Ophthalmology is a branch of medicine and surgery which deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a specialist in ophthalmology. The credentials include a degree in medicine, followed by an additional four to five years of ophthalmology residency training. Ophthalmology residency training programs may require a one-year pre-residency training in internal medicine, pediatrics, or general surgery. Additional specialty training (or fellowship) may be sought in a particular aspect of eye pathology. Ophthalmologists use medications to treat eye diseases, implement laser therapy, and perform surgery when needed.