OBJECTIVE: Parkinson's disease is the second most common disease of the central nervous system after Alzheimer's disease. Currently, no blood test or other laboratory tests are available to diagnose this condition. One of the practical methods in diagnosing and evaluating the progress of neurodegenerative diseases is the use of optical coherence tomography (OCT), with which it is possible to accurately measure the thickness of the layers of the retina, as well as the thickness and volume of the macula. The goal of this study was to determine the OCT findings in patients with Parkinson's disease compared to the normal population. METHOD: This study was conducted in 2019 at the Neurology Clinic of Farshchian Hospital, Hamadan (Iran). Sampling was performed based on the inclusion/exclusion criteria of the study and the required sample size. Patients referred to the Neurology Department of Farshchian Hospital were first examined by a neurologist, then referred to the ophthalmology clinic for a complete ophthalmological examination. OCT imaging was performed by an experienced, skilled optometrist after pupillary dilation with tropicamide drops. RNFL thickness, macula and fovea, and the measured macular volumes were recorded along with other information, including age, sex, disease duration, severity of disease symptoms, and drug use. Finally, the data were analyzed using SPSS version 22 statistical software. FINDINGS: A total of 103 individuals including 49 males (47.6%) and 54 females (52.4%) with a mean age of 70.66 years were examined. The subjects included two groups, patients (53 subjects) and control (50 subjects), who were matched in terms of age and gender distribution. The mean RNFL thickness and macular thickness and volume in the patient group were significantly lower than in the control group (P<
0.05). There was an inverse relationship between the thickness of the RNFL and the macula with the duration of the disease and the severity of the disease symptoms (P<
0.05). CONCLUSION: In this study, a significant decrease in RNFL thickness and macular thickness and volume was shown in patients with Parkinson's disease compared to the age- and sex-matched control group. It can be said that the changes in the macula and RNFL in Parkinson's disease and with progression of the disease are suitable markers for diagnosing and investigating the progression of Parkinson's disease.