Fluid uptake in Schirmer papers and its relevance to their employment in tear collection for lysozyme tests.

An investigation was undertaken into the relationship between the wet length of a standard Schirmer paper and the fluid weight in the 5 mm tip after a 5-minute moistening period. Immediate weighing after moistening showed that it is unreliable to infer a particular fluid weight in the 5 mm tip from a known wet length, and it is concluded that such papers will lead to error in lysozyme tests. If the papers are inserted for a period within sealed envelopes, there is found to be a close relationship between wet length and fluid weight in the tip, the papers reaching a stable state at 5 hours. Soaked Schirmer papers were shown to given particularly inconsistent results.