What is a key pathological mechanism leading to macular edema in retinal vein occlusion?

The key pathological mechanism leading to macular edema in retinal vein occlusion is increased vascular permeability. When a retinal vein becomes occluded, it creates a disruption in normal blood flow, resulting in increased pressure within the affected vein. This increased pressure leads to the leakage of fluid and proteins from the blood vessels into the surrounding retinal tissue, particularly affecting the macula, which is the area responsible for sharp, central vision.

As fluid accumulates in the macula, it causes the retinal tissue to swell, leading to macular edema. This condition is characterized by vision impairment and is one of the most significant complications that can arise from retinal vein occlusion. Understanding this mechanism is crucial for managing and treating patients with this condition, as therapies may focus on reducing vascular permeability or addressing the underlying causes of the occlusion.

Other mechanisms mentioned, such as increased intraocular pressure or decreased retinal perfusion, may occur in different contexts related to ocular diseases, but they are not the primary drivers of macular edema in retinal vein occlusion. Similarly, while retinal nerve damage can happen as a result of various conditions, it is the alteration in vascular permeability that specifically leads to the accumulation of fluid in the macula, resulting in edema.