2. Non Invasive Tear Break-up Time (NIBUT) The Oculus keratographer 5M (Oculus, Wetzlar, Germany) will be used to perform the non-invasive tear break up time. Patient will sit comfortably in front of the instrument and blink freely while fixing on a target directly ahead. Once the patient is ready, patient will be instructed to blink twice and refrain from blinking. Keratograph 5M is fully automated and it will capture any break or distortion in the image and the time of the break will be noted. Three readings will be taken for each eye to get the average value. It is possible that the tear film of participants is more stable, i.e. increased tear break up time.