Dry eye is one of the most common reasons making people visit eye clinics. This syndrome, which is the result of change in the tear quality or quantity, can affect all age groups, but its occurrence is higher among the elderly. Moreover, this disease afflicts women more than men. Symptoms of this disease vary from slight itchy and burning eyes while using eyes a lot to corneal perforation in very serious cases.
Natural Tear Secretion
The main duty of eye tear is to keep eyes moist and continuously wash the surface of eyeball as well as feed the cornea with oxygen and food. Tear is made up of three layers:
• The Deep Mucous Layer: this layer covers the cornea and conjunctiva and helps the watery layer of tear to spread through the eye surface.
• The Middle Watery Layer: this layer makes up the main part of tear. Most of this layer (98%) contains water, and the rest contains salts and proteins. Most of the watery layer of tear is secreted from the lacrimal gland located outside and above the eyeball below the upper eyelid.
• The Outer Oily Layer: this layer, which is secreted from the glands existing on the eyelid's edge, covers the watery layer and prevents it from rapid evaporation.
Each time a person blinks, the tear layer covers the eye. Extra tear drains off through two small ducts in the inner corner of eyelids into the nose, which is why crying causes a runny nose.
Dry Eye Causes
Generally, every factor that reduces the production or changes the quality of tear can lead to dry eye. The most important causes of dry eye are as follows:
• Aging: as people get older, the secretion quantity of the tear watery layer decreases. In addition, as the elderly's skin grease decreases and it goes dry, oil secretion in their eyes also decreases and, as a result, evaporation of the watery layer increases. Reduction of production and the increase in evaporation of the watery layer of tear cause dry eye in most of the elderly.
• Environmental Factors: the evaporation rate of the watery layer of tear increases in hot and dry environments. Furthermore, exposure to strong wind and/or cold and dry weather in the heights can deteriorate dry eye. Using heating devices (such as heaters and furnaces) and exposure to dust and smoke (especially cigarette smoke) are among the factors that aggravate dry eye.
• Using Eyes for Long Periods of Time: enough blinking is necessary for the tear layer to spread through the eye. In cases when the person gazes at something for a long time without blinking (for example, while working with a computer, watching TV or studying), symptoms of dry eye become worse.
• Medications: many of the ordinary medications can decrease tear secretion and cause dry eye. The most important medications causing this are:
o Antihypertensive medications
o Cold medicines (e.g. antihistamines)
o Heart disease medications
o Many of the eye drops (especially those used to treat glaucoma)
• Hormonal Imbalances: hormonal imbalances can result in dry eye due to changes in the tear layer's oil. Menopause, pregnancy, and contraceptives aggravate dry eye because of hormonal imbalances they cause.
• Diseases: different diseases like thyroid diseases and some of the autoimmune diseases (such as sjogren's syndrome and lupus) can cause dry eye.
• Nutritional Deficiencies: lack of vitamin A can lead to severe and dangerous dry eye.
• Eyelid Inflammation (Blepharitis): this disease deteriorates dry eye by changing the tear layer's oil.
• Lagophthalmos: if eyelids do not properly close due to structural problems, the evaporation level of tear increases and dry is created. Moreover, in cases when the person blinks less often than normal because of neurological problems (such as Parkinson's disease), dry eye is caused.
• Wearing Contact Lenses: using contact lenses is one of the common reasons of dry eye. Contact lenses absorb the watery layer of tear like a sponge and cause dry eye. In addition, wearing contact lenses reduces corneal sensation and blinking and, as a result, causes trouble in tear production and spread.
Symptoms and Signs of Dry Eye
Although this disease has been named dry eye, the patient does not feel his/her eyes are dry in most cases but complains about itchy and burning eyes and sometimes excessive tearing. The most commonly observed symptoms of dry eye include:
• Itchy and burning eyes
• Foreign body sensation (like grit) in the eye
• Blurred vision solved by blinking
• Red eyes
• Sensitivity to light
• Excessive tearing
• contact lens intolerance
These symptoms usually develop in both eyes. Severity of the symptoms is not the same in different periods of time and often worsen after being exposed to wind and dust, working with a computer, watching TV, or studying for a long time.
How to Diagnose Dry Eye
In case you suspect dry eye because of the symptoms above, make sure you discuss it with a doctor. Keep in mind that dry eye not only causes discomfort but may also result in leukoma and permanent poor vision in severe cases.
In order to examine and diagnose dry eye, ophthalmologists used different methods:
• Observing the tear layer on the eye surface using a slit lamp.
