First described by German ophthalmologist Dr. Albrecht von Gräfe, sclerosing keratitis is a type of interstitial keratitis that involves severe inflammation of the peripheral cornea and/or sclera near the cornea. Sclerosing keratitis can occur alone or as a complication of scleritis, resulting in corneal scarring and potentially impacting visual acuity depending upon its progression towards the visual axis.
Sclerosing keratitis has been associated with infection and autoimmunity;
- Infectious; i.e. Leprosy, tuberculosis, onchocerciasis, mumps
- Autoimmune; i.e. Granulomatosis with polyangiitis, rheumatoid arthritis
Females are affected more than males and the disease is often bilateral. Thorough discussion should take place with the patient about recent travel (such as to places with high rates of leprosy, TB, onchocerciasis, or mumps) as well as family history of autoimmune conditions to determine the etiology.
Similar to scleritis, sclerosing form is associated with ocular pain. Vision is not affected unless the opacity crosses the visual axis, in which case vision will become significantly blurry and poor. Patients will also commonly report epiphora, ocular redness, and photophobia.
Systemic signs can be associated with specific autoimmune disorders, but it is possible to have sclerosing keratitis due to autoimmunity without having systemic signs.
Sclerosing keratitis involves scleral inflammation invading the cornea, both by distance and depth, causing edema, opacification, as well as changes to the cornea which resemble sclera. The area of sclerosing is typically next to the inflamed area of sclera but will extend regardless of active scleritis. It must include the posterior layers of the cornea for diagnosis though it may also involve the anterior layers. Sclerosing can result in limbal guttering. Deposits exist in the stromal opacification that have been described as “candy floss” and “crystalline” in appearance. The opacification can be yellow or white/gray colored, waxy, and may develop a bordering precipitin ring.
Vascularization of the opacification is possible but infrequent, and this does not occur at the encroaching front of the opacity. It may be vascularized at any layer, though usually in the posterior layer. Rarely does vascularization reach the center of the cornea, typically only if longstanding and untreated.
- Inflammatory markers: CRP, ESR
- Autoantibody panel: ANA, ANCA, RF antibodies, anti-CCP antibodies
- TB skin test/QuantiFERON blood test
- Skin biopsies & cultures
- CBC w/ diff, CMP, UA
Treatment must address the cause of disease, either eliminating the source of infection or managing autoimmunity. Referral to rheumatology or infectious diseases should be done once the cause is determined so that an appropriate treatment plan can be initiated.
When the cause is treated and active inflammation resolves, corneal scarring will remain. This will not affect visual acuity unless it is in the visual axis. The visual axis is not commonly affected because the opacification begins on the periphery of the cornea and can be halted with early medical intervention. If the visual axis is affected by scarring, keratoplasty may be indicated.
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