Hong Kong Ophthalmological Society

Tears are produced by the lacrimal gland and are secreted to maintain the eye in an physiological state. When tear secretion is inadequate or distributed unevenly on the ocular surface to maintain adequate lubrication, dry eye syndrome will occur.

The function of tears

The function of tears include:

lubricating the cornea of the eye
maintaining the optics of the eye
oxygenating the cornea
flushing debris and foreign bodies and
protecting the cornea against bacteria or virus through antibodies.

Components of tears

The tear film is composed of three layers:

The outermost oily layer is synthesized by oil glands near the eyelashes. The oil layer prevents the evaporation of tears from the cornea.
The middle aqueous layer is secreted from the lacrimal gland and is the main component of the tear film.
The inner mucous layer which is secreted by the conjunctiva enables an even distribution of tears on the cornea.

The symptoms of Dry Eye Syndrome

When the tear secretion is inadequate or unevenly distributed, the eyes may feel gritty. A foreign body or burning sensation may also be present. In severe cases, one may feel blurry vision.

The causes of Dry Eye Syndrome

Tear production will reduce as one ages. Post menopausal women may also complain of dry eyes due to the decreased hormonal circulation. Some patients with Sjogren's disease may also concurrently suffer from dry mouth and autoimmune diseases including rheumatoid arthritis. Prolonged usage of contact lenses, blepharitis and conjunctivitis may also cause dry eyes.

Diagnosis

An ophthalmologist can determine whether one suffers from dry eyes from slit lamp examination and commonly by a test known as Schirmer's test.

Treatment

The treatment of dry eyes includes the use of artificial lubricating eye drops or ointments. To prevent the evaporation of tears, protective goggles may also be used. During winter, the ambient humidity can be increased by the use of humidifiers. Punctal plugs can also be used by an ophthalmologist to occlude the drainage of tears.

Disclaimer: The content of this article is for reference only and does not serve diagnostic or treatment purposes nor does it serve as any recommendation towards the use of particular eye treatment products.