Blepharitis occurs when something (usually chronic inflammation) causes the meibomian glands become clogged. Less oil is contributed to the tear film, meaning that the tear film evaporates more rapidly, rendering the surface of the eye drier.
When any fluid evaporates, it reduces the temperature of the surface it was on very slightly – and the cornea actually has nerves that can detect these small temperature changes. What happens next is that your body responds by telling the lacrimal gland to produce more tear fluid. This means, paradoxically, that you can have “watering” eyes because of dry eye!
In early stages, “plugs” appear on the edge of the eyelid which block the openings of the sebaceous glands. In this case, a simple mechanical cleaning can be effective.
However, if the inflammation of the eyelid margin is not treated for years, the eyelid will change anatomically. The edge of the eyelid becomes increasingly rounded and is no longer able to distribute the tear film on the surface of the eye, similar to a windscreen wiper with gaps on the Windshield.
More and more symptoms like burning and biting and also blurred vision will develop
In addition, systemic diseases such as psoriasis (rosacea), diabetes, polyarthritis, lupus erythematosus and Sjögren syndrome can cause dry eyes. Hormonal changes (such as those caused by hormone replacement therapy during menopause and contraceptive pills) are also a potential cause of dry eye syndrome. Other chronic inflammatory diseases like Crohn’s disease and ulcerative colitis can lead to a dry eye, because of the strong diarrhea and nutrient malabsorption.
Dry eye is not an immediate danger to vision – almost nobody will go blind thanks to it. But in most cases, it degrades people’s quality of life, often greatly.
The symptoms in the dry eye are varied and range from mild to massive: eye burning and biting, blurred vision, double vision, and headache, and unfortunately a lot of modern life can exacerbate this, as these symptoms typically occur more frequently after prolonged computer work, television viewing, and reading (be it a tablet, smartphone, or even an old-fashioned book).