Abstract
Purpose :
We used high resolution spectral-domain optical coherence tomography (SD-OCT) to determine the thickness changes of the retinal Ganglion Cell Complex (GCC) in Alzheimer's disease patients compared with matched controls.
Methods :
We enrolled 60 subjects, 30 Alzheimer disease (AD) patients (mean age 64,19 +/- 7,5 years, best corrected visual acuity >8/10 without glaucoma or other comorbidities affecting the Ganglion Cell Layer (GCL) thickness. They were compared to 30 matched controls in terms of age, sex and refractive error/axial length. The important point of our study is that AD patients were selected by biological confirmation (CSF biomarkers for AD).The SD-OCT images were captured using macular cube (512x128) and ONH Cube 200x200 protocols with Cirrus and Heidelberg optical coherence tomographs. Retinal layer segmentation was performed using algorithms established for glaucoma studies. Thickness of the GCL + inner plexiform layer (IPL), RNFL, outer plexiform/inner nuclear layers (OPL+INL), and outer nuclear/photoreceptor layers (ONL+PRL) were mesured and compared in AD versus control eyes.
Results :
In early (less than 24 months from diagnosis) AD eyes, there was a significant (p<0,05) reduction in supero-temporal quadrant GCL +IPL thickness compared with the values observed in control eyes. No correlations (p>0,05) were found in the other quadrants and in the Ganglion Cell Complex (GCC) mean thickness. In advanced AD, there was a significant (p<0,05) reduction in thickness in all quadrants comparing to controls. There was a direct correlation between GCC thickness and MMSE score and an indirect correlation between GCC thickness and tau and tau phospholirated protein.
Conclusions :
Our results suggest that in early AD patients, there is a reduction of supero-temporal quadrant GCC thickness evaluated in vivo by OCT and we could use this measure as a biomarker of AD in preclinical states, further studies are needed to confirm these preliminary results.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.