Keratoconjunctivitis sicca (KCS) is the medical term for chronic dry eye, a common condition affecting the surface of the eye. It involves the dryness of the conjunctiva, the clear membrane lining the eyelids and covering the white part of the eye, and the cornea, the clear front surface of the eye. This condition arises when the eyes do not produce enough tears or when the tears produced are of poor quality, leading to insufficient lubrication of the eye’s surface.
Recognizing the Signs
Individuals experiencing KCS often report a persistent feeling of dryness, grittiness, or as if something is in the eye. Stinging or burning sensations are also common.
The eyes may appear red and inflamed due to irritation. Sensitivity to light, known as photophobia, is another frequent symptom, making bright environments uncomfortable. Vision can also be affected, often presenting as fluctuating blurred vision that may temporarily improve with blinking. In some instances, the eyes might paradoxically water excessively as a reflex response to severe irritation and dryness. Symptoms are often worsened by prolonged visual efforts like reading or computer use, and by dry, windy, or smoky environments.
Understanding the Causes
KCS develops from various factors that disrupt the healthy tear film, which normally consists of three layers: fatty oils, aqueous (watery) fluid, and mucus. Problems with any of these layers can lead to dry eyes. There are two primary types of KCS based on the underlying cause: aqueous-deficient dry eye and evaporative dry eye.
Aqueous-deficient dry eye occurs when the lacrimal glands do not produce enough watery tears to keep the eye’s surface adequately covered. This type is frequently associated with increased age. Certain medical conditions, such as autoimmune diseases like Sjögren’s syndrome, rheumatoid arthritis, or systemic lupus erythematosus, can also lead to insufficient tear production.
Evaporative dry eye, which is more common, results from tears evaporating too quickly, often due to poor tear quality. This can be caused by issues with the meibomian glands in the eyelids, which are responsible for secreting the oily layer that prevents rapid tear evaporation. Prolonged screen use, a reduced blink rate, and environmental factors such as wind, smoke, or dry climates can also contribute to increased tear evaporation. Additionally, certain medications, including antihistamines, decongestants, antidepressants, diuretics, beta-blockers, and some blood pressure medications, can either reduce tear production or affect tear composition, contributing to KCS.
Diagnosis and Management Options
Diagnosis
Diagnosing keratoconjunctivitis sicca involves a comprehensive eye examination and a review of the patient’s medical history. Eye care professionals use specific diagnostic tests to assess tear production and tear film stability. These tests are performed before any eye drops are instilled.
One common test is the Schirmer test, which measures the amount of tears produced. A small strip of filter paper is placed at the edge of the lower eyelid, and the amount of wetting on the strip is measured after five minutes. A wetting of less than 5.5 mm after five minutes can indicate aqueous tear-deficient KCS.
Another assessment is the tear breakup time (TBUT) test, which evaluates tear film stability. After a small amount of fluorescein dye is instilled into the eye, the patient is asked to refrain from blinking, and the time it takes for the first dry spots to appear on the cornea is observed under a blue light. A normal tear breakup time is greater than 8 to 10 seconds; a shorter time suggests an unstable tear film.
Vital dye staining, using dyes like fluorescein, lissamine green, or rose bengal, helps identify damage to the ocular surface. Fluorescein primarily stains damaged corneal epithelial cells, while lissamine green is effective for staining the conjunctiva. These dyes highlight areas where cells are missing, damaged, or altered, providing visual evidence of the condition.
Management Options
Management strategies for KCS aim to alleviate symptoms, improve tear film stability, and reduce inflammation. Over-the-counter artificial tears and lubricating eye drops are often the first line of treatment for mild to moderate cases. These products help to supplement the natural tear film and provide temporary relief.
For more persistent symptoms, prescription medications may be recommended. Anti-inflammatory eye drops, such as cyclosporine ophthalmic emulsion (e.g., Restasis) or lifitegrast (e.g., Xiidra), work by reducing inflammation in the eye, which in turn can help increase tear production. Corticosteroid eye drops may also be used for short periods to manage acute inflammation.
Punctal plugs offer a way to conserve the eye’s natural tears by blocking the tear drainage ducts (puncta) in the inner corners of the eyelids. These tiny, biocompatible devices act like stoppers, keeping tears on the eye’s surface for a longer duration.
Lifestyle adjustments also play a role in managing KCS. Using humidifiers, blinking more frequently, taking regular breaks during prolonged screen use, and avoiding environmental irritants like wind or smoke can significantly reduce symptoms.
For severe cases, specialized contact lenses, such as scleral lenses, can create a fluid-filled reservoir over the cornea, providing continuous hydration and protection. Surgical options, such as permanent punctal occlusion or salivary gland transplantation, may be considered to further address tear drainage or production.