Visual phenotyping at the Institut Clinique de la Souris

Visual diseases come in many flavors, with a large variety of affected tissues (eye anterior segment, retina, optic nerve, cortex …), ages of onset, rates of progression and causal factors. In Western countries, if the majority of these diseases are now curable, millions of people are still affected by blindness or low vision, as many retinal diseases (age‐related macular degeneration, retinitis pigmentosa, diabetic retinopathy, glaucoma…) still lack efficient treatments. In a facility devoted to mouse phenotyping, it is thus of major importance to propose an efficient visual phenotyping platform, to pick up visual defects in screened mutants, to assess the beneficial effects of potential treatments or the eventual adverse effects of drugs targeting the CNS – vision screen being mandatory in CNS drug development. While the tests performed in human clinics are transposable to rodents, the small eye size of the mouse hinders a fine assessment of the retinal fundus, especially in the periphery. To maximize our chances to detect even early phenotypes, we are moving toward a recently developed fundus imaging system (Paques et al., IOVS 2007), which allows to acquire high quality digital images of the fundus, up to the ciliary margin, and fluorescein angiography, allowing for a later diagnostic confirmation by ophthalmologists. Together with slit lamp examination and electroretinography, this constitutes a solid first line of visual phenotyping.