What causes corneal edema in the eye?

Corneal edema occurs when there is an accumulation of fluid within the corneal tissue, leading to a loss of transparency that can adversely affect vision. The primary mechanism behind this condition involves the disruption of the corneal epithelium, which serves as a barrier to prevent excessive fluid entry.

When the corneal epithelium is compromised due to injury, disease, or other factors, it can no longer effectively control the passage of water into the corneal stroma. This results in an imbalance, allowing water to enter the cornea, causing it to swell and lose its normal clarity.

While increased intraocular pressure can also lead to corneal changes, it is not the direct cause of edema in the same way that epithelial disruption is. Other factors such as conjunctival inflammation or corneal neovascularization may affect the eye but are not responsible for fluid accumulation in the cornea itself. Thus, the correct answer clearly highlights the central role of epithelial integrity in maintaining corneal transparency and preventing edema.