iii) Conjunctival sampling Step 1: Request the participant to direct his/her gaze in the infero-temporal direction. This exposes the superior nasal bulbar conjunctiva for impression. Step 2: Apply the EyePRIM membrane to the area. Step 3: Ensure good apposition of the membrane with the conjunctiva. Do this by rocking the EyePRIM membrane to the left and right. Step 4: Remove the membrane from the conjunctiva with a peeling-like movement. Step 5: Exert greater force on the EyePRIM spring mechanism. After a "click" sound, the membrane will be ejected from the gadget. Place the membrane from the right eye into the "right" eppendorf tube. Step 6: Repeat for the superior temporal bulbar conjunctiva, this time directing the participant's gaze infero-nasally. Place this membrane into the "right" eppendorf tube. There should be 2 membranes in this eppendorf tube. Step 7: Place this tube in the box of ice. Step 8: Repeat steps 1-7 for the other eye, but place the membranes into the "left" eppendorf tube. Step 9: At this point should have both "right" and "left" eppendorf tubes, each with 2 membranes within them immersed in 1.5ml of RPMI medium. Place them in the ice box.