 Dry eye is a chronic irritating eye condition that affects many people, caused by poor tear quality and insufficient quantity. Treatments are traditionally in the form of artificial tears applied to the ocular surface. However, there is little evidence in the scientific literature that demonstrates their efficacy relative compared to each other, nor how to decide which one might be most effective for an individual patient. Therefore the investigators aim to examine the efficacy of different classes of artificial tears those designed to increase viscosity, reduce evaporation or to mimic the component balance of the natural tears. In addition, the investigators also aim to determine how the treatment preferred by an individual could potentially have been predicted from their baseline condition. 