John Marshall is Frost Professor of Ophthalmology at King’s College London. His research in biomedical applications of lasers resulted in computer controlled Excimer lasers for the correction of human refractive errors. This created a new field of eye surgery and 30 million individuals have benefited from Excimer procedures. It seems delightfully ironic that his many awards include the Lord Crook Gold Medal of the Worshipful Company of Spectacle Makers. He was also responsible for the introduction of the first Diode laser for treating diabetic retinopathy, glaucoma and age-related macular degeneration. He has also made a major contributions to codes of practice protecting the public from damaging effects of lasers and other artificial light sources.