title: [But and Schirmer test comparative study in relation to dry eye etiology and severity].
abstract: OBJECTIVE
  To determine possible differences between the Schirmer test and the tear break up time (BUT) in relation to the etiology and severity of the dry eye syndrome.
  
  
  METHODS
  We present a prospective study of 206 eyes in 106 patients (38 males and 68 females). Both the Schirmer test and BUT were performed on all of them. We divided the patients into ten etiologic groups according to the Madrid triple classification of dry eye etiology and into four groups according to clinical severity.
  
  
  RESULTS
  Both the Schirmer test and BUT results decrease according to the severity of symptoms and we found significant differences between clinical groups. In regard to etiology, we found lower values of the Schirmer test especially in immunological, senile and traumatic dry eye groups. BUT measures were lower in immunological, inflammatory and tantalic dry eye groups.
  
  
  CONCLUSIONS
  Although we found differences between Schirmer test results and BUT values according to dry eye etiology, these differences were only statistically significant between the immunological group and the other groups. Differences between etiological groups decreased with worsening of the illness due to a general affectation of the lacrimal glands.
authors.affiliation: Hospital Central Cruz Roja, Madrid, España. docsantilopez@hotmail.com
authors.forename: J S
authors.initials: JS
authors.lastname: López García
authors.forename: I
authors.initials: I
authors.lastname: García Lozano
authors.forename: A
authors.initials: A
authors.lastname: Smaranda
authors.forename: J
authors.initials: J
authors.lastname: Martínez-Garchitorena
mesh_terms: D003941:Diagnostic Techniques, Ophthalmological; D015352:Dry Eye Syndromes / Q000175:diagnosis* / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012720:Severity of Illness Index