By Eyecare NGIntroduction | The tear film | Causes | Conditions | Symptoms | Diagnosis | Treatment | Prevention
Dry eye syndrome or simply ‘dry eyes’ occurs when the front surface of the eye dries out either due to insufficient tear film, infrequent blinking or poor tear quality and quantity. It can affect people of all ages although it is more common in those aged 50 years and above. It affects more women than men, especially women undergoing menopause and those on hormone replacement therapy. Dry eyes can lead to eye irritations, inflammation, and scarring of the conjunctiva and cornea.
The tear film
The Tear film is the outermost layer of the front surface of the eye that keeps it moist, clean and free of dust, debris, and microorganisms. The human tear film is made up of three layers namely: oil (lipid) layer, watery (aqueous) layer, and the mucous layer.
Oily or Lipid Layer: This is the first layer of the tear film. It is oily in nature and it helps keep tears from evaporating too quickly from the surface of the eye. It is produced by the meibomian gland of the conjunctiva.
Watery or aqueous layer: This is the middle layer and largest component of the tear film. It is mainly made up of water and is responsible for washing away debris, dust and foreign bodies from the surface of the eye. It is produced by the lacrimal glands (located in the upper eyelids)
Mucous layer: This is the inner layer of the tear film. It is the layer that keeps the tear film together. It adheres strongly to the surface of the cornea and conjunctiva and helps spread the tears across the eye surface.
Causes of dry eye syndrome
Dry eye syndrome is caused by deficiencies in any of the components of the tear film.
- If the oily component is not sufficient or totally unavailable either due to clogged meibomian gland duct or the inability of the meibomian glands to produce enough oil, the tear film will evaporate easily and too quickly resulting to dry eyes.
- If the lacrimal gland fails to produce enough tears to cover the surface of the eyes, the eyes will become dry.
- If there is a deficiency in the mucous layer, the tear film will not stick properly to the surface of the cornea and conjunctiva resulting in dry eyes.
Conditions that cause or aggravate dry eyes
The following conditions can lead to dry eyes or make it worse.
Eyelid problems: Infrequent blinking and incomplete closure of the eyes during sleep can cause the tear film to evaporate quickly leading to dry eyes. Conditions such as nocturnal lagophthalmos and floppy lid syndrome which both leaves the eyeball partially exposed during sleep can cause or aggravate dry eyes. People who have undergone eyelid surgery due to in turning or out turning eyelids (entropion and ectropion respectively) may also suffer keratitis sicca (dry eyes associated with corneal inflammation) if the lid repair was too tight.
Systemic conditions: Diseases like diabetes, Sjogren’s syndrome, arthritis and Graves disease can cause dry eyes. They lead to dry eyes by causing deficiencies in one or more layers of the tear film. For instance, the manifestation of Grave’s disease in the eye known as Grave’s ophthalmopathy is characterized by protruding eyeballs. People with this condition suffer from dry eyes due to the evaporation of tears that result from the bulging eyeballs, incomplete blinking and partial closure of the eyelids
Aging: Dry eyes also tend to be very common with increasing age. As people get older, the quality and quantity of tears and tear film reduces resulting to dry eyes. This is common in people aged 50 years and above.
Hormonal changes: People on hormonal replacement therapy and menopausal women have dry eyes due to hormonal changes in the body.
Environmental conditions: Some environmental conditions like air conditioning, use of ceiling fans, air heating system, windy environment, dry weather and air pollution contribute greatly to dry eyes. Fans, air conditioners, and heating systems can reduce humidity in the room leading to faster evaporation of tears.
Some medications: Medications like antihistamines, antidepressants, some antihypertensive drugs and birth control pills can cause dry eyes. In addition to their side effects on the body, some of them, particularly the eye drops can also cause dry eyes through their interaction with the tear film or dehydrating effects on it.
Smoking: This affects tear film quality causing dry eyes.
Computer use: When people work on the computer, they don’t blink often. The tear film evaporates resulting to the dry eyes which most times is experienced as a burning sensation in the eyes.
Contact lens wear: Contact lenses may worsen an existing dry eye syndrome.
Symptoms of dry eyes
- Burning sensation
- Foreign body or gritty sensation
- Light sensitivity
- Feeling of dryness
- Blurred vision
To diagnose dry eye, your eye doctor will carry out some tests that are aimed at evaluating the quality and quantity of your tear film. Your eyes will be stained with special dyes and the amount of tears you produce will be measured. The stability of the tear film will also be assessed. The front surface of your eyes especially the cornea and the conjunctiva will be examined for signs of dryness, inflammation, and scarring. With the information gathered, a diagnosis can be made and the cause of dry eyes ascertained.
Treatment of dry eyes
The treatment of dry eyes will normally depend on the cause. Treatment yield better results if the exact cause of dry eyes is known. Here are some options for the treatment of dry eyes:
Medications: Eye lubricating drops (artificial tears) and gels are normally used to treat dry eyes. There are several over the counter eye drops for dry eyes. Your eye doctor may, however, prescribe prescription eye drops such as steroids and antibiotics depending on the severity of your dry eyes and associated inflammation.
Punctal plugs: This involves the use of sterile plugs to close the puncta (openings to the tear drainage system). This ensures more tears are retained on the surface of the eyes.
Meibomian gland expression: If the cause of dry eye is a clogged meibomian gland, your eye doctor will recommend opening up the clogged ducts so that they can function better. This can be done by applying warm compress or using lipiflow to unclog the ducts.
Nutritional supplements: People with dry eyes may benefit from nutritional supplements like Omega 3 fatty acids. This is because Omega 3 fatty acids cause anti-inflammatory effects and may boost the quality of the lipid layer of the tear film.
Treating underlying conditions: To get the best out of your dry eye treatment, your doctor would recommend treating underlying causes when necessary. For instance, if you have dry eyes due to lagophthalmos, you may be required to tape your eyelids during sleep.
Prevention of Dry eyes
Increase your water consumption. Drinking more water may help alleviate the symptoms of dry eyes or resolve the condition.
Keep your eyelids clean. This helps in taking care of lid conditions like blepharitis which may make dry eyes worse. Lid hygiene aids the production of the mucous component of the tear film as it helps keep the meibomian glands duct open so that they function optimally. Women who apply make-ups should also clean their make up thoroughly every night to avoid clogging the meibomian gland ducts.
Take frequent breaks while working on the computer. Apply the 20:20:20 rule. That is, for every 20 minutes of computer use, look at an objected situated 20 feet away and blink for 20 seconds.
Blink more often. This ensures the eyelids are lubricated and prevents evaporation of tears.
Use wrap-around eyewear. This protects the eye against harsh environmental conditions.
Consult your eye doctor if you experience dry eye with your medication. There may need to adjust or change your medications in this case
Discontinue contact lens wear or adjust the wearing schedule if you experience dry eyes due to contact lens wear
Avoid all occasions and environmental conditions that may cause dry eyes.