MUC5AC and dry eye syndrome: Quantitative KCS is a result of deficiencies in both the mucin, the inner layer, and lipid, the outer layer, of the tear film which can be identified by the tear break up time (TFBUT), with the use of topical fluorescein to define the areas of mucin absence [13,15,17] or a Meibometer to measure the level of lipids on the eyelid margin [13,22,23].