Distribution of retinal layer atrophy in patients with Parkinson disease and association with disease severity and duration.

PURPOSE To evaluate the thickness of the 10 retinal layers in the paramacular area of Parkinson disease patients using a new segmentation technology of optical coherence tomography (OCT) to examine whether the thickness of specific layers predicts neurodegeneration or Parkinson disease severity. DESIGN Observational prospective study. METHODS Parkinson disease patients (n = 129) and age-matched healthy subjects (n = 129) were enrolled. The Spectralis OCT system was used to automatically segment all retinal layers in a parafoveal scan using the new segmentation application prototype. Mean thickness of each layer was calculated and compared between Parkinson disease patients and healthy subjects, and between Parkinson disease patients with disease durations of less than or at least 10 years. A correlation analysis was performed to evaluate the association between retinal layer thickness, duration of disease, and Parkinson disease severity. Logistic regression analysis was performed to determine the most sensitive layer for predicting axonal atrophy. RESULTS Parkinson disease patients showed statistically significant reduced thickness in the retinal nerve fiber, ganglion cell, inner plexiform, and outer plexiform layers and increased thickness in the inner nuclear layer compared with healthy subjects (P < .05). The inner retinal layers were more affected in Parkinson disease patients with long disease duration. The ganglion cell layer thickness was inversely correlated with disease duration and Parkinson disease severity, and was predictive of axonal damage in Parkinson disease patients. CONCLUSIONS The segmentation application of the Spectralis OCT revealed retinal layer atrophy in Parkinson disease patients, especially in the inner layers of patients with long disease duration. Ganglion cell layer reduction was associated with increased axonal damage.