Dr Hammerton completed his training at the Adelaide University Medical School in 1977 (M.B.B.S.). He qualified as an ophthalmologist (eye specialist) in 1983 (F.R.A.N.Z.C.O., F.R.A.C.S.) at the age of 28. He pursued further advanced training in London at the Hospital for Sick Children, Great Ormond Street and Moorfields Eye Hospital. He was Lecturer and Research Fellow in the Institute of Child Health at the University of London and Senior Registrar at the Great Ormond Street Hospital.

On returning to Adelaide, he joined the current private practice where he has practiced general ophthalmology for over 30 years. 

His practice has largely been in the fields of cataract surgery, glaucoma management, treatment of diabetic eye disease, treatment of macular degeneration and medical laser treatments, paediatrics, strabismus, eyelid surgery and craniofacial ophthalmology.

In later years, he ceased general paediatric practice and limited this to craniofacial paediatric ophthalmology and management of children with rheumatoid conditions and genetic conditions.

He has been an ophthalmologist with the Australian Cranio-maxillo Facial Unit for 30 years, making him one of the most experienced craniofacial ophthalmologists. 

When he returned from London he was a consultant ophthalmologist in the public health system for 17 years at the Royal Adelaide Hospital, Women’s & Children’s Hospital (ACH) and Queen Victoria Maternity Hospital.

Over the years he has been involved in teaching and examining at pre and post graduate levels, having been a lecturer in the Post Graduate Diploma of Child Health course at the University of Adelaide and examiner in physiology in the Royal Australia New Zealand College of Ophthalmologists for 10 years. He tutors craniofacial fellows annually.

He has authored and co-authored numerous academic papers on subjects including the effects of anaesthetic agents on intraocular pressure, the effects of various skin conditions on the eye, the eye conditions associated with juvenile rheumatoid arthritis, eye conditions associated with craniofacial disorders, the causes of blindness in South East Asian countries and management of ocular burns. He conducted research into the infant corneal endothelium and electro-diagnostic assessment of visual acuity. He also conducted research into the development of enzyme replacement for children with mucopolysaccharidosis.

He has authored and co-authored several chapters on cranio-maxillo facial trauma, including the development of the published illustrations.

He has illustrated (as medical artist) a chapter on sporting injuries of the groin (osteitis pubis).

He has served as Chairman of the Qualification and Education Committee for the South Australian branch of R.A.N.Z.C.O. and as the South Australian branch Secretary.

He was a founding member of the Board of the South Australian Save Sight Foundation, Sight for All, and undertook projects in Sri Lanka, Myanmar, Vietnam, Laos and Cambodia under the Sight for All banner. He continues to support its valuable work. He has also provided services to Australia’s own Indigenous Health Program covering the area from Port Augusta to Maree.