Keratoconjunctivitis sicca, also known as KCS, is a common condition in which the eyes do not produce enough tears or fail to retain a protective layer of moisture. Medical professionals sometimes refer to KCS as “dry eye syndrome”.

KCS can cause eye irritation and discomfort in the form of itching, burning, and grittiness. The condition can also affect a person’s vision since inadequate lubrication alters how light travels through the eyes and onto the retina.

This article describes KCS, including its symptoms. We also outline some risk factors for developing KCS and provide information on diagnosis and treatment.

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KCS, or dry eye syndrome, is a common, chronic disorder affecting tear production.

Tears consist of oil, meibum, and water. Together, these components help protect and nourish the eye’s surface. The oil prevents moisture evaporation, and the meibum allows the tear to spread evenly over the eyes’ surface. In KCS, a person does not produce enough tears, or their tears are of poor quality and lack oil or meibum.

Tears are essential to eye health. They have various functions, including:

  • lubricating the eyes
  • cleansing foreign matter from the surface of the eyes
  • reducing the risk of infection

KCS causes dryness of the conjunctiva and cornea. The conjunctiva is the membrane that covers the whites of the eyes and the inner eyelids. The cornea is the thin, protective layer that covers the iris and pupil.

The primary symptom people with KCS experience is eye irritation. The irritation may differ in type and severity from one person to the next.

Potential symptoms of KCS include:

  • eye inflammation and redness
  • a stinging or burning sensation in the eyes
  • a feeling of dryness or grittiness in the eyes
  • stringy mucus in or surrounding the eyes
  • waking up with the eyelids stuck together
  • difficulty keeping the eyes open
  • eye sensitivity to smoke, wind, or light
  • eyes that tear readily
  • blurred or double vision
  • tired eyes after reading
  • discomfort when wearing contact lenses

Living with KCS can be challenging. Individuals who experience chronic pain may develop anxiety or depression and withdraw from their usual daily activities. Those who experience visual problems may be unable to drive, read, or use a computer, which can lead to further frustration and a sense of hopelessness.

Certain causes and risk factors that increase a person’s likelihood of developing KCS include:

To diagnose KCS, an ophthalmologist or optometrist will perform a comprehensive eye examination that includes testing the quantity and quality of tear production.

The assessment may include:

  • Taking a medical history: This will help the doctor determine if the person has risk factors for KCS.
  • External examination: The doctor looks at the structure of the eye, including the eyelid and blink dynamics.
  • Eyelid and cornea evaluation: The doctor examines the eyelid and cornea using a bright light and magnification.
  • Testing the quantity and quality of tears: The doctor may use a special dye in the eyes to help them observe tear flow and identify any changes to the eyes’ surface caused by insufficient tears.

The overall aim of KCS treatment is to keep the person’s eyes lubricated and minimize dryness. However, the exact treatment path will vary according to the underlying cause.

Doctors use four approaches to keep the eyes lubricated. They are:

  • Using artificial tears: Over-the-counter artificial tears solutions are a first-line treatment for people with mild KCS. People should choose preservative-free solutions, as they contain fewer additives that can irritate the eyes.
  • Conserving tears: A doctor may block the tear ducts with removable silicone plugs or a permanent surgical procedure. Both methods slow down tear drainage, meaning the tears remain in the eyes for longer.
  • Increasing tear production: An optometrist or ophthalmologist may recommend methods for increasing tear production. Examples include taking prescription eye drops or taking omega-3 fatty acid supplements.
  • Treating inflammation and infection: An optometrist or ophthalmologist may recommend one or more of the following treatments for inflammation and infection of the eyelids or eye surfaces:

The medication cyclosporine or lifitegrast reduces eye inflammation and may increase tear production. Many people experience significant improvement in their KCS symptoms after taking cyclosporine eye drops.

In some cases, a doctor may recommend a type of contact lens called a scleral lens. This lens traps a reservoir of fluid behind it, which prevents the cornea from drying out and allows it to heal. A scleral lens is much larger than a standard contact lens. It covers the cornea as well as the sclera, which is the white part of the eye.

For most people, KCS is uncomfortable but does not cause complications.

However, severe KCS could lead to the following:

KCS may be a symptom of another health issue, so anyone who experiences eye problems should consult their doctor for a prompt and accurate diagnosis.

KCS is the medical term for dry eyes. Although KCS usually causes only mild discomfort, severe cases may result in permanent damage to the cornea. The primary symptoms are eye irritation in the form of burning, itchiness, or grittiness. Anyone who experiences symptoms should consult their doctor for a diagnosis and appropriate treatment.

Most treatments aim to promote eye lubrication but vary according to the cause of the condition and the severity of a person’s symptoms. A person may also receive medications to treat complications of KCS, such as eye inflammation and infection.