The effect of levodopa and dopamine agonists on optic nerve head in Parkinson disease

PURPOSE. To evaluate the effects of levodopa and dopamine agonists on retinal nerve fiber layer using scanning laser ophthalmoscope. METHODS. Forty-four patients with the diagnosis of Parkinson disease and receiving levodopa or dopamine agonist monotherapy were included in this prospective study. The control group consisted of 21 normal cases. The optic nerve head images were taken with Heidelberg Retina Tomograph; rim area, rim volume, mean retinal nerve fiber layer thickness, and the results of Moorfields regression analysis were calculated. The measurement results were evaluated with Kruskal Wallis test and Mann-Whitney U-test. RESULTS. There was no significant difference in mean age among groups (p=0.093). Retinal nerve fiber layer was measured to be significantly decreased in cases with Parkinson disease (p=0.004) while rim area and rim volume did not show a significant change (p=0.224, p=0.804 respectively). Rim area, rim volume, and retinal nerve fiber layer were significantly greater in the group treated with levodopa while it was the thinnest in the group receiving dopamine agonists. CONCLUSIONS. Levodopa can have a protective affect to retinal nerve fiber layer in Parkinson disease compared to dopamine agonists.