The study was performed to analyse the retina of patients with Parkinson's disease (PD) for morphological changes compared to healthy controls (HC) using spectral-domain optical coherence tomography (SD-OCT) and confocal scanning laser ophthalmoscopy. Methods
We enrolled 108 patients with idiopathic PD and 165 HC. All study participants underwent an ophthalmological examination to exclude ophthalmological disorder potentially interfering with the retinal analyses. Peripapillary retinal nerve fibre layer (RNFL) thickness and macular thickness and volume were measured by a SD-OCT device (Heidelberg Spectralis®). Stereometric parameters of the optic disc were acquired by Heidelberg Retina Tomograph (HRT III). Results
The RNFL thickness did not significantly differ between patients with PD and HC. The thickness of the central minimum and the centre of the macular area were significantly reduced in patients with PD, while the total macular volume did not significantly differ between the groups. Furthermore, we noted an inverse correlation between the central minimum thickness and the disease severity (assessed by the Hoehn and Yahr scale). HRT data showed no significant differences. Conclusion
The HRT device and the RNFL measurements of the SD-OCT did not prove to be a clinically valid diagnostic tool to distinguish eyes of patients with PD and HC. However, the macular region and especially the foveola (central minimum) with the highest density of photoreceptor cells seem to be more sensitive and might be potential biomarkers.