Excerpt from Keratitis, Interstitial

Synonyms, Key Words, and Related Terms: interstitial keratitis, syphilitic keratitis, Cogan syndrome, IK, syphilitic disease, syphilis, herpes

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Background: Interstitial keratitis (IK) is a broad, descriptive term that has become synonymous with syphilitic disease. Although syphilis remains the leading cause of IK, a various bacterial, viral, parasitic, and autoimmune causes of IK exist.

Pathophysiology: By definition, IK is a nonsuppurative inflammation, which is characterized by cellular infiltration of the corneal stroma. In general, no primary involvement of the corneal epithelium or endothelium occurs. Inflammation may be either the direct result of an infectious process or, more commonly, secondary to an immunologic response to a specific foreign antigen. This immunological response may take the form of antigen-antibody complex deposition, complement-mediated disease, or a delayed-type hypersensitivity reaction.

Frequency:

In the US: IK generally is seen in the context of syphilis and, less commonly, in the context of herpes and Cogan syndrome.

Internationally: In various countries in which mycobacterial diseases (eg, tuberculosis, leprosy) are endemic, these and other parasitic causes of IK may be seen with greater frequency.

Mortality/Morbidity: Ocular morbidity generally is in the form of corneal scarring, which can interfere with visual acuity.

Race: No known racial predilection exists.

Sex: No gender predilection exists.

Age: IK generally is a disease that manifests in the third to fifth decades of life.