Alzheimer disease is hard, long and expensive to diagnose. In order to help the clinician, a new biomarker in Alzheimer disease seems to be very useful. The retina, as a window of the brain, could offer a new way to diagnose this common disease. Indeed, a retinal atrophy could especially appear in Alzheimer disease. Besides, many aspects about retinal alteration, visual function and their link with the disease deserve to be more explored. So as to fill these gaps, a new study about retinal specificity in Alzheimer disease appears to be relevant.

Inclusion Criteria:

• Patients having a consultation in the Research and Resources Memory Center of Amiens (RRMC) ,
• patients registered in the Alzheimer National Bank and having an Alzheimer Disease based on NIA-AA (McKahnn2011)and IWG2 (Dubois et al, 2014) criteria or, having a Lewy body disease based on revised criteria of McKeith et al 2020
• patients having a complete neuropsychological evaluation including a visual inspection time.
• patients having a MMSE ≥ 18/30 so as to ensure a good homogeneity of the group and to have an adequate ocular exam's quality.
• patients having an available MRI in the CHU's database including a 3DT1 sequence
• patients having a visual acuity better than 5/10, spherical refraction of +/- 5D, an astigmatism < 3D and an applanation IOP <22mmHg

Exclusion Criteria:

• Any other neurocognitive disorder
• Any other optical neuropathy including glaucoma
• All kind of retinal disease (diabetic retinopathy, age-related macular degeneration…)
• Diabetes mellitus
• Uncontrolled hypertension blood pressure
• Any ophthalmological conditions interfering with a good ocular examination or OCT quality (cataract, corneal opacity..)
• Severe dementia preventing a good ophthalmological examination
• Not consenting patient
• Patient with guardianship or curatorship having symptoms preventing a good ophthalmological examination (agitation, unstable ocular fixation)