Parkinson's Disease and Diplopia

Objective: To describe the spectrum of ocular dysconjugacy in Parkinson's disease (PD). Methods: Forty-four consecutive PD patients with diplopia (and 9 PD controls without diplopia) were examined for ocular dysconjugacy, including convergence insufficiency (CI). Results: Forty-two PD patients had CI with or without diplopia (2 could not be tested), and 15/44 PD patients also had distance diplopia (hypertropia-9, exotropia-4, variable horizontal heterotropia-1, esotropia-1) of diverse etiologies. All (9/9) control patients had CI. These patients of similar age without diplopia and with shorter duration of PD (P = 0.05) had CI with significantly greater (p < 0.0001) convergence fusional amplitudes than PD patients with diplopia. Conclusions: Prior studies underestimate the frequency of CI in PD patients with visual complaints. In this series 100% of tested patients with diplopia had CI. Comparison of PD patients with and without diplopia demonstrates that convergence fusional amplitudes decrease as disease duration increases. CI is a common accompaniment of PD, the most frequent cause of diplopia, and may reflect extranigral pathology.