A corneal abrasion is a scratch on the eye's cornea. The cornea is the clear, protective lens that (like a car windshield) is in front of the iris, which is the colored part of the eye, and the pupil -- the black circle in the middle of the eye.

It's important both for vision and for protecting the eye. If you poke your eye or if something gets trapped under your eyelid -- such as dirt or sand -- your cornea may become scratched. When it does, it can cause significant pain and discomfort.

If you get something in your eye, do not rub it. Try flushing it out with water or seek help from a doctor.

WebMD takes a look at the causes of corneal abrasion, its symptoms, and what to do if you scratch your eye.
Causes of Corneal Abrasion?

Many situations can cause a corneal abrasion, including:

• Being poked in the eye, for instance by a fingernail, plant, pen, ormakeup brush
• Dirt, sand, sawdust, ash, or some other foreign matter blowing into your eye and getting caught under the eyelid
• Chemical burns
• Aggressively rubbing your eye
• Poor fitting or dirty contact lenses
• Certain types of eye infections
• Not protecting the eyes during surgery while under general anesthesia (If your eyes are not taped closed during surgery, the cornea can dry out, making it more prone to corneal abrasion.)

Symptoms of a corneal abrasion do not always happen immediately. As a result, it's often hard to know what caused it.

When Something Gets in Your Eye

Often, the first reaction to something getting in your eye is to want to rub it. But don't -- rubbing can cause an abrasion. Here are some safer ways to try to remove foreign matter from your eye:

• Blink your eye several times.
• Pull your upper eyelid over the lower eyelid.
• Gently rinse your eye out with clean water or a sterile saline solution. But do not rub the eye while rinsing it.

And do not try to remove anything that is on the cornea. Only a doctor should do this.

If you still feel like something is caught in your eye, see an eye doctor as soon as possible, or go to the emergency room. The eye doctor will examine the eye and use a special eye stain to better see the surface of the cornea. If something is on the cornea, the doctor can safely remove it.
Symptoms of Corneal Abrasion
Once you've had a corneal abrasion, you're not likely to forget the unrelenting pain and discomfort it can cause. Symptoms of corneal abrasion may include:

• Feeling like you have sand or grit in your eye
• Eye pain, especially when opening or closing your eye
• Tearing and redness
• Sensitivity to light
• Blurred vision or loss of vision

Corneal Abrasion Treatment

Antibiotic eye drops or ointment may be recommended to prevent an infection in cases of corneal abrasion. Medicated eye drops to ease pain and inflammation may also be used.

Sometimes, doctors temporarily patch the scratched eye. Painmedication may also be given.

A minor scratch should heal on its own in one to three days. More severe abrasions may take longer to heal.

Here are some tips to help you while your eye heals:

• Do not wear contacts until your eye has completely healed and your eye doctor says it is safe to do so.
• Wear sunglasses to help ease pain caused by the glare of the sun.
• Do not rub your eye.

Most people fully recover from minor corneal abrasions without permanent eye damage. However, deeper scratches can cause corneal infections, cornea erosion, or scarring of the cornea. If not treated properly, these complications can result in long-term vision problems. Any unusual symptoms, including a recurrence of pain following healing, should be reported to your eye doctor.