Dry Eye Syndrome

What is dry eye syndrome?

Dry eye syndrome (DES), also called dry eye or keratoconjunctivitis sicca (KCS), is a very common condition that is characterised by a disturbance of the tear film. This abnormality may result in disruption of the ocular surface, causing a variety of symptoms and signs and interference with quality of life.  Another term used for dry eye is ocular surface disease.

Dry eye syndrome is a common disorder of the normal tear film that results from decreased tear production, excessive tear evaporation, an abnormality in the production of mucus or lipids normally found in the tear layer, or a combination of these.

What causes dry eye syndrome?

Aqueous (watery) tear deficiency is caused by either poor production of watery tears or excessive evaporation of the watery tear layer. Poor production of tears by the tear glands may be a result of age, hormonal changes, or various autoimmune diseases, such as primary Sjögren’s syndrome, rheumatoid arthritis, or lupus. Evaporative loss of the watery tear layer is usually a result of an insufficient overlying lipid layer.

Some medications, such as antihistamines, antidepressants, beta-blockers, and oral contraceptives, may decrease tear production.

If blinking is decreased or if the eyelids cannot be closed, the eyes may dry out because of tear evaporation. While reading, watching TV, or performing a task that requires close attention with the eyes, a person may not blink as often. This decreased blinking allows excessive evaporation of the tears. Certain conditions, such as stroke or Bell’s palsy, make it difficult to close the eyes. As a result, the eyes may become dry from tear evaporation.

Abnormal production of mucin by the conjunctiva may occur. This can result from chemical (alkali) burns to the eye or because of different autoimmune diseases, such as Stevens-Johnson syndrome and cicatricial pemphigoid. This abnormal production leads to poor spreading of the tears over the surface of the eye. The surface of the eye can dry out and even become damaged, even though more than enough watery tears may be present.

Insufficient lipid layers are the result of meibomian gland dysfunction, rosacea, or following oral isotretinoin medication. Meibomian glands are the oil glands in the eyelids that produce the lipid layer. If these oil glands become blocked or if the oil is too thick, there may not be enough oil to cover the watery tear layer to prevent its evaporation.

In addition, if an infection is present along the eyelids or the eyelashes (called blepharitis) the bacteria may break down the oil, so there may not be enough oil. This may lead to evaporative loss of tears and dry eyes.

Between 50%-75% of contact lens wearers experience dry eyes at some point with many discontinuing or limiting lens wear because of this. Dry eye is a significant finding in patients having undergone refractive surgery, especially LASIK.

In addition to affecting ocular health, the discomfort and irritation of dry eyes can cause deterioration of general wellbeing, emotional health, and social functioning. Studies have demonstrated that people with dry eye syndrome are three times more likely than those without dry eyes to have difficulty with reading, computer work, watching TV, and driving.

What are dry eye syndrome symptoms and signs?

A person with dry eye syndrome may experience dry, gritty/scratchy, or a filmy feeling, burning or itching, redness of the eyes (conjunctivitis), blurred vision, foreign body sensation, and light sensitivity.

Symptoms seem to worsen in dry or windy climates and with higher temperatures and lower humidity. Symptoms may also be worse with prolonged use of the eyes (e.g. while reading and watching TV) and toward the end of the day.

Sometimes a symptom of dry eye syndrome may actually be intermittent excessive tearing. With dry eye, when the eyes becomes slightly dry and irritated, it may initiate reflex tearing with the production of a large amount of tears all at once to try to get moist and comfortable again. Unfortunately, the eyes can only handle so many tears at any one time; the rest pour over the eyelids and down the cheeks. Those tears that pour down the cheeks do not help the eyes and are wasted. A short time later, the eyes will become slightly dry and irritated again and the whole process may repeat itself.

During an eye examination, Dr Joseph will most likely be able to diagnose dry eye syndrome just by hearing the patient’s complaints about his or her eyes. Confirmation of the diagnosis can be made by seeing signs of dry eyes. As part of the eye examination, the following tests may be performed:

  • The front of the eyes is examined using a special microscope, called a slit lamp.
  • The amount and thickness of the tear film are inspected.
  • The stability of the tear film is assessed by checking the tear breakup time.
  • The conjunctiva is examined to determine if it is too dry.
  • The cornea is checked to see if it has dried out or become damaged.

Different dyes may be used during your eye examination. These are placed into the tears in the form of a drop. Fluorescein is a yellow dye that stains the cornea where epithelial (surface) cells have been worn away because of the lack of an adequate protective tear film. Rose Bengal is a red dye that stains the cornea and the conjunctiva where the cells are dead or dying as well as where healthy cells are inadequately protected by the tear film. Lissamine Green is a green dye which can help differentiate between normal and abnormal surface cells of the cornea and conjunctiva.

Schirmer tests measure the amount of tears produced by the eyes. The ophthalmologist places the end of a thin strip of filter paper just inside the lower eyelid. After a minute, the filter paper is removed and the amount of wetting is measured. Less wetting of the filter paper is more indicative of dry eye syndrome.

