Objective: To evaluate the correlations of the fluorescein clearance test (FCT) and the Schirmer 1 test with the severity of corneal epithelial and eyelid disease in normal patients and patients with tear film disorders due to meibomian gland disease (MGD) and/or aqueous tear deficiency (ATD).
Methods: Nineteen normal control subjects, 16 patients with MGD associated with rosacea, 21 patients with noninflammatory atrophic MGD, and 43 patients with ATD were enrolled. There was a similar age and sex distribution in each group. Each patient completed a symptom severity questionnaire that consisted of 11 questions and then underwent a panel of diagnostic tests in the following order: assessment of corneal and conjunctiva sensation with the Cochet-Bonnet esthesiometer, FCT, assessment of corneal fluorescein staining, Schirmer 1 test (5 minutes without anesthesia), and biomicroscopic examination of the eyelid margins and meibomian glands. The FCT was performed with a fluorophotometer by measuring the fluorescein concentration in minimally stimulated tear samples collected from the inferior tear meniscus. By studying the best area under the receiver operating characteristic curves, we developed a formula that combined the FCT and Schirmer test results, which we termed the FCT corrected by Schirmer test.
Results: The FCT showed stronger correlation with ocular irritation symptoms (r = 0. 35, P <.001), corneal fluorescein staining (r = 0.54, P<.001), and meibomian gland and eyelid pathologic signs than the Schirmer 1 test. A correction factor that was based on the best area under the receiver operating characteristic curves, added to the FCT score, improved its correlation with ocular irritation symptoms, eyelid margin and meibomian gland pathologic signs, and ocular surface sensitivity scores.
Conclusions: Corneal epithelial disease is correlated with decreased aqueous tear production and delayed tear clearance, whereas eyelid and MGD are correlated with delayed tear clearance. The FCT corrected by Schirmer 1 test improves the correlations of the FCT with ocular irritation symptoms, corneal epithelial and eyelid pathologic signs, and corneal and conjunctival sensitivity for patients with MGD and ATD.