Dry eye disease (DED) is the most common ocular surface disease, characterized by insufficient production and/or instability of the tear film. Tear substitutes are usually the first line of treatment for patients with DED. Despite the large variety of tear substitutes available on the market, few studies have been performed to compare their performance. There is a need to better understand the specific mechanical and pharmacological roles of each ingredient composing the different formulations. In this review, we describe the main categories of ingredients composing tear substitutes (e.g., viscosity-enhancing agents, electrolytes, osmo-protectants, antioxidants, lipids, surfactants and preservatives) as well as their effects on the ocular surface, and we provide insight into how certain components of tear substitutes may promote corneal wound healing, and/or counteract inflammation. Based on these considerations, we propose an approach to select the most appropriate tear substitute formulations according to the predominant etiological causes of DED.

Advanced age is one of the most evident risk factors for dry eye disease (DED), with male/female sex, chronic drug consumption, and prolonged device use. This article aims to review the literature about the changes of the ocular surface associated with DED in the elderly and patients < 40 years. The pathophysiologic changes of the ocular surface responsible for eye dryness are linked with inflammation and neurosensory abnormalities and may occur with a different feature in young patients compared with elders. Peculiar treatment strategies may be needed for young and older subjects with DED.

The aim of our research was to obtain expert consensus for updated definition and classification of dry eye disease using formal methodology. The nominal group technique (NGT) involved a steering committee of four ophthalmologists began with collection of ideas followed by group discussion. The ideas were collated, refined, and voted upon. The main characteristics considered, each with different degrees of severity in types I, II, and III, were the ability or not of the ocular surface to re-equilibrate itself, frequency of symptoms, presence of inflammation, epithelial alterations, and possible alterations in the quality of vision. This was followed by three rounds of a “mini-Delphi” involving an expert panel of 13 ophthalmologists, with the last round including all 17 ophthalmologists. Consensus in the final round of voting (⩾75% of votes) was reached on the definition of dry eye disease and on criteria for its classification in three forms. Type I is a transient and reversible form with subclinical inflammation, possible epithelial alterations, and occasional alterations in vision. Type II is a recurrent form characterized by a reduced ability to re-equilibrate the ocular surface, frequent symptoms and alterations in vision with clinically-evident inflammation, and clear evidence of epithelial alterations. Type III is a chronic form with inability to re-equilibrate the ocular surface and accompanied by clinically-evident and chronic inflammation, persistent epithelial alterations, and frequent alterations in quality of vision. The vast majority of patients with dry eye disease can be easily classified into one of these three forms. Dry eye disease definition was updated accordingly.

Dry eye disease (DED) is a multifactorial condition resulting from reduced tear secretion from the lacrimal glands, increased tear water evaporation or the production of poor-quality tears. Such tear instability can lead to inflammation and damage of the ocular surface, as well as to abnormal nociception. Historically, tear substitutes and corticosteroids have been the bastion of DED therapy, but a substantial number of patients still suffer from residual symptoms even after being treated with traditional treatments. Aiming to find safe and effective alternative therapies, recent efforts have been focused on the role of vitamin D in the cellular physiology of the eye. Possibly because of its positive effect in modulating the immune and inflammatory responses, the systemic supplementation of vitamin D seems, indeed, to be an effective therapeutic strategy, especially, but not only, for patients affected by DED that does not respond to conventional treatments. In this context, this review focuses on the literature reporting on the pathogenesis and treatment of DED, with a special emphasis on the recent investigations reporting on the potential role of the systemic administration of vitamin D as a therapeutic approach in the management of such condition.