The potential causes of red dry eyes are numerous. Some of these causes might require medical expertise, but many others are of no consequence. They can include simple eye allergies, exposure to dust and other foreign bodies, dry air or more serious conditions, such as trauma or infection.
Red dry eyes are often associated with fairly simple causes. Being continuously awake for an extended period of time can produce red dry eyes, and severe fatigue has also been found to create these same symptoms. The redness in the eyes happens when blood-vessels in the sclera, the white portions of the eyes, become dilated, enlarged or irritated. The dryness is often classified as a gritty or sandy sensation. In response to this, an excessive amount of eye watering might occur, though often with no relief.
Eye irritation is another leading cause of red dry eyes and can be attributed to a number of reasons. Foreign particles enter the eye on a frequent basis and can cause eye irritation that leads to redness and dryness. People who wear contacts are prone to developing red dry eyes because of the amount of moisture necessary to keep the eyes in proper working condition.
Many mild disorders and diseases are capable of inducing red dry eyes as well. Conjunctivitis, often referred to as pink eye, is a common eye infection that causes these symptoms. Pink eye is the inflammation of the conjunctiva, a layer of membrane that covers the surfaces of the eye and inner eyelid, and it can result from an allergic reaction or an infection, most often viral. This condition tends to be more of a moderate inconvenience, though some manifestations can be painful, as is the case of acute pyogenic bacterial conjunctivitis.
Another disorder known to cause red dry eyes is called, simply, dry eyes. This dry eye syndrome is caused by insufficient tear production, whether in quantity or quality. It can be caused by blepharitis, an inflammation of the eye lid margins often owing to a bacterial infection in which the invading bacteria produce a toxic waste. Blepharitis can cause tears to evaporate more quickly than normal, leading to red dry eyes.
Dry eye syndrome can also be the result of excessive computer use. When most people use the computer, they involuntarily reduce the rate at which they blink. Normally, people blink at a rate of 22 times per minute, but when using the computer, people tend to blink at a rate of seven times per minute. Infrequent blinking leads to increased evaporation of eye moisture, which then causes red dry eyes.
Red dry eyes also can be an indication of an injury or trauma to the eyes, such as a corneal abrasion, which is a cut or scrape on the clear protective layer on the front of the eye. A common eye injury, a corneal abrasion occurs when foreign substances, such as sand or dirt, enter the eye and scratch this outer layer. This trauma-related irritation can then manifest with symptoms that include red dry eyes.