Superior limbic keratoconjunctivitis (SLK) is a chronic and recurring inflammatory condition affecting specific parts of the eye’s surface. “Superior” refers to the upper region of the eye, while “limbic” denotes the limbus, the transitional zone where the clear cornea meets the white sclera.
The term “kerato-” indicates involvement of the cornea, the transparent front part of the eye. “-Conjunctivitis” signifies inflammation of the conjunctiva, the clear membrane covering the white part of the eye and lining the inside of the eyelids.
Symptoms and Associated Conditions
Individuals with superior limbic keratoconjunctivitis often report a persistent foreign body sensation. This feeling can worsen with blinking, leading to significant discomfort. Redness, particularly in the upper part of the eye, is a common observation.
Light sensitivity (photophobia) and excessive tearing are frequently reported symptoms. Pain in the affected eye can also occur, and some individuals may notice mild blurring of vision. Symptoms of SLK can develop slowly, sometimes over several years.
SLK has a notable association with thyroid disorders, especially hyperthyroidism and Graves’ disease. While not everyone with SLK has a thyroid condition, it is a recognized risk factor and can sometimes be an initial indication of thyroid dysfunction. The condition is also seen more frequently in middle-aged females.
Causative Factors
The primary theory explaining superior limbic keratoconjunctivitis centers on mechanical stress and friction. Increased rubbing occurs between the superior tarsal conjunctiva, which lines the upper eyelid, and the superior bulbar conjunctiva, which covers the upper part of the eyeball. This repeated microtrauma contributes to the inflammatory process.
Several factors can intensify this friction. A tight upper eyelid can increase rubbing against the ocular surface. Similarly, a prominent eyeball (proptosis), often observed in individuals with thyroid eye disease, can lead to heightened mechanical irritation. Additionally, a redundancy or looseness of the superior bulbar conjunctiva (conjunctival chalasis) can further contribute to irritation with every blink.
Diagnostic Process
Diagnosing superior limbic keratoconjunctivitis involves a comprehensive eye examination by an ophthalmologist. A key component is a slit-lamp examination, allowing magnification to identify characteristic signs of inflammation. During this examination, the superior bulbar conjunctiva may appear thickened, loose, and hyperemic, with radialized blood vessels extending towards the limbus.
Vital dyes are an important diagnostic step. Dyes like Rose Bengal or Lissamine Green are applied to the eye, selectively staining damaged cells on the cornea and conjunctiva. In SLK, these dyes highlight tissue damage, especially in the superior bulbar conjunctiva near the limbus and superior cornea, often in a punctate pattern. Given the strong association with thyroid issues, the eye doctor may also recommend blood tests to assess thyroid function.
Treatment Approaches
Initial management for superior limbic keratoconjunctivitis begins with conservative measures aimed at reducing friction and providing lubrication. This includes frequent application of artificial tears; preservative-free formulations are often preferred. Lubricating ointments or gels can also provide prolonged relief by creating a smooth surface and reducing mechanical rubbing.
If conservative treatments are insufficient, medical therapies may be prescribed. Topical steroid eye drops can reduce inflammation. Other prescription options include mast cell stabilizers, which help prevent the release of inflammatory chemicals, and cyclosporine drops, an immunomodulator that helps control the underlying inflammatory response.
Procedural interventions are considered when drops alone do not provide adequate relief. A bandage contact lens can serve as a physical barrier, shielding the inflamed superior conjunctiva and cornea from eyelid friction. Another common procedure involves applying a dilute silver nitrate solution to the superior conjunctiva, which chemically cauterizes cells to promote healing and reduce inflammation.
For severe or persistent cases that do not respond to other treatments, surgical options may be explored. Conjunctival resection, where a small segment of the affected superior bulbar conjunctiva is removed, can eliminate redundant tissue and reduce friction. Another surgical approach is thermal cauterization, which uses heat to shrink and stabilize loose conjunctival tissue. These procedures are reserved for patients whose symptoms significantly impact their quality of life despite less invasive interventions.