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Evaporative dry eye more common than pure aqueous-deficient dry eye, study finds
Pure aqueous-deficient dry eye is less common that evaporative dry eye, as characterized by signs of meibomian gland dysfunction, according to a study. Increased dry eye severity was linked to patients who demonstrated signs of both MGD and aqueous tear deficiency.
“The terms ‘dry eye’ and ‘aqueous tear deficiency’ are often used interchangeably,” the study authors wrote. “The results of the present study, however, reveal that [dry eye disease] patients classified with pure [evaporative dry eye], as characterized by signs of MGD, were three to six times more common than purely aqueous-deficient patients.”
The observational cohort study across 10 sites in the United States and European Union analyzed both eyes of 299 dry eye and normal subjects over a 2-year period. There were 218 women and 81 men, and the average age was 46.3 years.
Subjects were classified as having pure aqueous-deficient dry eye with Schirmer values less than 7 mm and MGD grades of 5 or less. Subjects were classified with purely evaporative dry eye with MGD grades more than 5 and Schirmer values of 7 mm or more. Subjects were classified in the mixed category with a Schirmer value less than 7 mm and MGD grade more than 5.
The researchers classified 159 of the 224 dry eye disease subjects; 79 were classified as having MGD, 23 were classified as having pure aqueous deficiency, and 57 were classified as having both MGD and pure aqueous deficiency. The other 65 subjects did not exhibit signs of either MGD or pure aqueous-deficient dry eye despite showing other clinical signs consistent with a dry eye diagnosis.
“Understanding the primary disease process in individual [dry eye disease] patients may help identify therapeutic treatments that would best target the underlying pathways,” the authors said.