• Coloring the eye surface using special colors: these colors stick to the dry and damaged areas of the eye and recognize them.
• Measuring the amount of tear with a special paper (Schirmer's test): in this method, a special paper filter is placed inside the eyelid and examined after some minutes. The amount of moisture absorbed by the paper filter is related to the tear secretion level.
• Investigating the chemical compounds of tear: in this method, which is used in specific cases, the amount of salts and proteins of tear is investigated.
Dry Eye Treatment
It must be noted that the consequences of dry eye could be either very slight or very severe. In very slight cases, simply following general advice improves the symptoms. In more severe cases, however, a variety of treatment measures may be required.
• Have enough drinks during the day. This helps to keep the tissues of the body, and eye surface in particular, moist.
• While using your eyes for a long time, try to blink intentionally. Do not stare at the monitor screen, TV screen, or the book. Every 5 to 10 minutes, close your eyelids for some seconds.
• Avoid exposure to dust or cigarette smoke. Wear glasses (sunglasses or eyeglasses) as far as possible in dry environments and stormy conditions
• Use humidifiers to keep your room moist during cold seasons when heating instruments are used at home.
• Do not rub your eyes. This would stimulate and deteriorate the symptoms.
• Notice when the symptoms get better and when they get worse.
• Avoid factors like overheating the room, hair dryer, dust, and smoking, which may cause dry eye.
Medical Treatment for Dry Eye
• Artificial Tears: the eye drops are the most common medicines used to treat dry eye, and they usually control the symptoms of dry eye. In slight cases, using artificial tears for 3-4 times a day would suffice to control the symptoms. These drops are produced in different pharmaceutical factories. It is possible that the products of one particular factory have more compatibility with your eyes. Therefore, you had better identify different products with your doctor and select the one with more compatibility with your eyes. Some types of eye drops are quickly drained off the eye and suppress the symptoms for a short time. some other types of eye drops, however, have more viscosity and stay in the eye for a longer period of time and their effect would last for some hours. An important point is that some artificial tears contain preservatives which stimulate and aggravate eye symptoms in some people. Therefore, consult with your doctor and use eye drops without preservatives, especially if you use them frequently (i.e. more than 4 times a day).
• Eye Ointments: in cases when dry eye symptoms persist while sleeping, it is recommended that simple eye ointments be used before sleeping.
Using ointments is not recommended during the day because they cause blurred vision and lessen the effects of artificial tears.
• Edible Antibiotics: in cases when eyelid inflammation and fat glands play a role in creating dry eye, taking edible antibiotics under the ophthalmologist's supervision sometimes helps to improve the symptoms.
• Using Baby Shampoo: in cases when eyelid inflammation has caused dry eye, washing their edges with diluted baby shampoo helps to improve the symptoms by removing extra fat.
Dry Eye Surgical Treatments
In relatively severe dry eye cases, sufficient improvement may not be reached by above mentioned measures. Using surgical methods is necessary in such cases.
• Blocking Tear Ducts: in this method, the ducts through which tear comes out are blocked temporarily or permanently. As blocking the kitchen sink with a hole cover makes water stay in the sink, blocking tear ducts makes tear stay in the eye and keep it moist.
• Closing the Eyelids: in cases when ptosis or structural problems of eyelids cause the eye to be left open and tear to evaporate, blocking a part of the eyelids temporarily can reduce the evaporation level of tear and help to treat dry eye.
• Corneal Transplantation (Keratoplasty): in cases when severe dry eye has caused keratoleukoma or keratohelcosis, corneal transplantation might be required to improve vision. However, the result of this surgery is usually not very good in such cases.
In very severe cases of dry eye, a serum eye drop has to be produced from the patient's own blood to be used as an artificial tear. This drop contains blood nutrients and considerably improves dry eye.
To cure dry eye, many other actions such as using PROSE lenses can be taken, which will be explained to you by the ophthalmologist.
Dry Eye and LASIK
The presence of dry eye can affect the result of corrective eye surgeries (like LASIK). Normally, if dry eye exists, corneal repair will be done with a delay after surgery. In addition, people suffering from dry eye are more likely to face consequences after eye surgery. Furthermore, dry eye symptoms usually worsen after the LASIK. Therefore, if you have dry eye symptoms and intend to do LASIK do not forget to consult with the ophthalmologist in this regard.
Keep in mind that curing dry eye is important not only for eye comfort but also for eye health and maintain vision.
Dry Eye Brochure