What is dry eye and what are the symptoms?
Answer: Presents with scratchiness, burning sensation, foreign body sensation, blurred vision, fatigue, and difficulty in opening the eyes in the morning. It has adverse effects on the quality of life since it is persistence.
Lately, we have heard of it more frequently; so, is it a new disease caused by current vital conditions?
Answer: As a matter of fact, it dates back to older times but it has been newly defined by scientific studies and developments within 20 years.
It was used to define as lack of tear and associated dryness of the eye surface but now it is considered a disease in which inflammatory response and immune system play an important role.
In addition, current conditions have a role in occurrence and perception of the disease.
Why is the tear so important?
Answer: The tear plays an important role in moisture on the surface of the eye and protection from germs and improving the quality of vision.
The eye lids easily slide and move over the front part of the eyeball through the tear.
The tear also contains protection molecules such as lactoferrin and lysozyme producing a natural defense system against germs. So, the germs on the surface of the eye are diactivated initially by washing by the tear or breaking down by this defense system.
On the other hand, the tear covers the surface of the transparent layer which we call the cornea as a thin layer and improves the quality of vision.
Where is the tear produced?
Answer: The tear is produced by the lacrimal glands situated in the upper, outer portion of each orbit, in the lacrimal fossa of the orbit formed by the frontal bone, and also by auxiliary lacrimal glands in the eyelids and conjunctiva. It is secreted all day to keep the surface of the eye moist at all times.
If the tear is constantly secreted then why doesn’t tear fall from our eyes constantly; which mechanism does control that?
Answer: The produced tear FLOWS INTO THE NOSE THROUGH LACRIMAL DUCT.
A reflex network comprised of lacrimal glands, brain and nerve system connecting the two moisturizes the surface of the eye. So, the sensitive nerve endings on the eye surface transmit the requirement of moisten to the brain and the stimulus from the brain activates the lacrimal glands so that adequate amount of tear can be produced for the eye surface and distributed over the surface of the eye thorough eye lids.
What is dry eye syndrome caused by?
Answer: There are a lot of causes. It is best to categorize these causes:
Dry eye syndrome can be divided into two subgroups, decreased moisten of surface of the eye associated with low production of the tear and increased vaporization of the tear.
Decreased production of the tear is likely to occur with diabetes mellitus that reduces the sensitivity of the surface of the eye; infections caused by herpes; refractive surgeries, e.g. Lasik, that aims at correcting the refractive errors of the eye; use of contact lenses; and advanced ages.
The amount of the tear can also be decreased by various diseases such as trachoma, chemical burns, and lymphoma sjögren’s syndrome.
On the other hand, structural and functional disorders of edge of eyelids and sebaceous glands may result in loss of tear on the eye surface due to vaporization and thus dry eye syndrome.
The trouble is that once the dryness has occurred and aggravated, it is likely to increase because of vicious cycle.
How does use of a computer affect dry eye?
Answer: Use of a computer is a typical example of dry eye syndrome associated with increased vaporization.
In fact, we forget to blink our eyes when we focus on working at the computer. The studies have revealed that the move of eyelids is decreased 5 times more at the computer. Therefore, the tear is unlikely to spread over the surface of the eye through eyelids and the tear available here is vaporized and decreased, resulting in dryness of the area of eyelid space.
So, we unconsciously get dry eyes at a computer.
To avoid that, we should blink more frequently at the computer, take a break of work, and keep the screen as low as possible from the eye level.
Do contact lenses have any effects on dry eye?
Answer: Contact lenses also produce dryness, causing vaporization of the tear. In addition, they desensitize the cornea and slightly affect the production of the tear.
However, this effect is reversible and may disappear after removing the contact lenses.
Placement of the most suitable CL for the eye, careful selection of CL solutions, and use of artificial tear drops when required may reduce the problems.
Why is the incidence of dry eye higher in women; does menopause have any effects on it?
Answer: The incidence of dry eye is indeed higher in women, especially after the menopause. Although the estrogen hormone decreased with the menopause was initially held responsible, a serious of scientific studies has indicated that in addition to estrogen hormone, androgen hormone is more effective on the tear functions.
So, the level of both of the hormones is actually decreased with menopause, or rather, the ratio of estrogen and androgen hormones is changed. The incidence of dry eye after menopause increases with age-related changes.
Is it treatable?
Answer: First of all the cause of dry eye should be found in treatment of dry eye.
In addition to treatment of the primary disease, lack of tear should be met; inflammation should be suppressed; and response of immune system should be controlled as it is immune-originated inflammatory disease.
It will also be beneficial to drink a lot of water, eat food such as fish rich in omega 3, and avoid environmental factors, e.g. air condition and wind.