Tears keep your eyes moist, lubricate the surface of the eye for eyelid closure and guard against infection. They also wash away allergens and protect the eye. Without tears, good vision is impossible. Dry eye syndrome is a group of disorders affecting the film of tears over the eye. In the U.S., about six million women and three million men have moderate or severe symptoms of dry eye syndrome, and it is estimated that an additional 20 to 30 million people have mild cases of dry eye syndrome. Dry eye syndrome is one of the most common reasons that people visit their eye health professional. The condition affects women two to three times more than men.
Dry eye occurs most often in people older than 40. Although the cause of dry eye syndrome is unknown, it tends to occur more often in women. An even more pervasive problem, eye allergies affect an estimated 80 million Americans. External factors may aggravate dry eye symptoms, including conditions common in many workplace environments such as prolonged computer use and exposure to air conditioning, heating, dust and allergens. Not to be confused with dry eye syndrome, eye allergies are a reaction to substances in the environment that can result in some of the same types of discomforts associated with eye dryness.
When you have dry eye syndrome, either you don't produce enough tears, or you have unstable tears and/or excessive tear evaporation. Either problem causes your eyes to sting or burn, feel scratchy, become irritated and excessively tear. It most commonly occurs in both eyes, but may affect one eye more than the other. People with dry eyes have difficulty wearing contact lenses. They also may develop stringy mucus in or around their eyes. There can be pain and redness in the eye, or blurred, changing or decreased vision. People with more severe cases of dry eye often are also sensitive to light. Although eye infections are more common in people with dry eye syndrome, irreversible vision loss from dry eye is rare. More commonly, people with dry eye have fluctuating vision, and experience problems with tasks requiring visual concentration such as reading and driving. Most people with dry eye find the condition to be an uncomfortable nuisance, with many characteristics of a "chronic pain" type of syndrome.
The tear film on your eyes actually consists of the following three major components:
Lipid. The outer layer of the tear film is covered by an oily layer produced by meibomian glands in the lower and upper eyelids. This layer smoothes the eye's surface and keeps tears from evaporating too fast, and helps them stay on the eye.
Aqueous. The aqueous component is a watery layer that is produced by the lacrimal glands. This layer makes up most of what we normally consider tears. It nourishes the cornea (the clear tissue of the outer protective layer of the eye that transmits light) and the conjunctiva (a thin, clear layer of tissue that covers the white outer surface of the eye). This tear layer also cleanses the eye and washes away foreign particles or irritants that are wrapped up by the other major component - mucin.
Mucin. The goblet cells of the conjunctiva, as well as the surface cells of the cornea and the conjunctiva produce this protective lubricant of tears. It helps spread the watery layer of tears across the eye to keep the eye wet and it traps and wraps up foreign pathogens and debris so they do not damage the ocular surface.
As we age, the eyes naturally produce fewer tears. However, sometimes, the lipid and mucin layers produced by the eye are so unstable that tears can't remain on the eye long enough to keep it lubricated. Consequently, some people with dry eye may actually have tears running down their cheeks! Dry eye syndrome, also called keratoconjunctivitis sicca or ocular sicca, is the result. Although the exact cause of the problem is unknown, the American Academy of Ophthalmology reports that growing evidence suggests dry eye might be connected to changes in the function of the lacrimal gland and the surface of the eye.
Dry eye occurs most often in older women. Information gathered from the Women's Health Study, a large cohort study in which 25,665 postmenopausal women provided information about the use of hormone replacement therapy (HRT), suggests that those who use HRT, particularly estrogen alone, are at increased risk of dry eye syndrome. A relatively uncommon, but often more serious form of the disorder is associated with rheumatoid arthritis or dry mouth, and is called Sjögren's syndrome. Sjögren's syndrome is an autoimmune disease that attacks the body's lubricating glands, such as the tear and salivary glands. Allergies can also contribute to eye dryness, causing additional eye discomforts such as itchiness, redness, swelling and wateriness.
Although dry eye syndrome has no cure, its symptoms can be treated. Over-the-counter artificial tears that lubricate the eye are the main treatment. Sterile artificial eye ointments are often used at night to help lubricate the eye during sleep and to treat the scratchy eye feeling that many dry eye sufferers have when they wake up. Avoiding anything that can exacerbate eye dryness-such as hair dryers, rooms with low humidity, air conditioning or heat in cars (especially when vents are positioned directly at your face) wind and cigarette smoke-is recommended. In cases of moderate to severe dry eye, tears can be conserved by placement of a temporary or permanent plug into the channel at the inner corner of the eyelid where tears drain into the nose and the back of the throat.
