**Core Concept**
Topical sodium cromoglycate is a mast cell stabilizer that prevents the release of histamine and other mediators from mast cells, thereby reducing inflammation and allergic reactions in the eye.

**Why the Correct Answer is Right**
Topical sodium cromoglycate works by inhibiting the release of histamine and other chemical mediators from mast cells, which are involved in the allergic response. It does not have any significant effect on histamine release once it has occurred, making it an effective treatment for allergic conjunctivitis and other ocular allergies. Sodium cromoglycate also has a mild anti-inflammatory effect, which further contributes to its therapeutic efficacy.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because sodium cromoglycate is not primarily used as an antihistamine. While it may have some antihistaminic effects, its primary mechanism of action is as a mast cell stabilizer.
**Option B:** This option is incorrect because sodium cromoglycate is not a corticosteroid. Corticosteroids are potent anti-inflammatory agents that work by suppressing the immune response, whereas sodium cromoglycate works by stabilizing mast cells and preventing the release of histamine.
**Option C:** This option is incorrect because sodium cromoglycate is not primarily used as an antibacterial agent. While it may have some antimicrobial properties, its primary use is as an anti-allergic agent.

**Clinical Pearl / High-Yield Fact**
Sodium cromoglycate is often used in combination with antihistamines or corticosteroids to provide a synergistic effect in the treatment of ocular allergies.

**Correct Answer:** C. Allergic conjunctivitis