**Core Concept:** Schik's test is a diagnostic test used to differentiate between primary glaucoma (POAG) and secondary glaucoma due to inflammation (inflammatory glaucoma). It involves measuring the intraocular pressure (IOP) after instilling a drop of pilocarpine 2% in each eye. In primary glaucoma, the IOP elevation remains the same or decreases after pilocarpine application, indicating normal miotic response. In inflammatory glaucoma, the IOP elevates due to miotic response inhibition, indicating an underlying inflammatory process.

**Why the Correct Answer is Right:** Schik's test helps differentiate between primary glaucoma and inflammatory glaucoma by assessing the miotic response to pilocarpine. In primary glaucoma, the miotic response is normal, leading to either no change or a decrease in intraocular pressure. However, in inflammatory glaucoma, the miotic response is inhibited, resulting in an increased intraocular pressure after pilocarpine application.

**Why Each Wrong Option is Incorrect:**

A. This option is incorrect because the miotic response is normal in primary glaucoma, leading to either no change or decreased IOP after pilocarpine application.

B. This option is incorrect because the miotic response is normal in primary glaucoma, leading to either no change or decreased IOP after pilocarpine application.

C. This option is incorrect because the miotic response is normal in primary glaucoma, leading to either no change or decreased IOP after pilocarpine application.

D. This option is incorrect because the miotic response is normal in primary glaucoma, leading to either no change or decreased IOP after pilocarpine application.

**Clinical Pearl:** Schik's test is a valuable diagnostic tool in differentiating primary glaucoma from secondary glaucoma due to inflammation, as it assesses the miotic response to pilocarpine. A normal miotic response (no change or decreased IOP) in Schik's test supports the diagnosis of primary glaucoma, while an elevated IOP after pilocarpine application is indicative of an underlying inflammatory process.