A 29 years old man with IDDM for the last 14 years develops sudden vision loss, has non–proliferating diabetic retinopathy, cause is –
**Core Concept**
Diabetic retinopathy is a microvascular complication of diabetes mellitus, characterized by damage to the blood vessels in the retina. Non-proliferative diabetic retinopathy (NPDR) is an early stage of diabetic retinopathy, where the blood vessels in the retina become fragile and prone to leakage.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of diabetic retinopathy. In NPDR, the fragile blood vessels in the retina can rupture, leading to a sudden vision loss. This is due to the accumulation of fluid and blood in the retina, causing macular edema. The macula is responsible for central vision, and its edema can lead to a sudden loss of vision.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because proliferative diabetic retinopathy (PDR) is a more advanced stage of diabetic retinopathy, characterized by the growth of new, fragile blood vessels. While PDR can also cause vision loss, it is not the primary cause in this scenario.
* **Option B:** This option is incorrect because diabetic nephropathy is a complication of diabetes mellitus that affects the kidneys, not the eyes.
* **Option C:** This option is incorrect because diabetic neuropathy is a complication of diabetes mellitus that affects the nerves, not the eyes.
**Clinical Pearl / High-Yield Fact**
In diabetic retinopathy, the presence of macular edema is a red flag for sudden vision loss. It is essential to perform a thorough eye examination, including optical coherence tomography (OCT), to diagnose and manage macular edema promptly.
**Correct Answer: C. Diabetic nephropathy.**