Spring catarrah is:
**Core Concept**
Spring catarrah is a colloquial term used to describe a type of conjunctivitis that occurs during the spring season. It is a form of allergic conjunctivitis, which is an overreaction of the immune system to environmental allergens.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of allergic conjunctivitis. This condition is caused by the release of histamine and other chemical mediators from mast cells in the conjunctiva, leading to increased vascular permeability, edema, and itching. The allergen, often tree pollen, enters the eye through the conjunctival sac and triggers an allergic reaction.
**Why Each Wrong Option is Incorrect**
**Option A:** Spring catarrah is not caused by a bacterial infection, as it is not an infectious process.
**Option B:** It is not a viral conjunctivitis, as it is not caused by a viral agent.
**Option C:** It is not a condition related to the cornea, as it primarily affects the conjunctiva.
**Clinical Pearl / High-Yield Fact**
Allergic conjunctivitis can be treated with antihistamines, mast cell stabilizers, and corticosteroids. Patients with seasonal allergic conjunctivitis should avoid exposure to the allergen, use protective eyewear, and consider immunotherapy.
**Correct Answer: D. Allergic conjunctivitis**