## **Core Concept**
Trisomy 13, also known as Patau syndrome, is a genetic disorder caused by an extra copy of chromosome 13. It leads to severe intellectual disability and physical abnormalities. Ocular manifestations are common in Trisomy 13.

## **Why the Correct Answer is Right**
Microphthalmia, which refers to one or both eyes being abnormally small, is a characteristic ocular feature of Trisomy 13. This condition occurs due to abnormal development of the eye during embryogenesis. The presence of microphthalmia is often used as a diagnostic clue for Trisomy 13.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While other ocular abnormalities like retinal dysplasia and cataracts can occur, they are not as specifically characteristic of Trisomy 13 as microphthalmia.
- **Option B:** This option is not specified, but given that the correct answer is microphthalmia, any other option not describing microphthalmia would be incorrect.
- **Option C:** Similar to Option B, without specifics, we assume it's incorrect because it doesn't describe microphthalmia.
- **Option D:** This option is also not specified, but again, it's incorrect because microphthalmia is the correct answer.

## **Clinical Pearl / High-Yield Fact**
A key clinical correlation to remember is that Trisomy 13 often presents with a combination of severe intellectual disability, heart defects, and ocular abnormalities, with microphthalmia being a hallmark ocular finding.

## **Correct Answer:** D. Microphthalmia