Tear film flow and stability in herpes simplex keratitis and chronic blepharitis.

Tear film flow and stability studies were carried out in patients suffering from herpes simplex keratitis and chronic blepharitis by performing Schirmer test I and tear film break-up-time (BUT) measurements. In herpes simplex keratitis the values of BUT were within normal limits. Values of Schirmer test I were significantly higher (t-test, P less than 0.001) in these patients and are considered to be due to reflex hypersecretion of tears. Schirmer test I was found to be unaffected, whereas the values of BUT seen were significantly lower (t-test, P less than 0.001) in patients suffering from chronic blepharitis. These lower values of BUT can perhaps be attributed to the altered resurfacing of precorneal tear film as a result of changes in the lid margins.