Inclusion Criteria:  Planned Photorefractive Keratectomy in both eyes Simple myopia or myopic astigmatism, refractive spherical equivalent between -0.50 and -9.0 diopters in both eyes with regular corneal topography  Exclusion Criteria:  Only one eye operated on At least one contraindication to refractive surgery, namely : keratoconus, minimum corneal thickness < 400 µm, severe dry syndrome, progressive corneal infection Personal history of corneal surgery Personal history of ocular pathology other than simple myopia or myopic astigmatism Pregnant or breastfeeding woman