Following are the causes of painless sudden onset of loss of vision except –
**Core Concept**
The question is testing the student's knowledge of the causes of painless sudden onset of loss of vision, a symptom that requires a prompt and accurate diagnosis to prevent permanent vision loss.
**Why the Correct Answer is Right**
Painless sudden onset of loss of vision can be caused by several conditions, including ischemic optic neuropathy (ION), which occurs when the blood supply to the optic nerve is interrupted, leading to ischemia and subsequent vision loss. This can be due to various factors such as giant cell arteritis, non-arteritic anterior ischemic optic neuropathy (NAION), or other conditions that affect the blood supply to the optic nerve. The other causes of painless sudden onset of loss of vision include central retinal artery occlusion, central retinal vein occlusion, and optic neuritis.
**Why Each Wrong Option is Incorrect**
**Option A:**
* Not a recognized cause of painless sudden onset of loss of vision.
* Could be a distractor related to traumatic causes of vision loss.
**Option B:**
* Not a primary cause of painless sudden onset of loss of vision.
* Could be a distractor related to secondary causes of vision loss, such as diabetic retinopathy.
**Option C:**
* Not a recognized cause of painless sudden onset of loss of vision.
* Could be a distractor related to systemic conditions that affect vision.
**Option D:**
* Not a primary cause of painless sudden onset of loss of vision.
* Could be a distractor related to traumatic causes of vision loss.
**Clinical Pearl / High-Yield Fact**
Remember the "4 A's" of ischemic optic neuropathy: Age, Arterial disease, Arterial stenosis, and Anterior ischemia. This mnemonic can help you remember the key risk factors and pathophysiology of ION.
**Correct Answer:** D.