The investigator, using sterile gloves, held
the upper lid up, and one piece of filter paper was placed on the
superior region of the conjunctiva for 5 to 7 seconds and was then
removed with blunt forceps and placed in a sterile prelabeled 2-mL
capped polypropylene centrifuge tube containing 1 mL of RLT
RNA Isolation Buffer (Qiagen, Gaithersburg, MD) with 0.01%
A-mercaptoethanol.