Nlicroaneu ‘lestation ofdiabetic retii6;patily. Which uf Ling layer isinvolved in diabetic etinopathv?
**Core Concept**
The question pertains to the pathophysiology of diabetic retinopathy, a microvascular complication of diabetes mellitus. The disease process involves changes in the retinal vasculature, leading to damage to the blood-retinal barrier and subsequent vision loss.
**Why the Correct Answer is Right**
Diabetic retinopathy primarily affects the innermost layer of the retina, the **inner limiting membrane**. This layer is composed of a basal lamina, a layer of retinal Müller cells, and a layer of astrocytes. The inner limiting membrane is involved in the disease process due to its role in maintaining the integrity of the blood-retinal barrier. Hyperglycemia leads to the activation of protein kinase C (PKC), which increases the permeability of the blood-retinal barrier, resulting in fluid leakage and edema.
**Why Each Wrong Option is Incorrect**
* **Option A:** The **retinal pigment epithelium (RPE)** is involved in the photoreceptor renewal and is not directly implicated in diabetic retinopathy.
* **Option B:** The **optic nerve** is a structure that transmits visual information from the retina to the brain, but it is not a layer involved in diabetic retinopathy.
* **Option C:** The **choroid** is a vascular layer between the sclera and the retina, but it is not the primary site of pathology in diabetic retinopathy.
**Clinical Pearl / High-Yield Fact**
The early signs of diabetic retinopathy include microaneurysms, retinal hemorrhages, and hard exudates. These changes can be visualized using fundoscopic examination or optical coherence tomography (OCT).
**Correct Answer:** C.