* Benzalkonium chloride, a preservative used in saline solution can increase<unk><unk>  up speed, so it is important to choose preservative free saline solutions for moistening the flourescein strip. * Localised corneal surface abnormalities can produce dry spots in that location and can give a falsely low<unk> -up<unk> . To avoid this error, repeat measurements should be taken. Appearance of dry spots in the same location in repeated procedures can indicate a surface abnormality in that area. * Touching the cornea with flourescein strip can cause excessive<unk> ing and will affect the<unk> .
Tear break-up time
Tidal volume
Cup-to-disc ratio
Ultraviolet index
Neurological pupil index
FEV1/FVC ratio
Electrochemical skin conductance
NC ratio