Diet, or what we put in our bodies, can play a big part in Dry Eye.
Smoking has a direct link with Dry Eye and your Optometrist will have already advised you to stop.
A healthy diet rich in Omega 3 fatty acids can help too. If you don't like oily fish then consider a good quality supplement or old fashioned Cod Liver oil. Vitamin D can also play a role in healthy tear films. Adequate levels are tricky to achieve from diet alone and in northern countries it makes sense to take a supplement.