The "duh" take-home point here: If only a small minority (23/224, i.e. 10%) of dry eye patients actually have "true" aqueous deficient dry eye alone, then why would I treat the majority of my dry eye patients as though they did?
Distribution of Aqueous-Deficient and Evaporative Dry Eye in a Clinic-Based Patient Cohort: A Retrospective Study.
To evaluate in a general clinic-based cohort of patients with dry eye disease (DED) the distribution of patients with aqueous-deficient or evaporative subtype of DED.
Schirmer tests and meibomian gland dysfunction (MGD) (Foulks-Bron scoring) were evaluated in both eyes of 299 normal subjects and DED patients (218 women and 81 men) across 10 sites in the European Union and the United States. Using the more severe measurement of the 2 eyes, subjects were considered to have pure aqueous-deficient dry eye (ADDE) with Schirmer values of <7 mm and MGD grades of ≤5. Patients were classified as purely evaporative dry eye with MGD grades of >5 and Schirmer values of ≥7 mm. Subjects were placed into the mixed (hybrid) category if they exhibited both a low Schirmer value of <7 and evidence of MGD with a grade >5.
Of the 224 subjects classified with DED using an objective, composite, disease severity scale, 159 were classified into 1 of 3 categories: 79 were classified with only MGD, whereas only 23 were classified as purely aqueous deficient, and 57 showed evidence of both MGD and aqueous deficiency. Overall, 86% of these qualified DED patients demonstrated signs of MGD. The remaining 65 patients showed evidence of DED through other clinical signs, without overt evidence of MGD or ADDE, possibly because of the inherent variability of these signs.
The proportion of subjects exhibiting signs of evaporative dry eye resulting from MGD far outweighs that of subjects with pure ADDE [aqueous deficient dry eye] in a general clinic-based patient cohort.
Cornea. 2012 Feb 28. [Epub ahead of print]
Lemp MA, Crews LA, Bron AJ, Foulks GN, Sullivan BD.
*Department of Ophthalmology, Georgetown University, Washington, DC †TearLab Corporation, San Diego, CA ‡Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, UK §Department of Ophthalmology and Vision Science, University of Louisville, Louisville, KY.