The osmolarity (salt content) of the tears may be measured. This is a new test which has been developed to aid in the diagnosis of dry eye syndrome, in which tear osmolarity is increased over normal levels.

If autoimmune diseases or Sjögren’s syndrome are suspected as a cause of dry eye syndrome, blood tests may be performed. These blood tests check for the presence of different autoantibodies that may be associated with dry eye syndrome.

Rarely a biopsy of the salivary glands may be performed. Certain disease processes, such as Sjögren’s syndrome, affect both the salivary glands, which produce saliva in your mouth, and the lacrimal glands, which produce tears.

Most people with dry eye syndrome have nothing to worry about aside from an annoying inconvenience. Although the symptoms might make activities of daily living (e.g., reading, watching TV, driving) miserable, no long-term vision loss is to be expected.

For those with more severe dry eye syndrome, significant drying of the surface of the eye can lead to an increased risk of serious infections. Ultimately, scarring, thinning, and even perforation of the cornea may occur. As a result, vision, or even the eye itself, may be permanently lost.

What are the risk factors for dry eye syndrome?

Dry eye syndrome is more common with increasing age, female sex, and Asian ethnicity. Menopause can increase the risk of dry eye syndrome. Paradoxically, postmenopausal women on hormone replacement therapy, especially estrogens alone, have a higher prevalence of dry eyes than postmenopausal women taking no hormones.

Occupational and environmental factors increasing risk include low humidity, high room temperature, wind exposure, pollution and poor air quality, smoking, and decreased blink rates due to sustained computer use or reading.

Diseases associated with dry eyes include vitamin A deficiency, autoimmune/connective tissue disease, hepatitis C infection, HIV infection, Sjögren’s syndrome, sarcoidosis, diabetes mellitus, and androgen or estrogen deficiency.

Contact lens wear increases the risk of dry eye syndrome. Refractive surgery, especially LASIK, frequently causes dry eyes.

A diet low in omega-3 fatty acids or a diet with a relatively high amount of omega-6 fatty acids relative to omega-3 fatty acids can also increase the risk of dry eye syndrome.

Various medications including systemic chemotherapy, diuretics, antidepressants, antihistamines and beta-adrenergic blockers may cause dry eyes as a side effect of the medication.

Irregularities of the conjunctival surface as seen with pingueculae or pterygia, can cause dry eye symptoms.


What is the medical treatment for dry eye syndrome?

Although no cure exists for dry eye syndrome, many treatments are available. Treatment is dependent on the severity of dry eye syndrome; some people may only require a humidifier or occasional eye drops while others may require surgery to help decrease dry eyes.

What medications are used to treat dry eye syndrome?

Certain prescription medications may help with dry eye syndrome.First line therapy includes the use of lubricants like Optive/Optive plus or Systane Ultra, 1 drop 4 times per day. Artificial tear insert may also be used. The insert is similar to a contact lens and is inserted 1-2 times per day. Cellulose is contained in the insert and acts to stabilise and thicken the film of tears over the eyes and to prolong the time the tear film works. The artificial tear insert must be properly inserted, otherwise corneal abrasion may occur.

Ideally one needs to target the cause of the dry eye,be it blepharitis, poor tear production, evaporation or a systemic disorder.

For more severe dry eye diseases, usually related to systemic disorders, then one can consider topical steroid therapy, and eventually immunosuppressant therapy.

Can surgery treat dry eye syndrome?

Different minor surgical procedures may help decrease dry eye syndrome. Near the inner corner of each eyelid are small openings, called punctae, that are the beginning of the normal tear drainage system. Punctal occlusion helps by decreasing the normal drainage of the tears from the ocular surface and down the tear drainage system, into the back of the nose, and down the throat. This occlusion is usually a very simple office procedure and only takes a few minutes.

Different punctal plugs or lacrimal canalicular plugs can be placed at or just inside these openings to block the normal drainage of tears down the tear drainage system. Just like a stopper placed in the drain of a sink keeps the water from flowing down the drain, these plugs keep the tears from flowing down the tear drainage system. Therefore, the eyes stay more moist and comfortable, even if one has fewer tears. These plugs can usually be removed very easily, if necessary. Sometimes, in severe cases of dry eye syndrome, these openings are permanently closed, usually by cautery (burning) or laser. This accomplishes the same thing as the plugs, but it is very difficult, if not impossible, to reverse.

If a person has difficulty closing the eyes for any reason, such as Bell’s palsy, the eyes may dry out because of tear evaporation. Lateral tarsorrhaphy is a procedure during which the lateral (outside) one-third of the eyelids are sewn together to decrease the ability of the eye to open widely and to help the eyes close more easily. If stroke or nerve damage keeps the eyelids from closing properly, a small gold weight may be implanted into the upper eyelid to help it close.