Interstitial Keratitis Overview

Interstitial Keratitis

• Interstitial keratitis is a condition characterized by ulcerating vascular inflammation of the cornea's stroma.
• It can lead to severe vision impairment and potential blindness.
• Treatment, if administered early and appropriately, can be effective.

Syphilitic Interstitial Keratitis

• Congenital syphilis is a possible etiology, accounting for a proportion of bilateral cases.
• Acquired syphilis, together with HSK (hypopyon-uveitis-keratitis), can also result in interstitial keratitis.
• Unilateral interstitial keratitis is often associated with acquired syphilis.
• Segmental involvement tends to be more likely in unilateral cases.

Interstitial Keratitis - Manifestations

• Posterior stromal scarring is a defining feature.
• Presence of blood vessels should be noted
• Distinction between superficial and deep blood vessel patterns is clinically significant.

IK Clinical Presentation

• Initial symptoms include pain, tearing, and photophobia, along with perilimbal injection.
• Early signs often include sectoral superior stromal inflammation and the presence of keratic precipitates (KP).
• Late signs might involve deep potassium vascularization, which can progress to intense corneal pink coloration.
• Eventually, keratic scarring, ghost vessels, vision loss (reduced visual acuity), and irregular astigmatism or stromal opacification may be observed.

Ghost Vessels

• Ghost vessels are characterized by the presence of clearer lines, revealing the locations of former blood vessels within the cornea.

Interstitial Keratitis and Syphilis

• Salmon patch (deep stromal neovascularization) is frequently observed in association with interstitial keratitis associated with syphilis.

Interstitial Keratitis - Other Characteristics

• Deep stromal scarring and ghost vessels are diagnostic features
• Cases involving seropositive adults and prior bilateral keratitis during childhood are examples

Congenital Syphilis Manifestations

• Dental deformities, including issues involving the CN VIII (vestibulocochlear) nerve.
• Bone and cartilage abnormalities present in the form of saddle nose, saber shins, and frontal bossing.
• Cognitive impairment is another potential complication.

Syphilitic Interstitial Keratitis Manifestations

• Most cases manifest within the first two years of a child's life. This can also be seen through a later onset of an immune-mediated manifestation in a later decade.

Other Causes of Interstitial Keratitis

• Rare but possible causes include mycobacterium tuberculosis, mycobacterium leprae, Borrelia burgdoferi (Lyme Disease), measles, Epstein-Barr virus (infectious mononucleosis), Chlamydia trachomatis, leishmaniasis, and onchocerciasis.

Onchocerciasis

• Onchocerca volvulus is a nematode that can cause blindness, targeting human hosts.
• Simulium blackfly is a vector.
• Treatment involves ivermectin every six months and potential adjunct doxycycline.

Cogan Syndrome

• Cogan syndrome is a rare autoimmune disorder affecting young adults
• The syndrome often includes stromal keratitis (treated with topical steroids), vertigo, hearing loss, and urgent treatment with oral prednisolone and a systemic vasculitis component (e.g. polyarteritis nodosa).