Abstract
BACKGROUND: To evaluate static and dynamic pupillary functions, contrast sensitivity, and retinal nerve fiber layer (RNFL) thickness in patients with Parkinson's disease. METHODS: The study included 25 right eyes of patients with Parkinson's disease (mean age: 67.88 ± 9.40 years) and 26 right eyes of age- and sex-matched healthy controls (mean age: 64.15 ± 7.60 years). Following the measurement of visual acuity and intraocular pressure, the RNFL thickness of the right eye was assessed using optical coherence tomography (Optovue, Inc., Fremont, CA, USA), and contrast sensitivity was measured with the CSV-1000E (Vector Vision, Dayton, OH, USA). Following a 5-minute period of dark adaptation, both static and dynamic pupillographic parameters were assessed using the Sirius corneal topography device (Sirius, CSO, Florence, Italy). RESULTS: There was no statistically significant difference between the groups in terms of age and sex (p = 0.126 and p = 0.579, respectively). RNFL thickness in the superior, inferior, nasal, and temporal quadrants of the right eye were as follows for Parkinson's and control groups, respectively: 133.6 ± 18.03 vs. 144.73 ± 17.44 μm (p = 0.03), 122.0 ± 14.47 vs. 134.96 ± 25.28 μm (p = 0.031), 67.76 ± 12.05 vs. 74.65 ± 12.05 μm (p = 0.047), and 66.36 ± 8.72 vs. 72.77 ± 14.0 μm (p = 0.057). A statistically significant thinning was observed in all quadrants except the temporal quadrant in Parkinson's patients (Fig. 1). Contrast sensitivity was significantly lower in the Parkinson's group across all spatial frequencies compared to controls (p = 0.03, 0.01, < 0.01, and 0.02, respectively) (Fig. 2). Although pupil sizes were smaller in the Parkinson's group under scotopic, mesopic, and photopic conditions in static pupillography, the differences were not statistically significant (p > 0.05). Similarly, in dynamic pupillography, the pupil diameters at 0, 2, 4, 8, 12, and 16 s were smaller in the Parkinson's group, but no statistically significant differences were found between the groups (p > 0.05) (Fig. 3). CONCLUSIONS: While a significant reduction in RNFL thickness and contrast sensitivity was observed in patients with Parkinson's disease, static and dynamic pupillographic parameters did not differ significantly between the groups. Therefore, the prognostic utility of pupillography in Parkinson's disease remains inconclusive and should be further investigated in larger and longitudinal studies.