In rosacea, the pathologic process of lesions on the face seems to be the very same that accounts, at least indirectly, for all the different manifestations of the disease at the eye. They are a consequence of inflammation in and around infundibula of the eyelashes as well as of the infundibula-like funnels that connect meibomian glands with the lid margin. McCully and Sciallis, in two articles that appeared in 1977 and 1983 were the first to suggest a connection between blepharitis involving openings of meibomian glands and a reduced tear film. Lemp and coworkers demonstrated in 1984 that a reduced tear film is found in many patients with rosacea of the eye. Gudmundsen et al., in 1992, stated clearly that a connection existed between inflammation at the openings of meibomian glands and the finding of "dry eye" in patients with rosacea because the lipid layer of the tear film is reduced and the film breaks. Ulceration of the cornea ("keratitis") in rosacea develops only consequent to the broken tear film and is accompanied by conjunctivitis. These changes are not specific for rosacea but may develop in any condition that reduces the tear film markedly. It is therefore not surprising that the most common manifestation of rosacea of the eye is blepharitis, the second most common is a "dry eye," and only rarely, the full picture of keratitis develops. If keratitis develops, patients also will complain about photophobia and in time, vision will be impaired.

From the finding of a "dry eye" alone, it cannot be inferred that a patient has rosacea and neither can it from conjunctivitis and keratitis. Only the association with typical infundibulocentric inflammation on the eyelid margin allows a diagnosis to be made with specificity, especially when the rest of the face also shows lesions diagnostic of rosacea.

Despite the considerable effort made in the research of ophthalmology to the understanding of rosacea of the eye, little of it has found entry in the literature of dermatology. Some of the confusion in the literature of ophthalmology results from imprecise terminology, but there is also poor correlation with rosacea when it affects the skin of the rest of the face. Rosacea serves as a good example for showing that it is worthwhile to approach diseases of the skin from an interdisciplinary perspective.