Acute Phase
Critical
Marked corneal stromal blood vessels and edema.
Other
Anterior chamber cells and flare, fine keratic precipitates on the corneal endothelium, conjunctival injection.
Chronic Phase
(See Figure 4.17.1.)
Deep corneal haze or scarring, corneal stromal blood vessels containing minimal or no blood (ghost vessels), stromal thinning.
Most Common
HSV is the most common cause of IK (see 4.15, HERPES SIMPLEX VIRUS). Other common causes include: VZV, congenital syphilis (bilateral in 80% of cases, often occurs in the first or second decade of life, rare in first years of life. Affects both eyes within 1 year of each other, more commonly occurs as late inactive/immune-mediated disease and less often as acute/infectious disease), acquired syphilis, and tuberculosis (TB, unilateral and often sectoral).
Less Common
Epstein-Barr virus (EBV) Lyme disease, leprosy, and Cogan syndrome (autoimmune disorder characterized by bilateral IK, vertigo, tinnitus, hearing loss, and negative syphilis serologies; also associated with systemic vasculitis [e.g., polyarteritis nodosa] and typically occurs in young adults).
For active IK or old, previously untreated IK:
IK is broadly defined as any non-ulcerating inflammation of the corneal stroma without epithelial or endothelial involvement, but often with neovascularization. IK is the common end-point of many corneal diseases.