a. Fungal keratitis
b. Congenital syphilis
c. Phlyctenular keratitis
It develop from host immune mechanisms to active infections or antigens within the stromal keratocytes.
Diseases known to cause interstitial keratitis include: congenital syphilis, herpes simplex, herpes zoster, Epstein-Barr, tuberculosis and leprosy.
Clinical manifestations: superficial stromal scarring, necrotizing stromal keratitis and disciform keratitis.
As the inflammation subsides, intracorneal blood vessels will regress and become nonperfused vascular channels, which are known as "ghost" vessels. These vessels can be readily visualized using slit lamp biomicroscopy and can become active if inflammation recurs.
Reference: Parsons’ disease of the Eye,20th ed.,p-198