Retinal Changes in Parkinson's Disease: A Longitudinal Follow-up Study

There is definite evidence for the involvement of retina in Parkinson's disease (PD). However, a specific pattern has not been clear due to the cross-sectional nature of the majority of the previous studies.

The aim of this work was to study the pattern of changes in the retinal layers in patients with PD on longitudinal follow-up.

Twelve patients with PD (23 eyes) were evaluated at baseline with complete history, clinical examination, Unified Parkinson's Disease Rating Scale (UPDRS) motor part, visual acuity, and retinal imaging with spectral-domain Optical Coherence Tomography. After a mean duration of 3.7 ± 0.46 years, patients were re-evaluated.

The Central Macular Thickness (CMT) of the right eye was found to be significantly thicker during the follow-up (P = 0.002). The outer retinal layer in the temporal quadrant at 0.5 centimeters from the fovea of the left eye was found to be significantly thinner (P = 0.001).

The serial evaluation of the retinal layers in patients with PD suggests a progressive loss of thickness of the outer retinal layer. The involvement of non-dopaminergic mechanisms, especially glutamatergic pathways, may be responsible for these changes.