Mr Duguid graduated in medicine from Aberdeen University and trained in ophthalmology in Glasgow, Melbourne, London and Paris. He was registrar and senior registrar in Moorfields Eye Hospital and then subspecialised in vitreo-retinal surgery as a fellow at Moorfields and Hopital Lariboisiere in Paris. He was appointed to the Western Eye Hospital (Imperial College Healthcare NHS Trust) as a consultant in 2001. Amongst his clinical roles there, he is in charge of the Eye Accident and Emergency department.

He specialises in medical and surgical diseases of the retina, cataracts and ocular trauma. He is also experience in medical management of glaucoma and general ophthalmic conditions. Medical retinal disease includes diabetic retinopathy, age-related macular degeneration (wet and dry types), retinal vascular occlusions, sickle-cell retinopathy and myopic maculopathy. Surgical retinal disease includes retinal detachment, macular hole, epiretinal membrane and advanced diabetic retinopathy. Mr Duguid is also able to offer small-gauge vitrectomy.

He is a Consultant adviser in Ophthalmology to the Civil Aviation Authority (CAA) and holds regular clinics at their headquarters in Gatwick. He is also a Designated Aviation Ophthalmologist to the Civil Aviation and Safety Authority of Australia (CASA) and sits on the Vision Panel for the Department of Transport.