Abstract
Purpose: :
To define the interest of phenol red thread in diagnosis of severe ocular sicca syndrome, and to estimate the agreement with the Schirmer I test.
Methods: :
The PRT test was performed before (PRT1) and after (PRT2) the Schirmer I test (without anesthesia) in both eyes of 112 consecutive patients (72 patients complaining of ocular dryness secondary to primary or secondary Sjögren’s syndrome and 40 healthy volunteers). Only the lowest result for each test was used in statistical analysis. The patient and the control groups were matched for age and gender (mean age; 57.5 and 52.7 respectively)
Results: :
The ROC procedure showed weak sensitivity/specificity couples whatever PRT1 cut-off value. A cut-off value of 15mm for PRT2 provided the best ratio between sensitivity and specificity (68% and 90% respectively) and 10mm for Schirmer I test permitted a sensitivity of 77.80% and specificity of 82.50%. Agreement between PRT2 and Schirmer I test was significant. Combination of Schirmer I test (< or = 10mm), PRT2 test (< or =15mm) and negative "deltaPRT" (PRT2<PRT1) increased sensitivity and specificity to 83% and 100%, respectively.
Conclusions: :
Phenol red thread used alone doesn’t seem better than historic Schirmer I test for diagnosis of severe ocular sicca syndrome. In contrast combination of both tests statistically increases the power for detection of sicca patients.
Keywords: cornea: tears/tear film/dry eye • clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology