## **Core Concept**
The question presents a clinical scenario involving a child with specific ocular symptoms, including lid lag, an enlarged cornea, and double contoured opacities concentric to the limbus. The key concepts here involve understanding the signs and symptoms associated with congenital glaucoma and other ocular conditions that could present similarly.

## **Why the Correct Answer is Right**
The correct answer, congenital glaucoma, is supported by the symptoms described:
- **Lid lag** can be associated with several conditions but in the context of other symptoms points towards increased intraocular pressure (IOP) which can cause mechanical difficulties.
- An **enlarged cornea** (diameter of 13mm) is a significant clue; the normal corneal diameter in infants is about 10-11 mm, so a diameter of 13mm suggests increased intraocular pressure leading to corneal stretching.
- **Double contoured opacities concentric to the limbus** are likely Haab's striae, which are characteristic horizontal or double contoured breaks in Descemet's membrane seen in congenital glaucoma due to the increased IOP.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although it might present with ocular symptoms, the specific combination of lid lag, enlarged cornea, and Haab's striae is most indicative of congenital glaucoma, not conditions typically associated with this option.
- **Option B:** Similarly, this option does not align well with the described symptoms of congenital glaucoma. Other conditions might present with some overlapping symptoms but not the classic triad suggestive of congenital glaucoma.
- **Option D:** This option is incorrect because it does not match the clinical presentation provided. Conditions under this option might have some similar symptoms but would not typically cause the specific findings of congenital glaucoma.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that **Haab's striae** are pathognomonic for congenital glaucoma. These are breaks in Descemet's membrane and are a critical diagnostic feature. The presence of an enlarged cornea and Haab's striae in a child should immediately suggest congenital glaucoma, prompting urgent ophthalmological evaluation to prevent vision loss.

## **Correct Answer: C.**