**Question:** Topical mitomycin C is used in the treatment of -

A. Keratitis
B. Corneal ulcer
C. Pterygium
D. Corneal ectasia

**Correct Answer:** D. Corneal ectasia

**Core Concept:**
Mitomycin C is a chemotherapeutic agent and alkylating agent, primarily used to treat various types of cancer. However, it has also been employed as an immunosuppressive agent in ophthalmology. Topical mitomycin C is used to prevent the formation of new blood vessels in the cornea, which is essential in the treatment of corneal ectasia (keratoconus and pachymeningitis) and corneal transplantation.

**Why the Correct Answer is Right:**
Mitomycin C works by inhibiting DNA synthesis in rapidly dividing cells, thereby suppressing neovascularization and immune response. In the context of corneal ectasia, topical mitomycin C is used to reduce the formation of new blood vessels in the cornea, which is crucial for the prevention of disease progression and graft survival in corneal transplantation.

**Why Each Wrong Option is Incorrect:**

A. Keratitis: Mitomycin C is not specifically targeted for treating keratitis. While it may have some effect, its primary use lies in preventing corneal ectasia and enhancing graft survival in corneal transplantation.

B. Corneal ulcer: While mitomycin C has some anti-inflammatory and antimicrobial properties, its primary use is for preventing corneal ectasia and enhancing graft survival in corneal transplantation, not treating corneal ulcers.

C. Pterygium: Pterygium is a benign conjunctival growth that does not involve neovascularization and requires surgical excision for management. Mitomycin C is not indicated in pterygium treatment.

**Clinical Pearl:**
In summary, mitomycin C is primarily used in corneal transplantation and corneal ectasia (keratoconus) management to prevent neovascularization and enhance graft survival. Its use in treating keratitis, corneal ulcers, and pterygium is limited and not its primary indication. Always consider the specific condition and its underlying pathophysiology when interpreting the clinical application of drugs like mitomycin C.