## **Core Concept**
Corneal dystrophies are a group of inherited, bilateral, and progressive corneal disorders characterized by the accumulation of abnormal substances within the cornea. They typically follow an autosomal dominant pattern of inheritance. These conditions often present with specific corneal changes that can lead to visual impairment.

## **Why the Correct Answer is Right**
The correct answer, **D. Bilateral and symmetrical**, is right because corneal dystrophies characteristically affect both eyes and often present with symmetrical corneal changes. This symmetry is a hallmark feature that distinguishes dystrophies from other corneal pathologies, such as infections or injuries, which may affect one eye more than the other.

## **Why Each Wrong Option is Incorrect**
- **Option A: Unilateral** - This option is incorrect because corneal dystrophies are typically bilateral, affecting both eyes.
- **Option B: Infectious** - This option is incorrect because corneal dystrophies are not caused by infections; they are primarily genetic in nature.
- **Option C: Unrelated to genetics** - This option is incorrect because most corneal dystrophies have a strong genetic component, often inherited in an autosomal dominant manner.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that corneal dystrophies often have a specific age of onset and progression, and they can lead to significant visual impairment. Early diagnosis and understanding the genetic basis can help in family planning and in considering surgical interventions like corneal transplantation.

## **Correct Answer:** . Bilateral and symmetrical