Dry eye occurs most often in people older than 40. Although the cause of dry eye syndrome is unknown, it tends to occur more often in women. An even more pervasive problem, eye allergies affect an estimated 80 million Americans. External factors may aggravate dry eye symptoms, including conditions common in many workplace environments such as prolonged computer use and exposure to air conditioning, heating, dust and allergens. Not to be confused with dry eye syndrome, eye allergies are a reaction to substances in the environment that can result in some of the same types of discomforts associated with eye dryness.
When you have dry eye syndrome, either you don't produce enough tears, or you have unstable tears and/or excessive tear evaporation. Either problem causes your eyes to sting or burn, feel scratchy, become irritated and excessively tear. It most commonly occurs in both eyes, but may affect one eye more than the other. People with dry eyes have difficulty wearing contact lenses. They also may develop stringy mucus in or around their eyes. There can be pain and redness in the eye, or blurred, changing or decreased vision. People with more severe cases of dry eye often are also sensitive to light. Although eye infections are more common in people with dry eye syndrome, irreversible vision loss from dry eye is rare. More commonly, people with dry eye have fluctuating vision, and experience problems with tasks requiring visual concentration such as reading and driving. Most people with dry eye find the condition to be an uncomfortable nuisance, with many characteristics of a "chronic pain" type of syndrome.
The tear film on your eyes actually consists of the following three major components:
Lipid. The outer layer of the tear film is covered by an oily layer produced by meibomian glands in the lower and upper eyelids. This layer smoothes the eye's surface and keeps tears from evaporating too fast, and helps them stay on the eye.
Aqueous. The aqueous component is a watery layer that is produced by the lacrimal glands. This layer makes up most of what we normally consider tears. It nourishes the cornea (the clear tissue of the outer protective layer of the eye that transmits light) and the conjunctiva (a thin, clear layer of tissue that covers the white outer surface of the eye). This tear layer also cleanses the eye and washes away foreign particles or irritants that are wrapped up by the other major component - mucin.
Mucin. The goblet cells of the conjunctiva, as well as the surface cells of the cornea and the conjunctiva produce this protective lubricant of tears. It helps spread the watery layer of tears across the eye to keep the eye wet and it traps and wraps up foreign pathogens and debris so they do not damage the ocular surface.
As we age, the eyes naturally produce fewer tears. However, sometimes, the lipid and mucin layers produced by the eye are so unstable that tears can't remain on the eye long enough to keep it lubricated. Consequently, some people with dry eye may actually have tears running down their cheeks! Dry eye syndrome, also called keratoconjunctivitis sicca or ocular sicca, is the result. Although the exact cause of the problem is unknown, the American Academy of Ophthalmology reports that growing evidence suggests dry eye might be connected to changes in the function of the lacrimal gland and the surface of the eye.
Dry eye occurs most often in older women. Information gathered from the Women's Health Study, a large cohort study in which 25,665 postmenopausal women provided information about the use of hormone replacement therapy (HRT), suggests that those who use HRT, particularly estrogen alone, are at increased risk of dry eye syndrome. A relatively uncommon, but often more serious form of the disorder is associated with rheumatoid arthritis or dry mouth, and is called Sjögren's syndrome. Sjögren's syndrome is an autoimmune disease that attacks the body's lubricating glands, such as the tear and salivary glands. Allergies can also contribute to eye dryness, causing additional eye discomforts such as itchiness, redness, swelling and wateriness.
Although dry eye syndrome has no cure, its symptoms can be treated. Over-the-counter artificial tears that lubricate the eye are the main treatment. Sterile artificial eye ointments are often used at night to help lubricate the eye during sleep and to treat the scratchy eye feeling that many dry eye sufferers have when they wake up. Avoiding anything that can exacerbate eye dryness-such as hair dryers, rooms with low humidity, air conditioning or heat in cars (especially when vents are positioned directly at your face) wind and cigarette smoke-is recommended. In cases of moderate to severe dry eye, tears can be conserved by placement of a temporary or permanent plug into the channel at the inner corner of the eyelid where tears drain into the nose and the back of the throat.
Hiç yorum yok:
Yorum Gönder