Prevalence of Convergence Insufficiency in Parkinson's Disease.

Background: We recently reported that convergence insufficiency (CI)-type visual symptomatology was more prevalent in participants with Parkinson's disease (PD), compared to controls. The objective of this work was to determine the prevalence of a confirmed clinical diagnosis of CI in PD, compared to controls.

Methods: Participants with (n = 80) and without (n = 80) PD were recruited and received an eye exam. Published criteria were used to arrive at a clinical diagnosis of CI. The Convergence Insufficiency Symptom Survey (CISS-15) questionnaire was administered to each participant, with a score of ≥21 being considered positive for CI symptomatology. Student test, chi-square, or nonparametric tests at the 0.05 level were used for statistical significance.

Results: A total of 43.8% of participants with versus 16.3% without PD had a clinical diagnosis of CI ( 0.001). A total of 53.8% of participants with versus 18.8% without PD had scores on the CISS-15 of ≥21 ( 0.001).

Conclusions: These results indicate that individuals with PD have a higher prevalence of CI and CI symptomatology than controls. These data provide evidence supporting the notion that treatment for symptomatic CI should be investigated in individuals with PD.