We have already addressed some of the major causes of aqueous deficient dry eye. Now I would like to address evaporative dry eye. This is usually caused by a problem with the lipid layer (the top fatty layer of the three layers of the tear film). However, anything that causes increased evaporation of the tears can do this. This includes decreased blinking (such as in Parkinson's disease), not closing the eyes all the way, and it can be induced by environmental conditions such as fans, etc. When the lipid layer is deficient, the tears evaporate more and the eye feels dry. Sometimes the tear film can actually be thicker than normal, but the symptoms are still there because the quality of the tear film is not ideal. I think the easiest way to think about this is to think of chapped lips. If your lips are dry, you can get them wet as much as you want, but they usually only get worse. You need chap stick to help keep the moisture in. The lipid layer does the job of chap stick. Now, the lipid layer is mainly produced by glands in the eyelid called meibomian glands. When these glands are dysfunctional, it will cause evaporative dry eye and we call it blepharitis. (There are several different types of blepharitis that cause different signs and symptoms). Blepharitis may be caused by rosacea, can worsen with age, or may even be aggravated by mites of the eyelashes. It is a very common condition. Often, I will look at the glands and they are almost gone from chronic obstruction. There are several basic treatments that may help including warm compresses, fish oil, and many more advanced treatments for more serious cases. Here at Reveal Eye Care & Surgery, I will consider restasis, xiidra, lipophilic tear solutions, steroids, topical and oral antibiotics, meibomian gland expression, and even meibomian gland probing, As you can see, there are many causes of dry eye, and one usually has to know the reason for the condition to effectively treat it.