Which study focuses on the eye and diseases affecting the eye?

Ophthalmology is the branch of medicine and surgery that is concerned with the diagnosis and treatment of eye disorders. This specialty focuses on various aspects of eye health, including the prevention and management of diseases such as glaucoma, cataracts, macular degeneration, and diabetic retinopathy. Ophthalmologists are medical doctors who have the training to conduct eye examinations, prescribe corrective lenses, perform eye surgery, and provide medical treatment for eye-related issues.

The other fields listed do not pertain specifically to eye health. Odontology relates to dentistry and the study of tooth development and diseases, oncology is the study of cancer and tumors, and oliguria refers to a medical condition characterized by abnormally low urine output. These disciplines focus on different areas of health and do not involve the study or treatment of eye diseases. Therefore, the correct answer, ophthalmology, accurately represents the field dedicated to understanding and addressing eye health and its related diseases.