As a participant in the study a sample of tears will be collected in a non-invasive manner by sitting comfortably at the slit lamp (a slit lamp is the standard device used to examine the eye and merely requires the participant to sit upright and place their chin on a chin rest and their forehead up against the slit lamp apparatus). The participant will then be asked to look upwards and while gently lowering the lower eyelid, a sterile blunt glass pipette will be used to collect tears from the natural tear lake (the tear lake is a reservoir of tears that sits on the surface of the eye and above the lower eyelid). Collected tears will then be taken for analysis of inflammatory markers.