A swollen cornea, or corneal edema, occurs when fluid accumulates within the cornea, the transparent front part of the eye. This fluid buildup can cause the cornea to become cloudy or hazy, leading to blurred vision. Corneal edema is a symptom, indicating an underlying issue affecting the cornea’s delicate fluid balance.
Understanding the Cornea
The cornea serves as the eye’s clear, dome-shaped outer layer, focusing light onto the retina. Lacking blood vessels, it relies on tears and aqueous humor for oxygen and nutrients, maintaining its transparency. A specialized layer of cells on its innermost surface, the endothelium, actively pumps excess fluid out of the cornea, preventing swelling. When this endothelial pump function is compromised, fluid accumulates, leading to corneal swelling.
Infections and Inflammatory Conditions
Infections are a significant cause of corneal swelling, often leading to inflammation known as keratitis. Bacterial infections, for instance, can cause the cornea to swell and become opaque as immune cells combat invading microorganisms. Viral infections, particularly those caused by the herpes simplex virus, can also damage corneal cells, resulting in edema.
Fungal and parasitic infections, such as those caused by Acanthamoeba, are less common but can lead to severe and persistent corneal swelling. These infections often result in significant inflammation and tissue destruction, making the cornea unable to effectively manage its fluid content. Non-infectious inflammatory conditions like uveitis (inflammation inside the eye) or scleritis (inflammation of the white outer layer of the eye) can also affect the cornea. The inflammation in these conditions can disrupt the cornea’s normal physiology, contributing to fluid accumulation and swelling.
Trauma and Post-Surgical Swelling
Physical injuries to the eye can directly damage the cornea, leading to swelling. Blunt force trauma, such as a blow to the eye, can harm endothelial cells, impairing their ability to pump fluid. Foreign bodies embedded in the cornea can also cause localized swelling and inflammation.
Eye surgeries, especially intraocular procedures like cataract removal, are another common cause of corneal swelling. During cataract surgery, manipulation within the eye can temporarily or permanently damage endothelial cells. This damage reduces the cells’ fluid-pumping efficiency, leading to post-operative corneal edema. While temporary swelling is expected and typically resolves within a few weeks, persistent edema after surgery can indicate significant endothelial cell dysfunction.
Underlying Ocular Conditions
Certain chronic or genetic eye conditions can predispose individuals to corneal swelling. Fuchs’ Endothelial Dystrophy is a genetic disorder where endothelial cells progressively deteriorate. As these cells diminish in number and function, their ability to remove fluid from the cornea is compromised, leading to chronic fluid buildup and clouding.
Uncontrolled high intraocular pressure, a hallmark of glaucoma, can also stress the cornea and impair its clarity. Elevated pressure within the eye can disrupt the metabolic function of endothelial cells, reducing their efficiency in pumping fluid out of the cornea. This can result in corneal edema, particularly in acute or severe glaucoma.
Contact Lens-Related Issues
Improper contact lens use is a frequent cause of corneal swelling. Overwearing lenses, especially sleeping in lenses not designed for overnight use, can significantly reduce the oxygen supply to the cornea, a condition known as hypoxia. This oxygen deprivation disrupts metabolic processes, leading to fluid retention and swelling.
Poor contact lens hygiene or ill-fitting lenses can also contribute to corneal edema. Mechanical irritation from a poorly fitted lens or deposits on the lens surface can cause inflammation and disrupt the corneal epithelium. This irritation can impede the cornea’s natural fluid regulation, resulting in swelling.