Keratoconjunctivitis sicca (KCS), commonly known as dry eye syndrome, is a prevalent chronic eye condition characterized by either insufficient tear production or poor tear quality. This article explores KCS types not associated with Sjogren’s syndrome, an autoimmune disorder that primarily affects glands producing moisture. Understanding this specific condition, its common causes, diagnostic methods, and available non-Sjogren’s treatment options can help individuals manage their symptoms effectively.
What is Keratoconjunctivitis Sicca?
Tears are composed of three layers: an oily outer layer, a watery middle layer, and an inner mucus layer. The oily layer, produced by meibomian glands, helps prevent rapid tear evaporation. The watery layer, primarily from lacrimal glands, provides moisture and washes away debris. The mucus layer helps tears spread evenly across the eye’s surface. An imbalance in tear production or quality makes the tear film unstable, leading to KCS.
Individuals with KCS often experience uncomfortable symptoms. These include dryness, grittiness, or a foreign body sensation, along with burning, stinging, and redness. Light sensitivity and fluctuating blurred vision, which may temporarily improve with blinking, are also common. Severe irritation can sometimes lead to excessive watery eyes, as the eye attempts to compensate for underlying dryness.
Factors Contributing to KCS
Numerous factors can contribute to the development of KCS, particularly those not linked to Sjogren’s syndrome. Aging is a common factor, as tear production naturally declines with age, especially in postmenopausal women due to hormonal changes. Certain medications can also reduce tear or mucus production, including antihistamines, decongestants, antidepressants, diuretics, and some blood pressure medications like beta-blockers. Isotretinoin and antiandrogens are also known contributors to evaporative dry eye.
Environmental conditions play a significant role in KCS. Dry climates, low humidity, wind exposure, and smoke can increase tear evaporation and irritate the eye surface. Indoor factors like air conditioning and heating systems also reduce humidity, exacerbating symptoms. Prolonged screen time, such as using computers, tablets, or smartphones, leads to a reduced blink rate, causing tears to evaporate more quickly.
Contact lens wear is another common contributor to KCS, as lenses can disrupt the natural tear film, accelerate evaporation, and increase friction on the eye’s surface. This can lead to increased tear osmolarity and discomfort. Previous eye surgeries, particularly LASIK, can also induce KCS by temporarily damaging corneal nerves, which affects tear production signals to the brain. While symptoms often improve within 6 to 12 months post-LASIK, some individuals may experience chronic dry eye.
Beyond these factors, several systemic conditions not associated with Sjogren’s syndrome can also cause KCS. Diabetes can affect the delicate balance of tear production and drainage by damaging blood vessels and nerves. Thyroid disorders, such as Graves’ disease, can lead to bulging eyes and incomplete eyelid closure, increasing tear evaporation. Other conditions like rosacea and blepharitis can impact the meibomian glands, leading to evaporative dry eye.
Identifying KCS
Diagnosing KCS involves a comprehensive eye examination by an eye care professional. The process begins with a thorough review of the patient’s medical history to identify any contributing factors or underlying conditions. A slit-lamp examination allows the doctor to closely examine the ocular surface, tear film, and eyelids.
Several specific tests are commonly used to assess tear production and tear film stability. The Schirmer test measures tear production by placing a small strip of filter paper inside the lower eyelid for five minutes. A wetting of less than 5.5 mm in five minutes often indicates aqueous tear-deficient KCS. The tear breakup time (TBUT) test assesses tear film stability; a small amount of fluorescein dye is applied to the tear film, and the time until the first dry spot appears on the cornea after a complete blink is measured under a cobalt blue light. A TBUT of less than 10 seconds is considered abnormal.
Vital dye staining, using agents like fluorescein and lissamine green, helps identify damage to the eye surface. Fluorescein stains areas where corneal epithelial cells are loose or damaged, appearing bright green under blue light. Lissamine green stains damaged cells on the conjunctiva. These tests collectively help differentiate KCS from other eye conditions and confirm the diagnosis.
Treatment and Management Strategies
Management and treatment strategies for KCS aim to alleviate symptoms and improve the quality and quantity of tears. Initial approaches often involve over-the-counter options like artificial tears, gels, and ointments. Low-viscosity artificial tears are suitable for replacing tear volume, while more viscous options or those containing lipids can help reduce evaporation, particularly in evaporative KCS. Lubricating ointments applied at night can provide prolonged relief.
For persistent inflammation, prescription eye drops are often recommended. Cyclosporine ophthalmic emulsion, such as Restasis, increases tear production by reducing ocular inflammation. These drops may take several months to show a noticeable effect and can cause a stinging sensation. Another prescription option is lifitegrast ophthalmic solution, known as Xiidra, which works by blocking the interaction between specific cell surface proteins to reduce inflammation.
Procedural treatments can also help conserve natural tears. Punctal plugs are tiny, biocompatible devices inserted into the puncta, the small openings that drain tears from the eye, blocking tear drainage to keep tears on the eye’s surface longer. These can be temporary or semi-permanent. In cases where blepharitis is a contributing factor, specific lid hygiene practices are beneficial, including warm compresses, gentle eyelid massage, and cleaning the eyelid margins with diluted baby shampoo or commercial cleansers to improve meibomian gland function.
Lifestyle adjustments are also important for managing KCS. Using humidifiers can increase moisture in the air, especially in dry environments or during colder months when indoor heating is common. Taking regular breaks from screens, such as following the “20-20-20 rule” (looking 20 feet away for 20 seconds every 20 minutes), can help reduce eye strain and encourage more frequent blinking. Avoiding direct air drafts from fans or air conditioning, along with smoke, can also minimize tear evaporation. Some eye care professionals suggest considering omega-3 fatty acid supplements, which may improve tear composition and reduce inflammation.