I become aware of dry eye issues and the importance of tears. I copy a substantial part of the article “Facts About Dry Eye” from this web page https://nei.nih.gov/health/dryeye/dryeye.
Dry eye can be associated with:
. inflammation of the surface of the eye, the lacrimal gland, or the conjunctiva;
. any disease process that alters the components of the tears;
. an increase in the surface of the eye, as in thyroid disease when the eye protrudes forward;
. cosmetic surgery, if the eyelids are opened too widely.
. What is the cornea?
The cornea is the clear, dome-shaped outer surface that covers the eye in front of the iris, the colored part of the eye. The cornea helps protect the rest of the eye from germs, dust, and other harmful matter. The cornea bends, or refracts, light entering the eye, and accounts for most of the eye’s total focusing power. It also serves as a filter to screen out most of the damaging ultraviolet (UV) wavelengths in sunlight.
[Cornea] it has no blood vessels to nourish or protect it against infection. Instead, it receives its nourishment from the tears and the watery fluid (aqueous humor) that fills the chamber behind it.
. What are tears, and how do they relate to dry eye?
Tears, made by the lacrimal gland, are necessary for overall eye health and clear vision. Tears bathe the surface of the eye, keeping it moist, and wash away dust and debris. They also help protect the eye from bacterial and other types of infections.
Tears are composed of three major components: a) outer, oily, lipid layer produced by the meibomian glands; b) middle, watery, lacrimal layer produced by the lacrimal glands; and c) inner, mucous or mucin layer produced by goblet cells located within a thin transparent layer over the white part of the eye and covering the inner surface of the eyelids. Tears are made of proteins (including growth factors), electrolytes, and vitamins that are critical to maintain the health of the eye surface and to prevent infection.
Tears are constantly produced to bathe, nourish, and protect the eye surface. They are also produced in response to emergencies, such as a particle of dust in the eye, an infection or irritation of the eye, or an onset of strong emotions. When the lacrimal glands fail to produce sufficient tears, dry eye can result.
Any disease process that alters the components of tears can make them unhealthy and result in dry eye.
. What are the symptoms of dry eye?
Dry eye symptoms may include any of the following:
. stinging or burning of the eye;
. a sandy or gritty feeling as if something is in the eye;
. episodes of excess tears following very dry eye periods;
. a stringy discharge from the eye;
. pain and redness of the eye;
. episodes of blurred vision;
. heavy eyelids;
. inability to cry when emotionally stressed;
. uncomfortable contact lenses;
. decreased tolerance of reading, working on the computer, or any activity that requires sustained visual attention;
. eye fatigue.
. Causes and Risk Factors
What are the causes of dry eye?
Dry eye can be a temporary or chronic condition:
. Dry eye can be a side effect of some medications, including antihistamines, nasal decongestants, tranquilizers, certain blood pressure medicines, Parkinson’s medications, birth control pills and anti-depressants.
. Skin disease on or around the eyelids can result in dry eye.
. Diseases of the glands in the eyelids, such as meibomian gland dysfunction, can cause dry eye.
. Dry eye can occur in women who are pregnant.
. Women who are on hormone replacement therapy may experience dry eye symptoms. Women taking only estrogen are 70 percent more likely to experience dry eye, whereas those taking estrogen and progesterone have a 30 percent increased risk of developing dry eye.
. Dry eye can also develop after the refractive surgery known as LASIK. These symptoms generally last three to six months, but may last longer in some cases.
. Dry eye can result from chemical and thermal burns that scar the membrane lining the eyelids and covering the eye.
. Allergies can be associated with dry eye.
. Infrequent blinking, associated with staring at computer or video screens, may also lead to dry eye symptoms.
. Both excessive and insufficient dosages of vitamins can contribute to dry eye.
. Homeopathic remedies may have an adverse impact on a dry eye condition.
. Loss of sensation in the cornea from long-term contact lens wear can lead to dry eye.
. Dry eye can be associated with immune system disorders such as Sjögren’s syndrome, lupus, and rheumatoid arthritis. Sjögren’s leads to inflammation and dryness of the mouth, eyes, and other mucous membranes. It can also affect other organs, including the kidneys, lungs and blood vessels.
. Dry eye can be a symptom of chronic inflammation of the conjunctiva, the membrane lining the eyelid and covering the front part of the eye, or the lacrimal gland. Chronic conjunctivitis can be caused by certain eye diseases, infection, exposure to irritants such as chemical fumes and tobacco smoke, or drafts from air conditioning or heating.
. If the surface area of the eye is increased, as in thyroid disease when the eye protrudes forward or after cosmetic surgery if the eyelids are opened too widely, dry eye can result.
. Dry eye may occur from exposure keratitis, in which the eyelids do not close completely during sleep.
How is dry eye treated?
Depending on the causes of dry eye, your doctor may use various approaches to relieve the symptoms.
Dry eye can be managed as an ongoing condition. The first priority is to determine if a disease is the underlying cause of the dry eye (such as Sjögren’s syndrome or lacrimal and meibomian gland dysfunction). If it is, then the underlying disease needs to be treated.
. What can I do to help myself?
. Use artificial tears, gels, gel inserts, and ointments – available over the counter – as the first line of therapy. They offer temporary relief and provide an important replacement of naturally produced tears in patients with aqueous tear deficiency. Avoid artificial tears with preservatives if you need to apply them more than four times a day or preparations with chemicals that cause blood vessels to constrict.
. Wearing glasses or sunglasses that fit close to the face (wrap around shades) or that have side shields can help slow tear evaporation from the eye surfaces. Indoors, an air cleaner to filter dust and other particles helps prevent dry eyes. A humidifier also may help by adding moisture to the air.
. Avoid dry conditions and allow your eyes to rest when performing activities that require you to use your eyes for long periods of time. Instill lubricating eye drops while performing these tasks.