Lysosomal enzymes in human tear fluid collected by filter paper strips

Protein concentrations and lysosomal enzyme activities in tear fluid collected by filter paper strips were studied. The magnitude of the wetted area on the filter paper did not affect the apparent protein concentration in the tear fluid. Lysosomal enzyme activities in tear fluid were higher than those in serum. The pH and enzyme activity curves in tear fluid were similar to those in serum. The optimal pH of acid phosphatase, beta-D-glucuronidase, N-acetyl-beta-D-glucosaminidase, alpha-L-fucosidase and alpha-D-mannosidase in tear fluid were determined.