age. In addition, the following clinical findings were required, 1) exophoria at near at least 4 Δ greater than at far, 2) insufficient positive fusional convergence (PFV) (i.e. failing Sheard’s criterion or positive fusional vergence ≤ 15 Δ base-out break), 3) receded near point of convergence (NPC) of ≥ 6 cm break, and 4) symptomatic based on the CI Symptom Survey (CISS). Vergence facility testing was performed three times at distance and near using 12ÂżBO and 3Âż BI and a vertical column of 20/30 letters as a target at 6M and 40cm respectively. The mean cycles per minute (cpm) of the three measurements was used for data analysis.
Results: Twenty-six subjects were recruited with a mean age of 13.1 years. The distance at which vergence facility was performed had a significant effect on the outcome, M = 5.4 cpm, 95% confidence interval [3.66, 7.13] at distance vs. M = 9.0 cpm, 95% confidence interval [5.35, 12.60] at near, p < 0.001. Using currently accepted clinical norms, 26.9% of the subjects would have passed vergence facility at near, but would have failed vergence facility testing at distance. In addition, 26.9% of the subjects were unable to complete even one cpm at distance compared to 3.8% at near.
Conclusion: Symptomatic convergence insufficiency patients have greater difficulty performing vergence facility at distance compared to vergence facility at near. The results suggest that vergence facility testing at distance may be a more sensitive method for the assessment of vergence facility in subjects with a suspected diagnosis of CI.
|Affiliation of Co-Authors||Pennsylvania College of Optometry at Salus University, Pennsylvania College of Optometry at Salus University, Pennsylvania College of Optometry at Salus University, Pennsylvania College of Optometry at Salus University|