Tear film tests in Parkinson's disease patients.

OBJECTIVE

Parkinson's disease (PD) has both motor and nonmotor features. Parkinson's disease patients are prone to dry eye due to both autonomic dysfunction and motor symptoms affecting blinking. This study was conducted to investigate the changes in tear functions in PD patients.

DESIGN

Nonrandomized, prospective, clinical study.

PARTICIPANTS

Fifty-six eyes of 56 consecutive patients with PD were studied. Thirty-six eyes of age-matched non-PD patients without pathology affecting tear tests were examined as control subjects.

INTERVENTION

Modified Hoehn-Yahr (H-Y) scale, blink rate (BR), and tear tests were examined.

MAIN OUTCOME MEASURES

Modified H-Y scale, BR, dry eye assessment questionnaire, meibomian gland evaluation, tear meniscus height, tear breakup time, fluorescein stain, rose bengal stain, Schirmer's test, and phenol red thread test.

RESULTS

Overall tear function abnormalities were significantly more common in PD patients (P = 0.001, Mann-Whitney U test). Each test was found to be significantly disturbed in PD patients relative to controls (P<0.05, Mann-Whitney U test). Each PD patient had at least 1 abnormal test. Overall tear function abnormalities as assessed by the total abnormal test count correlated with the H-Y score (P<0.001, Spearman rho correlation). Parkinson's disease patients' mean BR (12.7+/-7.42 per minute) was significantly less than the controls' (21.8+/-7.37) (P<0.01, Student's t test). The abnormality in each tear test, except those for meibomian gland function and tear meniscus height, was significantly related to the H-Y scores (P<0.05, chi2 linear-by-linear association).

CONCLUSION

The results of this study indicate that PD is associated with disturbances in tear function. With the exception of meibomian gland disease and tear meniscus height, the tests were found to have a linear association with the H-Y scale, which may be attributed to associated dysfunctions of PD.