Graduated with Honours in Medicine, Surgery, and Obstetrics from the Royal College of Surgeons in Ireland and National University of Ireland in 1993. He gained full-certification in the United States Foreign Medical Graduates Examinations and held full registrations to practice in Singapore, Hong Kong, and Ireland. He later specialized in Ophthalmology, earned a Masters in Medicine (Ophthalmology) from NUS, and was appointed a Clinical Tutor in the Faculty of Medicine, and an adjunct research fellow at Singapore Eye Research Institute.

He gained full-certification from the International Council of Ophthalmology. Dr Chng received Fellowships from the Royal College of Surgeons of Edinburgh and Glasgow, College of Surgeons in Hong Kong, and the Academy of Medicine in Singapore. He also holds a Diploma in Aesthetic Medicine from the American Academy of Aesthetic Medicine.

Dr Chng has conducted and presented clinical research on Aspheric Wavefront Lenses, Mix and Match Presbyopic Lenses, and Multifocal Lenses. He has practiced as a Consultant in the Cataract and LASIK Service in a public institution and gained experience with microkeratome LASIK, Epi-LASIK, and Femto-Second LASIK with different technology flap creation and ablation platforms. He is experienced in presbyopia monovision, KAMRA Inlays, Sulcoflex Multifocal implant and Crystalens accommodating lenses.

He is an accomplished cataract and LASIK surgeon, and has given instructional lectures at the meetings of the American Society of Cataract and Refractive Surgeons and the European Society of Cataract and Refractive Surgeons.