Ophthalmology can be defined as the medical-surgical speciality dedicated to preserving, restoring, rehabilitating and promoting the health of the organ of vision and its related structures in the general context of human beings and their relationship with the environment. It therefore deals with all knowledge about the visual system and its diseases.

The continuous growth in knowledge and technological complexity in the speciality has given rise to sub-specialities, which can be defined as specific, exclusive areas within the speciality. The Ophthalmology field has seen significant advancements in diagnostic and therapeutic techniques, examination methods and surgical procedures in recent years, leading to an increase in the speciality's instrumental complexity and causing ophthalmologists to focus almost exclusively on specific areas within the discipline. This has resulted in experts who are sub-specialised in different areas of Ophthalmology: anterior and posterior segment, glaucoma, neurophthalmology, paediatric ophthalmology, oculoplastics and orbit.

Despite its distinct identity, Ophthalmology has a close relationship with General Medicine and other medical disciplines. Indeed, the extensive range of ocular manifestations in systemic diseases leads to a high level of communication and collaboration with other specialities.