Abstract
Purpose: :
To evaluate differences in Retinal Nerve Fibre Layer (RNFL) thickness and RFNL+ Ganglion Cells Layer (GCL) between patients affected by Alzheimer Disease (AD) and age-matched healthy patients
Methods: :
Exclusion criterion was the presence of any possible cause of RNFL and GCL thinning. Patients and controls underwent neurological examination, clock drawing test (CDT), Mini Mental State Examination (MMSE) and comprehensive ophthalmic evaluation. Spectral-Domain Optical Coherence Tomography (SD-OCT) examination was performed with Spectralis (Heidelberg Engineering), and RTVue-100 (Optovue Inc). RNFL thickness map was obtained with Spectralis volume protocol with 19 lines on 30° field centred on optic disk. On each B-scan the outer RNFL limit was manually set. RFNL+GCL thickness map was obtained with RTVue-100 MM6 protocol. Maps were divided in 9 zones (central, superior internal, temporal internal, inferior internal, nasal internal, superior external, temporal external, inferior external, nasal external) and each map value in every field was evaluated
Results: :
We analyzed 8 AD patients (16 eyes) with RTVue-100, 7 AD patients (14 eyes) with Spectralis and 8 normal subjects (15 eyes) with both the instruments. A significant difference between RNFL thickness in AD patients and controls was demonstrated in all the fields (ANOVA: p between 0.0001 and 0.033), except for the inferior internal field (p=0.137). RFNL+GCL thickness was different between the two groups in all the fields (ANOVA: p between 0.001 and 0.025), except in the central one (p=0.76)
Conclusions: :
RFNL and RFNL+GCL thickness measurements are reduced in AD, compared to healthy subjects. This finding may represent an integrative element for the diagnosis and follow up of this pathology. Further studies are necessary to assess the correlation between AD stage and RNFL thickness and to verify the reduction of RNFL thickness in the progression of the disease
Keywords: nerve fiber layer • ganglion cells • retina