The eyes don't make enough tears, and the eye cannot be comfortably hydrated
The eye produces tears which are flawed. They often lack one or more essential parts normally included in tears to allow them to properly coat and hydrate the eye.
Red eyes are generally not as worrisome as dry eye syndrome and you shouldn't worry too much about them. In most cases, red eyes are caused by allergens or foreign substances, which can cause your eyes to become irritated. Small blood vessels throughout your eyes then become inflamed and enlarged, becoming much more visible and turning your eyes a reddish hue. This is where the term “red eyes” comes from.
The leading defense against either of these forms of dry eye syndrome is a type of specialty eye drops called “artificial tears.” These special eye drops combat the uncomfortable symptoms of dry eye syndrome by imitating real tears as closely as possible. In order to do this in the best way possible, there are many different formulations of artificial tears. Each formulation addresses a different underlying cause of your dry eye. Some help to to address the issues of dry eye syndrome in which tears are lacking in quantity, and others will add one or more building blocks to your tears to help them better perform their intended function., Dr. Yamanaka, Los Alamitos eye doctor.
A not of caution, however: The great number of conditions that can cause dry eyes makes it very hard to know exactly what the cause may be sometimes. If your red eyes are accompanied by a high fever, headache and/or a great deal of eye pain, go to the doctor immediately. This note aside, red eyes are almost always minor and should not cause anxiety unless accompanied by these additional symptoms.
Even with a brief but comprehensive explanation such as this, it can sometimes be hard to tell the difference between these two similar looking conditions.