Purpose.: To evaluate differences between the retinal nerve fiber layer (RNFL) thickness and RNFL+ ganglion cell layer (GCL) thickness in patients affected by Alzheimer's disease (AD) and healthy patients using spectral-domain optical coherence tomography (SD-OCT).

Methods.: This was a case-control prospective study. Twenty-one AD patients and 21 healthy subjects underwent neurological examination, clock-drawing test (CDT), Mini Mental State Examination (MMSE), and comprehensive ophthalmic evaluation with visual acuity. SD-OCT examination was performed using Spectralis and RTVue-100. An RNFL thickness map was obtained using the Spectralis volume protocol with 19 lines on the 30 field centered on the macula. On each B-scan, the outer RNFL limit was manually set. Statistical analysis was performed to assess interoperator RNFL evaluation thickness. An RNFL+ GCL thickness map was obtained using the RTVue-100 MM6 protocol. Maps were divided into the nine ETDRS subfields and each map value in every area was evaluated. A single eye from each patient was randomly chosen to perform the analysis. Differences between AD and healthy subjects were assessed.

Results.: The two study groups were age and sex matched. MMSE results were 19.9±3.1 and 27.9±1.3, respectively (P< 0.001). There was good agreement in the manual delimitation of the RNFL layer. There was a significant difference in the thickness of both the RNFL and the RNFL+ GCL in all examined fields. For example, in the inferior internal subfield, the RNFL thickness was 28.1±3.1 μm for AD patients and 32.6±3.8 μm for healthy subjects (P< 0.001).

Conclusions.: These results indicate that RNFL and RNFL+ GCL thickness measurements are reduced in AD patients compared with healthy subjects. This finding may represent a useful element for the diagnosis and follow-up of this pathology.