Advances in dry eye

The ‘Dry Eye’ definition has matured and evolved over time motivated by advances in technology, knowledge, and understanding of the disease. When TFOS DEWS first presented a definition in 2007, it was defined as a ‘multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance and tear film instability with potential damage to the ocular surface.’ In 2017, the same group added to the definition the concept of ‘loss of homeostasis of the tear film,’ ‘hyperosmolarity,’ ‘inflammation,’ and ‘neurosensory abnormalities.’ All these made a more complete definition of this complex and multifactorial condition [1]. In 2017, the Asia Dry Eye Society (ADES) describes and emphasizes the concept of ‘unstable tear film’ in their definition of dry eye creating a simpler classification oriented to creating a simpler diagnosis and management of these patients [2]. Nowadays, thanks to proliferative research and hard work of different societies to try to bring clarity to a disorder with a high level of complexity, the multifactorial characteristic of Dry Eye Disease is better understood, as is the concept of the lacrimal functional unit (LFU) and its role in the production and maintenance of a healthy ocular surface tear film [3,4].