Inclusion Criteria:  Patient over 18 years old starting first-line treatment for metastatic colorectal cancer including BEVACIZUMAB (AVASTIN®) Systemic or intraocular anti-VEGF treatment naïve ECOG ≤ 2  Exclusion Criteria:  Pregnant woman, Minor patient or under legal protection Person deprived of liberty or under guardianship Inability to undergo medical monitoring of the trial Impossibility of carrying out the OCT-A Patient with a contraindication to Tropicamide 0.5% eye drops Patient with a history of degenerative macular pathology, vascular macular pathology or presenting an epiretinal membrane with traction phenomenon. Diabetes Patient for whom it is not possible to schedule an ophthalmology consultation before the start of treatment.