Excerpt from Keratoconjunctivitis, Superior Limbic

Synonyms, Key Words, and Related Terms: SLK, superior limbic keratoconjunctivitis, superior limbic filamentary keratoconjunctivitis

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Background: This disorder is characterized as an inflammation of the superior bulbar conjunctiva with predominant involvement of the superior limbus, an adjacent epithelial keratitis, and a papillary hypertrophy of the upper tarsal conjunctiva. In 1963, Thygeson and Kimura described it as a chronic, localized, filamentary conjunctivitis. It was given its name, superior limbic keratoconjunctivitis (SLK), by Theodore, contemporaneously. Five years later, Tenzel and Corwin reported an association with thyroid abnormalities and SLK. A mimicking disorder has been encountered in soft contact lens wearers, typically with exposure to thimerosal-preserved solutions.

Pathophysiology: It is believed that SLK is present secondary to superior bulbar conjunctiva laxity, which induces inflammatory changes from mechanical soft tissue microtrauma. In settings where the physiological tolerance of mechanical forces on the delicate ocular surface is exceeded, chronic inflammation results in thickening of the conjunctiva and keratinization, which then is cyclical in perpetuating the inflammation. Eventually, a filamentary response may be induced on the affected cornea. Factors inducing conjunctiva laxity include thyroid eye disease, tight upper eyelids, and prominent globes. Immunochemical histopathologic examination of the abnormal conjunctiva in SLK lends credence to microtrauma being of most significance to the development of SLK.

Frequency:

In the US: The frequency of SLK has been found to be 3% in a cohort of Graves ophthalmopathy patients, but it is much lower in the general population.

Internationally: Unknown

Mortality/Morbidity: The natural history of the disorder is remission and eventual total resolution but only after a prolonged clinical course.

Race: No racial predilection exists.

Sex: Women are predominantly affected.

Age: Typically, middle-aged people are affected; however, this entity has been reported to occur in patients aged 4-81 years.