Sajjad is a consultant ophthalmologist at Moorfields Eye Hospital and professor of corneal regeneration at the Institute of Ophthalmology, University College London (UCL), and the Moorfields-UCL NIHR Biomedical Research Centre. As well as managing general corneal diseases and cataract and refractive surgery, he is best known for his clinical expertise in complex inflammatory ocular surface diseases and ocular surface reconstruction with stem cell therapies. He also runs a lab group at UCL with a research interest in corneal epithelial healing and limbal stem cells.