Acquired colour deficiency in patients with Parkinson's disease

The blue cone pathway is reported to be affected early in Parkinson's disease (PD) and acquired type three (tritan) defects may occur. Sixty-one patients attending a treatment and rehabilitation centre for PD were examined with clinical colour vision tests. Seven of 13 patients, for whom the diagnosis of PD was equivocal or who had other medical conditions, were identified as having tritan colour deficiency. Results for the remaining 44 PD patients were compared with 40 age matched controls. Ten PD patients (22.7%) had tritan defects. Tritan defects were not found in the control group but performance on some tests was age related. We conclude that clinical tests for tritan colour deficiency are unlikely to be helpful in identifying PD.