Abstract
Purpose :
Posterior Cortical Atrophy (PCA) is a neurodegenerative syndrome that is characterized by progressive degeneration of parietal and occipital lobe with associated cortical visual impairment, but whether there are changes in the retina in PCA was not known. The most common cause of PCA is Alzheimer`s disease (AD). Retinal nerve fibre layer (RNFL) atrophy, changes in retinal vessel calibres and an increase in drusen deposition has been associated with typical AD (tAD). In this study, we examined images of the retina of patients with PCA and compare these to tAD and healthy controls (HC).
Methods :
Ultra-wide-field colour and autofluorescence images (UWFI) and optical coherence tomography (OCT) scans were acquired of 33 PCA (MMSE<24), 28 tAD (MMSE<20) patients and 71 HC (MMSE>28) using OPTOS P200Tx scanning laser ophthalmoscope (SLO) and OPTOS OCT-SLO. Images with poor quality were removed from analysis. The study had full local Ethical Committee approval. UWFI were graded for absence/presence of pathological abnormalities. OCT scans were analysed for macular volume and thickness of retinal layers, whole retinal thickness as well as peripapillary vessel calibre (ppVC) using OPTOS OCT Viewer (v1.89) and OCTseg (v0.4) softwares. Statistical analysis was carried out using STATA and SPSS.
Results :
UWFI detected lower prevalence of reticular pseudodrusen in PCA (10%) than in tAD (30%) or HC (17%) [χ2=6.879, df=2, p=0.032]. There was a lower prevalence of far-peripheral hyper-fluorescence changes in tAD (24%) compared to PCA (44%) or HC (43%) [χ2=5.736, df=2, p=0.057]. More tortuous retinal vasculature was observed in tAD (45%) compared to PCA (22%) or HC (18%) [χ2=15.545, df=2, p<0.001]. Analysis of OCT scans showed a significant reduction in peripapillary outer plexiform-inner nuclear layer thickness in patients with PCA compared to HC (64.15µm±7.45µm vs 68.7µm ±9.45µm, p=0.049) and a significant increase in total ppVC in both PCA (457.05µm ±89.85µm) and tAD (478.4µm±83.4) compared to HC (411.15µm ±82.75µm) (p<0.05).
Conclusions :
Analysis of retinal images highlighted that there are ocular manifestations of both PCA and tAD suggesting that there might be additional value in detailed grading of retinal imaging in dementia.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.