Superior Limbic Keratoconjunctivitis (SLK) Workup

Updated: Apr 06, 2023
  • Author: Jean Deschênes, MD, FRCSC; Chief Editor: Hampton Roy, Sr, MD  more...
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Approach Considerations

Superior limbic keratoconjunctivitis (SLK) has been associated with thyroid dysfunction; therefore, investigations into thyroid function, including thyroid-stimulating hormone (TSH), free thyroxine (T4), thyroid-stimulating immunoglobulin, or TSH–binding inhibitory immunoglobulin, may be appropriate. An endocrinologist consultation should be obtained to aid in this workup.

To evaluate for and/or rule out dry eye syndrome, which often is present with superior limbic keratoconjunctivitis (SLK), the Schirmer test, measurement of tear lake, and tear breakup time are used.

The diagnosis of superior limbic keratoconjunctivitis (SLK) is based on clinical findings. The following laboratory studies and tests should be considered:

  • Slit-lamp examination
  • Fluorescein and lissamine green staining or rose Bengal staining
  • Schirmer test
  • Examination for thyroid orbitopathy
  • Thyroid function test
  • Autoimmune markers (anti-Ro [SS-A] and anti-La [SS-B] antibodies and cyclic citrullinated-peptide antibodies)

Histologic Findings

Surgical specimens taken from patients with superior limbic keratoconjunctivitis (SLK) who had not received treatment with silver nitrate demonstrate abnormal limbic epithelium with keratinized epithelial cells with dyskeratosis and acanthosis and balloon degeneration of some nuclei. The intracellular accumulation of glycogen in the epithelial cells of tissue sections of the bulbar conjunctiva has been documented. The conjunctival stroma demonstrates edema without significant inflammatory cellular infiltrate. In specimens obtained after silver nitrate treatment, significant inflammatory cells, including plasma cells, neutrophils, and lymphocytes, are also found in the epithelium and stroma.

Immunohistochemical pathologic examination of the abnormal conjunctiva in superior limbic keratoconjunctivitis demonstrates a lack of the typical mosaic pattern of the epithelium in the resulting keratinized cells before the patient undergoes treatment and upregulation of transforming growth factor-beta 2 and tenascin. [14] In separate studies, increased expression of proliferating cell nuclear antigens and altered expression of cytokines, [15] as well as the presence of involucrin, [16] was shown. More recently, heightened levels of matrix metalloproteinases 1 and 3 have been detected in specimens with the clinical manifestations of SLK. [17]

In vivo laser scanning confocal microscopy has been used to aid in diagnosing and grading the severity of the unique manifestations of SLK. [18]  Significant infiltration of inflammatory cells and dendritic cells may be seen in the upper bulbar conjunctiva by in vivo confocal microscopy  [18] .