Dry eye is a general term used to describe a heterogeneous group of diseases resulting from inadequate wetting of the cornea and conjunctiva by the precorneal tear film (PCTF). Millions of people worldwide suffer from dry eye.
Despite its high prevalence, dry eye is not always easy to diagnose. The vast majority of patients have symptoms that are mild to moderate in severity. Although these patients are mostly suffering from discomfort, objective signs of dry eye may be missed, and without proper diagnosis, patients may not receive the attention and treatment that this condition warrants.
What are the causes of dry eye or dry eye syndrome?
Dry eye is often a normal part of the aging process. Other causes include
- Abnormalities in the layers of the tear film
- Exposure to enviornmental conditions
- Injuries to the eye
- General health problems
- Certain medications
What are the signs and symptoms of dry eye or dry eye syndrome?
The symptoms of dry eye vary considerably from one individual to another. Most patients complain of a foreign body sensation, burning and general ocular discomfort. The discomfort is typically described as a scratchy, dry, sore, gritty, or burning sensation. Discomfort is the hallmark of dry eye because the cornea is richly supplied with sensory nerve fibers.
A significant percentage of patients also experience light sensitivity and blurry vision.
Individuals with dry eye commonly remark that their eyes tire easily, making it difficult for them to read or watch television. The reason for this difficulty is that the frequency of blinking typically decreases during tasks that require concentration. As blink frequency decreases, there is more time for the tear film to evaporate. If blinking is infrequent enough, it can result in the formation of one or more dry spots on the corneal surface.
Contact lens intolerance can also be a symptom of dry eye. Sometimes, a patient with mild to moderate dry eye may not experience symptoms until contact lenses are fitted. The placement of a contact lens can upset the delicate balance of tear film production and tear film distribution onto the surface of the eye, leading to contact lens intolerance.