**Core Concept**
Long-term use of corticosteroids is associated with the development of cataracts, a condition characterized by the clouding of the lens in the eye. This is due to the glucocorticoid-induced disruption of the normal lens homeostasis and metabolism. The steroid-induced cataract is a well-documented side effect of systemic or topical corticosteroid therapy.

**Why the Correct Answer is Right**
The glucocorticoids, such as prednisone and dexamethasone, induce the formation of cataracts by promoting the accumulation of sorbitol in the lens, leading to osmotic swelling and eventual opacity. This is mediated through the inhibition of the enzyme aldose reductase, which normally breaks down sorbitol. The resulting cataract is typically a posterior subcapsular cataract, which can progress to a more severe nuclear cataract over time.

**Why Each Wrong Option is Incorrect**
**Option A:** Digoxin is a cardiac glycoside used in the treatment of heart failure and atrial fibrillation, and it is not associated with cataract formation.

**Option B:** Chloroquine is an antimalarial medication that can cause retinal toxicity, but it is not directly linked to cataract formation.

**Option C:** Methotrexate is an antifolate chemotherapeutic agent used in the treatment of cancer and autoimmune diseases, and it is not commonly associated with cataract development.

**Clinical Pearl / High-Yield Fact**
To remember the corticosteroid-induced cataract, recall the "4 Ds": Diabetes, Dyslipidemia, Dexamethasone, and Disuse (immobilization). These factors all contribute to the development of steroid-induced cataracts.

**Correct Answer: C. Dexamethasone**