Retinal nerve changes in patients with tremor dominant and akinetic rigid Parkinson's disease.

Parkinson disease is a multisystem neurodegenerative disease which involves not only basal ganglia and extrapyramidal system but also many other neurologic systems such as retinal ganglion cells. Optical coherence tomography (OCT) is a non-invasive method for assessment of retinal nerve fiber layer (RNFL) thickness and its changes in different diseases. To evaluate the RNFL thickness in patients with Parkinson disease (PD), we performed OCT in patients with PD and compared it with a control group. From October 2010 to July 2011, 27 PD patients (54 eyes) and 25 healthy persons (50 eyes) were entered to this analytical cross-sectional study according to the defined criteria. PD patients were categorized into two groups "akinetic rigid (AR) and tremor dominant (TD)". RNFL was divided into four quadrants and was assessed by OCT. Afterwards; the data were analyzed by bivariate and multivariate models. The RNFL thickness in PD was significantly lower than the control group. Also, the thicknesses of inferior and nasal quadrants of RNFL in TD group were significantly more than AR group. According to these findings, OCT can be used as a sensitive and objective marker for assessment of early neurodegenerative changes of PD and early initiation of neuroprotective treatments. Future studies with adequate sample sizes are recommended to investigate interactions between age, distribution of the disease and type of PD as well as the effects of individual factors.