Abstract
Purpose: :
Dry eye disease (DED) is a prevalent diagnosis among ophthalmic patients. Corneal permeability has been reported to change with ocular surface disease (eg DED). A simple, objective measurement of corneal permeability could prove useful in clinical diagnosis. Fluorophotometry has been shown as an effective technique to indirectly measure corneal permeability; we modified its use to provide a simple, minimally invasive metric to estimate corneal permeability and then correlate this metric with clinical tests of DED signs and symptoms.
Methods: :
All 43 subjects reviewed and signed IRB informed consent before completing DED clinical measurements of signs and symptoms, including: tear break up time (TBUT), Schirmer’s test, fluorescein staining, lissamine staining and Ocular Surface Disease Index (OSDI). Using the above measurements, each patient was assigned a clinical severity grade utilizing the International Dry Eye Workshop (DEWS) grading scale (three masked observers).To estimate corneal permeability using the FM-2 Fluorotron Master with a patient friendly technique, the following was done: two baseline scans were taken then 60 µL of 2% non-preserved fluorescein were instilled. One minute later a drop of proparacaine followed by 10 mL of non-preserved normal saline solution were added to remove any remaining fluorescein in the tear film. Fifteen minutes post wash two more scans were taken. For each patient a ratio was derived of post wash average to baseline average and used as an estimate of corneal permeability. The derived ratio was correlated with each clinical measurement as well as with the DEWS severity rating.
Results: :
Estimated corneal permeability, via fluorophotometry, demonstrated a correlation with DEWS severity grading as well as clinical measurements of DED. The strongest positive correlation exists between DEWS severity grading and corneal permeability (corr coeff = 0.60) followed by fluorescein staining, OSDI and lissamine staining with correlation coefficients of 0.42, 0.25 and 0.21 respectively. Negative correlations exist between corneal permeability and TBUT and Schirmer’s, demonstrating coefficients of -0.44 and -0.41 respectively.
Keywords: cornea: epithelium • cornea: tears/tear film/dry eye