**Core Concept**
Type 1 diabetes is a chronic metabolic disorder characterized by absolute insulin deficiency, leading to hyperglycemia and potential long-term complications, including diabetic retinopathy. Early detection of retinopathy is crucial for preventing vision loss.

**Why the Correct Answer is Right**
Diabetic retinopathy is a common complication of diabetes, and its early detection is vital for preventing vision loss. The American Diabetes Association recommends performing a comprehensive eye examination by an ophthalmologist or optometrist 5 years after the onset of diabetes in children and adolescents, or within 3 years after the onset of diabetes if there are any signs of diabetic retinopathy. This is because the risk of developing diabetic retinopathy increases with the duration of diabetes.

**Why Each Wrong Option is Incorrect**
**Option A:** Immediate examination at the time of diagnosis is not recommended because the risk of retinopathy is low in the initial years after diagnosis.
**Option B:** Examination after 10 years is not advised because the risk of retinopathy increases with the duration of diabetes, and early detection is crucial for preventing vision loss.
**Option C:** Examination every 2 years is not recommended because the risk of retinopathy is not uniform, and more frequent examinations may not be necessary for all patients.

**Clinical Pearl / High-Yield Fact**
In children and adolescents with type 1 diabetes, the risk of developing diabetic retinopathy increases with the duration of diabetes, and early detection is crucial for preventing vision loss. A comprehensive eye examination by an ophthalmologist or optometrist should be performed 5 years after the onset of diabetes.

**Correct Answer:** C. 5 years after the onset of diabetes.