Abstract
Purpose :
Patients that suffer from Parkinson disease (PD) present visual dysfunctions as some of the first signs of the pathology. The aim of this study was to evaluate if there were histological changes in the retina and optic nerve in PD.
Methods :
Control and PD human donated eyes and optic nerves were available for this study. An optic nerve morphometric analysis was performed, cryosections were stained with hematoxylin in order to analyze the optic nerve size and the number of bundles, area and distribution. Ganglion cell density was assessed by immunohistochemistry and confocal microscopy in whole-mount retinas. The morphology, number and distribution of Iba1+ cells in optic nerve cryosections and retinal whole-mounts was analyzed in order to clarify microglial implication.
Results :
There is an increase of total nerve area (p<0.01) and number of bundles in PD optic nerves (p<0.05). Iba1+ cell morphology and location change in PD while the cell density is maintained. These cells present an amoeboid morphology instead of their typical ramified morphology. Besides, in control optic nerves they are only disposed around the bundles, but in PD there is an infiltration and they occupy all the bundle area. Finally, the number of ganglion cells in Parkinson retinas is reduced compared with controls (p<0.05), what can trigger the observed optic nerve changes.
Conclusions :
In this study we describe a ganglion cell degeneration and an optic nerve remodelling event with microglia implication in PD. This correlates with the ganglion cell layer thinning described in OCT and could help to explain the visual impairment reported in PD patients.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.