**Core Concept**
Cornea verticillata is a well-known side effect of amiodarone, caused by accumulation of iodine in the corneal stroma, leading to characteristic whorl-like opacities. It is a sign of drug-induced toxicity and typically occurs in patients on long-term amiodarone therapy.

**Why the Correct Answer is Right**
Amiodarone contains a high concentration of iodine, which can deposit in the cornea and cause corneal deposits known as cornea verticillata. This finding is a marker of iodine toxicity and is reversible upon discontinuation of the drug. While corneal changes may be visible, they are generally asymptomatic and do not require surgical intervention. Stopping amiodarone allows the body to clear the iodine, and corneal deposits often resolve over time.

**Why Each Wrong Option is Incorrect**
Option B: Penetrating keratoplasty is a full-thickness corneal transplant, used only in severe, progressive corneal disease with significant vision loss. Cornea verticillata is not associated with such severe pathology and does not warrant surgery.
Option C: Lamellar keratoplasty is used for partial-thickness corneal defects, not for iodine-induced opacities. It is an invasive and rarely needed intervention in this context.
Option D: Observation is inappropriate because cornea verticillata is a sign of drug toxicity and may progress or be associated with other systemic effects. Continued use of amiodarone increases risk of other toxicities (e.g., pulmonary, hepatic).

**Clinical Pearl / High-Yield Fact**
Cornea verticillata is a reversible, drug-specific side effect of amiodarone. Its presence mandates immediate discontinuation of the drug, even if the patient is stable otherwise. It is a classic example of a drug whose toxicity should be recognized early to prevent irreversible complications.

✓ Correct Answer: A. Stop the drug