A corneal abrasion is a scratch or cut specifically on the cornea, the clear lens at the front of the eyeball. A corneal abrasion can be minor, lasting less than a day, or cause serious damage to the visual system. Here’s a look at the symptoms of a corneal abrasion.
What is the Cornea?
The main functions of the cornea are to protect the eye from injury or infection and to focus light as it is sent through the eyeball to the retina, located near the back, and then on to the brain. The cornea is composed of five layers:
- Epithelium: The epithelium is composed of thousands of nerve cells and is responsible for deflecting dirt, bacteria, and other particles, as well as absorbing nutrients and oxygen provided by tears for the whole cornea.
- Bowman’s Membrane: Composed of protein fibers called “collagen,” this membrane is easily scarred, which can potentially cause vision damage.
- Stroma: The stroma is a thick, transparent membrane made up of collagen and water and is the key in the cornea’s function of light passage.
- Descemet’s Membrane: This is an inner protective barrier composed of its own unique collagen. The cells are provided by the endothelium and it is easily repairable following injury.
- Endothelium: The endothelium is the innermost layer responsible for keeping extra water from building up in the stroma and its cells are irreparable when damaged or diseased.
The layers of the cornea are delicately balanced and extremely interdependent, just like the rest of the eyeball. The nerve cells in the epithelium mean scratching the cornea can be extremely painful; this is likely an evolutionary tactic of ensuring human’s are aware of any injury to the eye, because they are so vital to survival. While a light abrasion can heal within a day, more serious injuries can take closer to a week to heal. During this time, the eye is much more susceptible to infection, which can cause ongoing vision problems.
What Are the Symptoms of Corneal Abrasion?
Understanding how the cornea is composed and what it does can help symptoms make more sense. Corneal abrasions are often painful, consisting of an eyeball that seems to burn, sting, or produce the sensation that there is something lodged in your eye. This can be because of the abraded tissue or because there really is something still in the eye. The eyeball may have a red appearance, ranging from a slight discoloration to a completely bright red surface. This irritation may spread to the surrounding tissue, causing inflammation of the eyelids. Additionally, you may notice a slight twitching of the eye and increased tear production as the eye becomes more watery than normal. Visually, depending upon the placement of the abrasion, vision may become blurry. You may notice some photosensitivity (sensitivity to light). The extra stress on the eyeballs may also cause a headache and even nausea.
What Are Corneal Abrasion Complications?
Corneal erosion can occur when the newly formed cells fail to adhere to the epithelium as firmly as the original. This makes the area of healing easy to re-abrade. Something as gentle as blinking can disrupt the delicate new cells, ripping them back off and reopening the wound -- generally with just as much discomfort. Iritis is another potential complication of corneal injuries. When some types of plant matter, such as the needles of pine trees, are the injuring factor, they can cause the iris (the colored center of the eye) to become swollen, a condition called iritis. Iritis has many other causes, but requires immediate medical attention as it can cause much more serious and long-term eye problems, such as glaucoma.
