Implementing potential biomarkers for early detection of retinal changes in Parkinson's disease: Preliminary study on BDNF role

BackgroundVisual dysfunctions in Parkinson's disease (PD) patients suggest a possible degeneration of dopaminergic retinal layers, This study aimed to investigate macular retinal thickness in PD patients versus healthy controls using Optical Coherence Tomography (OCT), a non-invasive technique for in vivo retinal imaging. The role of the Val66Met polymorphism in the BDNF gene in relation to retinal degeneration and clinical features of PD was also explored.MethodsThis case-control study included 26 patients with idiopathic PD and 78 age- and sex-matched healthy controls, for a total of 208 eyes. All subjects underwent a 512 × 496-line OCT volumetric scan centred on the macular region.ResultsMacular thickness was measured in each sector and as an average across 360°. Significant differences were found in the superior sector of the left eye (OS2) (increase of 3 units in PD), the inferior sector of the left eye (OS2) (decrease of 3 units in PD), and the total volume of both eyes (decrease of 0.13 units in PD). An inverse correlation between retinal thickness and age at onset was observed in the temporal and inferior sectors of both eyes. The Val/Met heterozygous polymorphism was identified in 30.7% of PD patients.ConclusionsThe study confirms that thinning of the inner retinal layers is associated with PD. OCT provides a rapid, non-invasive, repeatable, and cost-effective method for in vivo assessment of retinal layers, supporting its potential as an early biomarker for PD. Further longitudinal studies with larger samples are needed to clarify the role of the BDNF polymorphism in retinal degeneration in PD.