Inherited retinal diseases associated with single gene disorders affect about 1 in 4,000 people and although individually rare, as a group are the commonest cause of severe visual impairment in the working age population. The final common pathway to blindness is impaired function or death of photoreceptors. There is considerable phenotypic and genetic heterogeneity with variable visual prognosis. Some disorders present in infancy with severe visual impairment whilst in other conditions the first symptoms appear in adult life. In most cases the disease is confined to the eye, but the underlying genetic mutation(s) may result in syndromic disorders with additional involvement of other organs.  There have been a number of scientific advances that have had a major impact on the field in recent years. These include improved retinal imaging, including the ability to image individual photoreceptor cells in the human eye, next generation sequencing  which has allowed a precise molecular diagnosis in the majority of patients and animal and iPSC models of disease which can be used to explore potential therapeutic approaches. Recently the first gene replacement therapy for an infantile onset retinal dystrophy has been approved by the FDA and is in current clinical practice.  A number of other gene based clinical trials are underway.  This brief talk will discuss how precise molecular diagnosis and deep phenotyping has led to improved understanding of molecular pathogenesis and informed the development of clinical trials of novel therapies.