It is rather common for a person who has visited an ophthalmologist with various complaints of discomfort in their eyes to learn that they have dry eyes which require treatment with eye drops. This section will deal with everything that may pertain to ‘dry eyes’.
Dryness of the eyes is a situation in which the surface of the eye (mainly the transparent cornea) is not sufficiently covered and bathed by a fluid-lipid layer in order to ensure constant moisture. In a natural, healthy state there are tiny glands that secrete lipids, next to which are found tear glands that secrete liquid. The liquid’s job is to wet the surface of the eye and avoid drying of the cornea, whereas the lipid component serves to create a fatty ‘membrane’ over the liquid (similarly to the fatty layer which floats on the surface of chicken soup) which protects this liquid from evaporation. When the lipid layer is not sufficient, the eye will become dry even if there is an adequate amount of tears. The opposite is true as well: without the liquid component, the lipid layer is not enough in order to protect the eye from dryness.
If so, in ‘dry eye patients’ the front surface of theirs eyes is not covered in an adequate manner by a fluid-lipid layer (fluid + lipid mixed up) and as a result, the cells that cover the cornea suffer. This dryness will manifest itself as a feeling of discomfort in one’s eyes, occasionally accompanied by the feeling of a foreign body (as though one has a sand grain in the eye), slight redness, a desire to rub the eyes, and excessive tearing. Yes!, as a result of dryness the tear glands will secrete in excess, but without the lipid layer this fluid cannot satisfactorily fulfill its purpose. Please note, this is not a mistake, people who complain of tearing (too many tears) will occasionally be diagnosed as suffering from dry eyes.
The feeling of dryness is not constant throughout the day: it increases on hot days, in the wind, with air-conditioning, and particularly while watching television or working on the computer for extended periods of time, as well as while reading for long stretches of time. This is a result of the fact that when we are focused on something (such as a book or the TV) or while performing a task that demands concentration, we blink far less often. Blinking is essential for spreading tears over the entire surface of the eye. In the summer, of course, dryness is more pronounced. One would think that merely asking patients to blink more often would solve the problem. But it simply doesn’t work that way. Blinking is a reflex which we are not aware of most of the time. We cannot force ourselves to blink and at the same time concentrate on another task, it simply doesn’t work.
How is dryness treated? There are many types of artificial tears which serve to replace the lack of natural tears. They exist as both drops and as ointments. As a rule: drops are used during the day, and ointments are used before going to sleep and in cases of extreme dryness. There are many preparations on the market (more than 10 different kinds), produced by different companies. As they do not require a prescription, you can go into any pharmacy and purchase any one of them. Many patients ask me which preparation is most recommended for dry eyes. My answer is that you simply need to try different types until you find the brand that is both effective and comfortable for your eyes, in exactly the same way that each person chooses which toothpaste and which shampoo they prefer most.
In general, dryness is not dangerous for the eye, and even without treatment it usually does not cause significant nor permanent damage to the eyes. Therefore patients in my care learn that drops (or ointments) for dryness are used in order to feel better, and so that the eye will feel more comfortable, and not because the treatment is necessary from a ‘health’ point of view.
Of note, there is one type of dryness which is very severe and which might endanger the eye and vision, which is fortunately very rare, occurs in the setting of serious disease such as bone-marrow transplantation, severe rheumatic diseases, radiation therapy and harsh chemical burns to the eye. However, those few patients who belong to this group know that their eye involvement is serious and requires special and intensive treatment which also includes treatments for dryness). Naturally, unless you were specifically told so by your ophthalmologist, you do not belong to this extremely rare and unusual group.
In summary, ‘dry eyes’ is a benign irritating condition which may be a nuisance, but is not dangerous to the eye in any way. It is related to a lack of either fluid or lipids which intermix and moisten the surface of the eye. As a result, dryness develops, expressed as a feeling of sand in the eyes, discomfort, redness, or occasionally excessive tearing. The treatment of ‘dry eyes’ is by instilling moistening drops called ‘artificial tears’ that can be purchased over the counter in any pharmacy. These drops have to be placed in the eye multiple times during the day, in proportion to the amount of dryness the person suffers from, the amount of discomfort one experiences, as well as the climate on that particular day. Generally, there is no limit on the amount of drops that one can instill, since no damage will be caused to the eye as a result of intensive treatment composed of too many artificial tears. The treatment of dry eye should alleviate the symptoms, is simple and convenient. However, it does not heal (solve) the condition and hence necessitates the use of treatment in a chronic fashion.
One final remark: occasionally a patient who was diagnosed as suffering from dry eyes will begin treatment with artificial tears in a consistent manner but will not experience relief of his symptoms. If increasing the treatment (using more drops during the day) does not lead to any improvement, there is the possibility that the symptoms from which the patient suffers are the result of a different problem rather than ‘dry eyes’. In these situations it is worthwhile to consider returning to the ophthalmologist for another eye exam. Perhaps the doctor will discover additional findings that will direct him to another diagnosis that requires additional treatment. This comment is important since dryness is a commonly made diagnosis, and occasionally behind this diagnosis, lies a different diagnosis which requires a different form of treatment in order to improve that patient’s symptoms and discomfort.