Dry Eyes A Close Look
When our eyes are not sufficiently moistened by tears, a condition known as ‘dry eye’ occurs. It is a result of our eyes not producing enough tears, or if the quality of tears produced by the tear glands is poor. Keratoconjunctivitis sicca is the medically defined term for dry eye. Our tears are a healthy mix of water, proteins, fatty oils and electrolytes. This ensures that our eyes are always kept smooth and clear, besides providing nutrition and preventing infections. Tears are of two types, basic and reflex. The basic tears naturally produced by the lacrimal glands (tear glands) lubricate and nourish the eyes, while the reflex tears are generated in response to emotional stimuli or irritation. Tears spread over the eye like a transparent film. The tear film consists of three layers: oil, water, and mucin. All of them are critical in their composition, to ensure a good quality and quantity of tears. Fatty oils known as lipids, which form the first layer, reduce the evaporation of water content from our eyes and lubricate the eye lids as they blink over the globe. The small glands in our eyelids (meibomian glands) produce them sufficiently. Next is the middle layer, which is mostly water with a bit of proteins and electrolytes. This layer provides oxygen to the cornea, cleanses the eye, and keeps it free of particles or foreign bodies. It also prevents infections. The inner layer of mucin spreads tears evenly over the surface of our eyes.
- Ageing: Tear production tends to fall with the process of ageing. Dry eyes are common in people older than 50.
- Hormonal changes: Hormonal changes, such as in postmenopausal women, may induce dry eyes.
- Medical conditions: Rheumatoid arthritis, systemic lupus erythematosus, scleroderma, Sjogren’s syndrome, thyroid disorders, diabetes and vitamin A deficiency.
- Occupational hazard: Working on computers for long hours.
- Environmental conditions: Dusty, smoky or polluted air, extreme weather conditions of hot, dry or windy climate, etc.
- Infections: Infections of the lid like blepharitis and meibomianitis, might cause deficiency of oil component and poor quality of the tear film, resulting in dry eye.
- Medicines: Medicines like antihistamines, antidepressants, and diuretics are known to induce dry eyes, and also birth control pills and pain relievers such as ibuprofen.
- Prolonged contact lens usage is also known to cause dry eyes.
- Tear gland damage: Inflammation or radiation that damages the tear glands can upset tear production.
- Laser eye surgery: Refractive eye surgeries such as LASIK might cause a temporary reduction in tear production, leading to dry eyes.
Eyelid problems: Eyelids that don’t function properly due to any medical conditions or illnesses may cause dry eye. When it becomes difficult to blink, tears may not be adequately spread across the eyes or they might evaporate too quickly. Apart from all these above, a poor quality diet, deficient in vitamin A or omega-3 fatty acids, might precipitate symptoms of
The doctor will examine your eye and the tear film using an instrument called the slit lamp.
Special tests or investigations:
- Tear film break up time: This indicates the stability of the tear film.
- Rose Bengal test: This is a dye used to assess the extent of damage to the ocular surface.
- Schirmer test: This test is to measure tear production. A small paper strip is inserted in the lower eyelid and removed after a few minutes. The damp area is measured in millimetres. The extent of dampness helps to determine the presence and severity of dry eye.
Complications are generally rare. Significant dryness of the eye can lead to increased risk of serious eye infection. Ultimately, scarring, thinning and even perforation of the cornea may occur. As a result, vision and even the eye itself may be permanently lost.
Treatment and drugs
- In those cases, where the medication is the cause, a different medication may be recommended without the observed side effects. In the case of an eyelid condition such as an anatomic abnormality or a condition that makes it difficult to close the eyelids completely, an oculoplastic surgery may be required. Autoimmune conditions such as rheumatoid arthritis or Sjogren’s syndrome may be diagnosed and evaluated by a rheumatologist.
- Artificial tears: Artificial tears are the mainstay of treatment of dry eyes. A variety of artificial tears are available in the market and the best may be chosen as per the doctor’s recommendation. The main disadvantage of eye drops is the short duration of action and development of sensitivity to preservatives. This can be avoided by using preservative free medication.
- Preservative and non-preservative drops: Shelf life of some eye drops is prolonged with the addition of preservatives. Non-preservative eye drops come in single-use vials that are thrown away after the usage. If the eye drops are prescribed for more than four times a day, non-preservative drops are safe.
- Gels and ointments: Gels are more preferable than eye drops because they need to be instilled less frequently. Ointments provide longer relief from the symptoms of dry eyes, by coating the eye with a thin film of lubricant. But ointments are thick and can generally make the vision a little cloudy. Ointments are thus best used just before bedtime. The frequency of medication depends on the intensity of thesymptoms and whether they are persistent.
- Antibiotics: Certain conditions of the eyelid, like blepharitis or meibomian gland dysfunction that causes dry eye, require antibiotics, both topical and oral. Tetracycline and doxycycline are prescribed not only to reduce the infection but also to make the oil more fluid so that it flows out of the oil glands easily.
- Anti-inflammatory agents: Immune suppressing medications like cyclosporine or those containing corticosteroids are used to control inflammation. Inflammation on the surface of the eye decreases the ability of the eye to maintain a healthy tear film. They should be used only under the doctor’s supervision. They might be required in cases of moderate to severe dry eyes.
- Special contact lens usage: Special contact lenses are available to ensure that the surface of the eye is protected or shielded by trapping moisture close to the eyes, to help relieve dry eye symptoms.
Ocular inserts: Moderate to severe eye dry eyes that can’t be controlled using artificial tears, might require tiny eye inserts that resemble a clear grain of rice in transparent gels. The hydroxypropyl cellulose (LACRISERT) is inserted between the lower eyelid and eyeball, once a day. The insert dissolves slowly, ensuring the slow release of a suitable nutrient, used in eye drop lubricants.
- Closure of tear ducts: Tear ducts normally drain tears away. This is partially or fully closed using tiny silicone plugs. This helps to conserve both the natural tears and the artificial tears instilled as a result of medication. These plugs can be removed or left in. Another procedure called thermal cautery uses heat to close the ducts. The area is anaesthetically numbed and then a hot wire is applied that shrinks the tissues of the drainage area, causes scarring, which then closes the tear duct.
- Eyelid surgery: If a person has difficulty in closing the eyes for any reason, resulting in dryness of the eye, this can be relieved by sewing the lids together laterally, a procedure known as tarsorrhaphy.
If we are careful enough to avoid situations that precipitate dry eyes symptoms, we would do well in preventing its occurrence.
- Stay away from exposing the eyes to direct air blow, especially fans, air conditioners, car heaters, hair dryers, etc.
- Avoid being in dry atmosphere for long periods of time, but if one has to, use a humidifier.
- Wear sunglasses outdoors and goggles while swimming. Choose eyeglass shields for the tops and sides of eyeglasses to protect the eyes from dry air and wind.
- Stop or quit smoking. Smoking worsens dry eye symptoms.
- Drink eight to 10 glasses of water daily.
- Wear computer glasses on the recommendation of the doctor, if the usage is persistent and more than two hours daily.
- If one’s work requires long hours of staring at the computer screen, ensure that the screen is always kept below the eye level. If the screen is positioned above, the eyes open wide and could lead to faster evaporation of tears between eye blinks. Make a conscious effort to blink regularly. Ensure that the eyes are at least 25 to 30 inches from the screen.
- Ensure that the workstation or the work environment is adequately lit. In today’s world, dry eye is largely reckoned as a common disorder of the eye impacting a significant percentage of the population. Proper care with sensible precaution can help in avoiding it.