Day blind sheep and the importance of large animal disease models

摘要

The retina is a multilayered extension of the brain that plays a key role in vision. It is composed of many cell types, among them the rod and cone photoreceptors located in the outer retina that contain the light-activated opsin pigments. Rods only function under very dim light conditions, which are rarely encountered in our modern civilisation (we are usually exposed to some light, even at night). For our daily visual performance we rely more on cones than rods, since they are responsible for day vision, central visual acuity and colour perception. Loss of cone photoreceptors and their function leads to severe visual disability, as demonstrated by the many diseases affecting the retina, including the inherited retinal degenerations retinitis pigmentosa (RP) and age-related macular degeneration (AMD). AMD is the leading cause of blindness in adults over 60 years of age, and the number of AMD patients is expected to grow as baby boomers advance into their 60s and 70s. In order to develop new therapies to preserve cone function and prevent patients from going blind, researchers try to gain a better understanding of the molecular and cellular disease mechanisms affecting cones. Strategies to elucidate such mechanisms include the study of primary cone diseases such as achromatopsia.