Procedure using fluorescein dye * Fluorescein 2% is instilled into the lower fornix of patient's eye. Alternatively, impregnated flourescein strip moistened with preservative (benzalkonium chloride) free saline solution can also be used. * The eye is examined under a slit lamp with a low magnification and a broad beam covering the whole cornea. The lamp is switched to a cobalt blue filter. * The patient is asked to blink once and to keep their eyes open. * Due to the fluorescein, the<unk>  film will appear green in color. * A black spot indicating the dry area will appear a few seconds after each blink. *<unk>  is the<unk>  interval between the last blink and appearance of the first randomly-distributed dry spot. If the patient blinks before 10 seconds have elapsed, the test must be restarted. Taking two or more measurements and calculating its average may give a greater accuracy of measurement of<unk> . Non-invasive procedure In annon-invasive<unk>  measurement procedure, a grid or concentric ring pattern is projected onto the cornea and the patient is asked to blink. The rings will appear distorted when the cornea becomes dry. The<unk>  interval between the last blink and the distortion of the ring pattern gives the measurement of<unk> .
Tear break-up time
Tidal volume
Cup-to-disc ratio
Ultraviolet index
Neurological pupil index
FEV1/FVC ratio
Electrochemical skin conductance
NC ratio