## **Core Concept**
The question tests knowledge on the complications associated with renal transplantation, specifically focusing on ocular complications. Renal transplantation is a major surgery that involves replacing a diseased kidney with a healthy one from a donor. Post-transplantation, patients are immunosuppressed to prevent organ rejection, which can lead to various complications, including ocular issues.

## **Why the Correct Answer is Right**
The correct answer, **C. Cytomegalovirus (CMV) retinitis**, is a well-recognized complication in immunocompromised patients, including those who have undergone renal transplantation. CMV retinitis is a sight-threatening infection that can cause retinal necrosis, hemorrhage, and detachment. The immunosuppressed state of transplant patients makes them susceptible to reactivation of latent CMV infection or primary infection, leading to CMV retinitis.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although cataracts can occur in the context of renal transplantation, they are not the most common ocular complication directly associated with the transplant process itself. Cataracts can be related to the surgery, steroids used for immunosuppression, or pre-existing conditions.
- **Option B:** This option is incorrect as it does not specify a known ocular complication directly linked to renal transplantation. Without a specific condition listed, it's hard to directly refute, but it's less directly related compared to CMV retinitis.
- **Option D:** This option is incorrect because, while various ocular surface disorders can occur in transplant patients, they are not as directly and commonly associated with the immunosuppressed state following renal transplantation as CMV retinitis.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that CMV retinitis is a significant ocular complication in immunocompromised patients, including those with renal transplants. Early recognition and treatment are crucial to prevent vision loss. CMV retinitis typically presents with retinal hemorrhages, exudates, and necrosis.

## **Correct Answer:** . **C. Cytomegalovirus (CMV) retinitis**