Amaurosisfugax is due to –
**Core Concept**
Amaurosis fugax is a transient, unilateral loss of vision in one eye, often described as a curtain or shade descending over the visual field. This condition is typically caused by a temporary reduction in blood flow to the retina.
**Why the Correct Answer is Right**
Amaurosis fugax is usually due to a temporary embolus or thrombus in the ophthalmic artery or its branches, which reduces blood flow to the retina. The embolus or thrombus may originate from atherosclerotic plaques in the carotid arteries or from cardiac sources such as atrial fibrillation. The reduced blood flow leads to a decrease in oxygen delivery to the retina, causing a temporary loss of vision.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because amaurosis fugax is not typically caused by a retinal detachment, which would be a more severe and chronic condition.
* **Option B:** This option is incorrect because migraines with aura can cause transient visual disturbances, but they are not the primary cause of amaurosis fugax.
* **Option C:** This option is incorrect because diabetic retinopathy can cause vision loss, but it is a chronic condition that does not typically present as a sudden, transient loss of vision.
**Clinical Pearl / High-Yield Fact**
Amaurosis fugax is often a warning sign for a more serious condition, such as a carotid artery stenosis or cardiac embolism. Patients with a history of amaurosis fugax should undergo a thorough evaluation of their cardiovascular system to identify and treat any underlying conditions.
**Correct Answer:** D.