Minor scratches or abrasions to the cornea are common. They usually heal in 24-48 hours. A course of antibiotic eye drops or ointment is commonly prescribed to prevent an eye infection from developing. More serious injuries to the eye may occur from small flying particles hitting the eye at high speed. This can occur when drilling, sawing, chiselling, grinding, lawn mowing, etc, without eye protection. Serious injury can also result from chemical burns. Always see a doctor for a proper eye examination if you suspect that your eye has been injured from a small flying particle, or from a chemical. Note: all chemical eye injuries are potentially blinding injuries. Treat with immediate first aid: remove contact lenses if present and immediately wash out the eye with lots and lots of water for at least 10-15 minutes.
What causes corneal injury?
The cornea is at the front of the eye. It is a clear disc which lies over the front of the coloured part of the eye and the pupil. It's the window you see out of, and it is protected from harm by:
- Lubrication (in the form of tears).
- Rapid blinking of your eyelid if anything approaches it.
The blink reflex normally protects the cornea well from most injuries. However, scratches and minor injuries to the cornea are quite common. For example, a scratch from a hairbrush, by a fingernail when putting in a contact lens, from walking into a tree branch, etc.
The pain can be quite bad, even from a small scratch, as the cornea is extremely sensitive. The eye will water profusely and you may be unable to bear to open it at first.
Small flying objects
If you use a drill or other types of power tools like grinders without wearing eye protection, you may injure your cornea. This can happen from small flying particles of metal, wood, or other materials. These can fly out extremely fast and be so small that the eye does not see them coming and therefore does not blink. They may also be hard and sharp. Several things can then happen:
Sometimes the particle gets stuck in the cornea. This can can cause pain similar to a corneal scratch.
Sometimes the particle goes straight through the cornea to a deeper part of the eye. If the particle is small this can be painless at first, or cause only minor pain. It may also pass through the sclera or white part of the eye into the deeper parts too. If this happens there may be no noticeable pain. This penetration of the eye itself can be very serious. It may lead to infection inside the eye, and loss of fluid from inside the eye and can permanently affect your vision. You should always see a doctor for an eye examination if you suspect a particle has flown into your eye when you have been drilling, sawing, grinding, chiselling, lawn mowing, etc.
Sometimes, a chemical may splash on to the front of the eye and cause a burn to the cornea. Household cleaning products like oven cleaner and bleach can do this. The eye can also be irritated by alkaline substances like plaster dust.
The most common form of radiation damage is called arc eye. It's also sometimes called snow blindness. It occurs when the eye has been exposed to very bright light without proper eye protection. This is common if welding without eye protection. Symptoms typically include severe eye pain with watering eyes that may not develop until several hours after the exposure. Eyes can be too sore to keep open.
Other causes of radiation damage to the cornea include:
- Exposure to a lot of reflected sunlight (for example, snow blindness).
- After ultraviolet light exposure by looking at the lights in tanning machines.
Although the pain can be severe, the condition usually resolves without complications within 1-2 days.
Examination of the eye
If you suspect you have a corneal injury, it is best to see a doctor. In particular, if you suspect an injury from a flying small particle or from a chemical you should see someone quickly. This may mean attending accident and emergency. A doctor may use a magnifying instrument to examine your eye. A drop or two of a special dye (fluorescein) is commonly put on the front of the eye if a corneal injury is suspected. This shows up scratches that might otherwise not be seen. The eye examination also checks for serious damage.
What is the treatment for a corneal injury?
Treatment for a chemical burn to the eye
All chemical eye injuries are potentially blinding injuries. Treat with immediate first aid:
- Remove contact lenses if present.
- Immediately wash out the eye with lots and lots of water for at least 10-15 minutes. For example, hold your (open) eye beneath a running cold tap (testing the temperature first).
- Alkalis are particularly damaging, and any loose bits such as lime should be completely washed out. Check no bits are left behind the eyelids.
Then go to your nearest accident and emergency department as soon as possible. You should be assessed urgently by an eye specialist.
Treatment for scratches/abrasions/flying objects/radiation injury
A small corneal scratch usually heals over a couple of days or so.
Eye infection is a complication that may follow an injury or scratch to the cornea. Therefore, it is routine to prescribe antibiotic eye drops or ointment for up to a week to prevent infection. Painkillers such as paracetamol or ibuprofen will ease pain. Sometimes a one-off eye drop may be given by a doctor to help ease the pain.
Sometimes a small particle of wood, metal, etc, becomes slightly embedded in the cornea. This needs to be removed, as it may lead to infection or staining. It is often possible for a doctor to remove it using a cotton wool bud. Sometimes a fine needle may be needed to lift it out. Local anaesthetic eye drops are used if this is done, to make the procedure painless. The surface of the eye is actually surprisingly hard so don't worry. The doctor will not harm your eye with the needle.
If you normally wear contact lenses, do not wear them while the cornea is healing or whilst using antibiotic eye drops. Do not wear them for 24 hours after the final dose of antibiotic eye drops.
An eye patch to cover the eye is not normally advised following a corneal scratch or abrasion (as was commonly advised in the past). This is because studies have shown that using a patch does not improve healing rates and does not reduce pain. Removal of the patch tends to result in the healing tissue on the cornea stripping off again as you blink so you are back to the start of healing again. In addition, if you wear an eye patch you lose your binocular vision (vision using two eyes). The exception is if local anaesthetic eye drops have been used for assessment or treatment and the eye is numb. A patch may then be advised for a few hours until the sensation returns to the eye in order to protect it. An eye with anaesthetic drops in it may not blink if something flies into it.
You will be referred to an eye specialist if you have a deep or penetrating injury to the eye or if there are any concerns that the eye is more seriously damaged. Specialised assessment and treatment may be needed.
Note: do not drive unless you have normal vision and the effects of eye drops (if used) have worn off.
Prevention of corneal injuries
Always wear eye protection when you drill, saw, etc, which causes flying small particles. Also when welding, skiing, mountaineering, using sunbeds, and in any other situation where there is a lot of light radiation.
Depending on the circumstances and severity of the injury, your doctor may advise that you should be reviewed in 24-48 hours after the injury. This is to see if healing is underway. However, see a doctor as soon as you can if your vision gets worse or if you have worsening pain. (Allow for the fact that, if any local anaesthetic was used, there will be mild pain after it wears off.)
Dr Tim Kenny
Dr Mary Lowth
Dr Helen Huins