Conjunctival impression cytology and tear film analysis in early-stage Parkinson's disease

Purpose: We aimed to evaluate conjunctival impression cytology (CIC) findings, tear parameters, and ocular surface in early-stage Parkinson's patients and compare the results with the control group. Methods: This cross-sectional comparative study included 49 early-stage Parkinson's Disease (PD) patients and 45 healthy individuals as a control group. Clinical staging of Parkinson's patients was performed according to the Hoehn-Yahr Scale. Those with stages 1 and 2 were defined as early-stage PD. Ocular surface disease index (OSDI) questionnaire, tear breakup time (TBUT), Schirmer test, and CIC were applied to the patient and control groups. Results: There was no significant difference between the two groups in terms of mean age and gender (p = 0.606, p = 0.357, respectively). Schirmer test and TBUT results in the PD group were significantly lower compared to the control group (p < 0.001, p < 0.001). Meanwhile, the OSDI score and CIC stage of the PD group were significantly higher than that of the control group (p < 0.001, p < 0.001). Conclusions: In early-stage PD, decreased TBUT and Schirmer test values, conjunctival goblet cell loss, and squamous metaplasia development indicate that the ocular surface is affected. Early diagnosis of dry eye in Parkinson's patients is important for preventing complications such as ocular surface damage and visual disturbances.