What causes corneal injury?

Corneal scratches/abrasions

The cornea is at the front of the eye. The blink reflex normally protects the cornea 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 may be quite bad, even from a small scratch, as the cornea is very sensitive.

Small flying objects

If you drill or use other types of power tools without wearing eye protection, you may injure your cornea from small flying particles of metal, wood, or other materials.

• 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.
  • However, untreated it can cause permanent damage to the eye.
  • Therefore: 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.

Chemical injuries

Sometimes, a chemical may splash on to the front of the eye and cause a burn to the cornea.

Radiation damage

The most common form of radiation damage is called arc eye. This occurs when someone has been welding without proper eye protection. Symptoms typically inclulde severe eye pain with watering eyes that may not develop until several hours after the welding.

Other causes of radiation damage to the cornea include exposure to a lot of reflected sunlight (for example, snow blindness) or after ultraviolet light exposure 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 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. 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, use a running cold tap to irrigate the eye.
• 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. However, an 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. It is often possible for a doctor to remove this 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.

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. 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 be advised for a few hours until the sensation returns to the eye.

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. Specialist 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.

Follow-up

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, after an eye injury see a doctor promptly if your vision gets worse or if you have worsening pain (allowing for the fact that, if any local anaesthetic was used, there will be some pain after the anaesthetic wears off, but it should not be severe).