Conditions involving the growth of blood vessels (angiogenesis) in the eye are the major cause of untreatable blindness and impaired vision in the Western world. The focus of Reinier Schlingemann's research is mainly on the role of growth factors in angiogenesis and wound healing in the eye. In addition, he conducts research into the mechanisms that cause diabetic retinopathy and age-related macular degeneration. With his research, Schlingemann has played an important role in the introduction of new medicines that inhibit angiogenesis. In addition to this more fundamental research, he has also set up a trial centre within his department for ophthalmic clinical studies. Schlingemann has also played an important role in establishing a network of similar centres in the Netherlands. Under his leadership, in 2008 this network started a major nationwide comparative study into the angiogenesis inhibitors Avastin and Lucentis in treating age-related macular degeneration.
Since 1996, Schlingemann has worked as an ophthalmologist and as head of the Ocular Angiogenesis Group at the UvA Academic Medical Centre (AMC). Previously, he had worked as a researcher in London and Oklahoma City and at the University of Leiden and Radboud University Nijmegen. Schlingemann was also affiliated with the Moorfields Eye Hospital in London as fellow ophthalmologist and senior honorary registrar. Schlingemann is a member of the board of the National Foundation for the Blind and Visually Impaired and the Netherlands Macular Degeneration Workshop of the Netherlands Ophthalmic Society. He was also a member of the editorial committees of the Nederlands Tijdschrift voor Geneeskunde (Netherlands Journal of Medicine), the Nederlands Tijdschrift voor Diabetologie (Netherlands Journal of Diabetology) and Framingham on Ophthalmology. For his research into eye conditions caused by diabetes, Schlingemann has received various project grants from the Netherlands Diabetes Fund. In 2008, he was awarded an Effectiveness Grant from the Netherlands Organisation for Health Research and Development.