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.
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