N = 10, who do not use contact lenses or eye glasses and have a recent evaluation of vision 10/10 ta participate in the repeatability study.

N = 30 (10 patients with thyroid associated orbitopathy (TAO), 10 patients with inflammatory optic neuropathy (ION), 10 patients with ischemic neuropathy), all chronic patients followed in ophthalmology consultation, enlightened volunteers ta participate in the study, and presenting a decrease in residual visual acuity entering the TAO, inflammatory or ischemic frameworks.

N = 30 (10 patients with TAO, 10 patients with ION, 10 patients with ischemic neuropathy) all patients seen in the acute phase in ophthalmology consultation who will accept participation in the study, knowing the constraint of repeating the examination in the chronic phase.

Patients will undergo through an MRI-scan using the ASL MRI sequence, as described per protocol.

implementing a protocol based on 2 imaging sessions : 1st session with 2 ASL sequences and a 2nd session scheduled 5-7 days later in similar conditions including 1 ASL in volunteers will be applied. This protocol allows assessing the intra-day and the inter-day variability of the measurements using Intra-Class Correlation Coefficient and metric derived from Bland-Altman plots. A total of 20 MRI examinations are planned for this phase of the study.

Analysing the retinal perfusion by ASL to be able to figure out if the decreased visual acuity has an ischemic etiology.