Definition The cornea (corn-ee-ah) is the clear window on the front of the eye that covers the coloured iris and pupil. Injury to the cornea causes hazy vision and scarring. It can also cause a loss of vision.
What are the signs and symptoms of the injury? The symptoms of a corneal injury may include:
a feeling that there is something in the eye
sensitivity to light
bleeding from the surface blood vessels of the eye
swelling of the eye
What are the causes and risks of the injury? The most common corneal injury is a scratch. This causes extreme pain because the cornea has many small nerve endings in its surface. Foreign objects, such as metals, can cause damage to the cornea. Chemicals or toxic substances splashed into the eye can also cause corneal injury. Mild soap can burn and irritate the top layer of cells on the cornea. Products such as bleach, ammonia, lime and liquid fertilisers with ammonia can permanently scar the cornea. The cornea can be injured by a ball or fist hitting the eye. Injury can also be caused by a cut with a sharp object such as a dart, pencil, or knife. Corneal injury should be suspected if the cornea is cloudy and if there is an irregular pupil, even if there is no pain.
What can be done to prevent the injury? In any job, hobby, or sport where there is a danger of injury to the eye, a person should wear safety glasses or goggles.
How is the injury recognised? Many injuries cannot be seen with the naked eye. Diagnosis of a corneal injury is best made with a microscope. This is done by an eye care professional using an instrument called a slit lamp. A slit lamp is a microscope and a rectangular light source used to examine the cornea. Often, the cornea is stained with fluorescein.
What are the treatments for the injury? Treatment involves carefully removal of the object by a doctor, usually after treating the eye with topical anaesthesia to numb the area. Sometimes removal of the object can be done with a cotton-tipped applicator moistened with saline or salt water. If this does not work, the object must be removed, under the microscope, with a small instrument. Once the object has been removed, the eye must be treated with an antibiotic, such as chlroromycetin or tobramycin, either in drop or ointment form, to prevent further damage. An eye doctor should follow a person who suffers large corneal scratches.
Anaesthetic drops should not be used in eyes with corneal scratches because the drops can damage the cornea and slow healing. Eye drops or ointments that contain corticosteroids (cort-i-co-stare-oids), such as prednisolone or prednisolone, should not be used.
If chemicals get into the eye, the person's eye should be washed with water. The eyelids must be held apart so that all parts of the eye are washed. This washing must be done within minutes of the injury. If mucous or matter is found under the lids, even minutes or hours after the initial injury, it must be removed. If there is suspicion of injury, a doctor should be consulted. A doctor should always examine chemical burns to the eye. The burns can be severe and damage the eye in a short period of time. These types of injuries can result in complications, even years after the initial injury. In cases of scratches and chemical burns, a doctor will use dilating drops and antibiotics.
For cuts to the cornea or penetrating injuries to the eye, repairs must be done immediately. These repairs are most commonly done with general anaesthesia. General anaesthesia means the person is put to sleep with medications.
What are the side effects of the treatments? There are complications with any surgery or anaesthesia. These include bleeding, infection and reaction to the anaesthetic agents. The person may have an allergic reaction to the eye drops or ointment.
What happens after treatment for the injury? Sometimes the injured area will not heal, causing recurrent corneal erosions. In this situation, the top layer of cells is only loosely attached to its base. These cells may come off several weeks or months later. When this happens, the person may feel like something is in his or her eye. The person also will be sensitive to light. Use of antibiotic drops and rewetting drops to keep the cornea wet will usually help the eye heal. Frequent rewetting of the cornea is necessary, over months, to allow this area to heal completely. This sometimes requires help from an eye doctor or opthalmologist.
Author: Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
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