Wednesday, December 16, 2009
Corneal Abrasion, Corneal Scratch, Pain and Sensation of Something in the Eye
There are a number of reasons why a cornea might be scratched or irritated resulting in an abrasion. Although they are extremely tiny, corneal abrasions, are very painful . . . and why not? After all, even a paper cut to our fingertips can cause startling pain. Often a small corneal abrasion will heal itself within 24 hours. There is treatment that may soothe the affected eye, such as sterile artificial tears (see below for further discussion of additional treatments). Keep in mind, however, not all eye pain is due to a corneal abrasion, and not all corneal abrasions may be treated with home care alone.
Some Structures of the Eye
To understand what the cornea is, it’s useful to think of the eye as a room with the cornea being a window. The eyelids are similar to shutters that can be opened or closed. The space between the shutters and the window glass is the conjunctiva. The cornea functions as the window glass does; that is, the light flows through the cornea to enter the eye. Directly behind the cornea is the round, colored iris which functions in much the same way as curtains; the muscles of the iris expand and contract to allow more or less light inside of the “room.” The pupil is the space through which the light passes between the open curtains. The lens is yet another “window pane” that the light passes through before it enters the room. My suggestion is to think of the lens, for this example, as a large glass “sun catcher” suspended from the ceiling just inside the window. Vitreous humor is the gelatinous substance that fills the center of the eye just as normal atmospheric gasses fill up a room in your home. The retina is the back wall of the room just opposite from the window. As light strikes the “wall” (retina) there is inevitably a particular spot where the sunlight is more concentrated. The macula in the back of the eyeball is similar to that part of the room with the brightest exposure to the light. The fovea is an area of the macula which provides the sharpest vision; similarly the brightest spot in the room is best for reading or performing tasks that require sharp visual acuity.
(See a nice depiction of the eyes' anatomy here: http://www.eyecareamerica.org/eyecare/anatomy /).
A Little More About the Cornea
As mentioned in the preceding paragraph, the cornea functions like the glass of our windows. It’s a protective structure for the more delicate features behind it, and it functions to let light flow into the eyeball. Although the cornea consists of five distinct layers, it is very thin—with a depth of only about 1 mm at its deepest point.
The cornea has an abundance of nerve endings, as a result it’s very sensitive to both touch . . . and pain.. That trait helps protect our vision from trauma as all of our instincts quickly react to try to prevent an injury to the eye. However, corneal abrasion is still one of the most common eye injuries.
How Does a Corneal Abrasion Occur
A person may have no recollection of trauma to the eye and there are numerous scenarios that may result in a corneal abrasion. A poke in the eye (particularly if a fingernail is involved), a branch from a tree, flying glass or metal shards, or a surgical drape or equipment brushing across your eye if it is exposed during a surgical procedure . . . any of these things can cause a corneal abrasion. Debris in the eye can also cause an abrasion, particularly when the eyes are rubbed vigorously or if a contact lens causes friction.
Prevention during Surgery
Taping the eyes closed is a standard preventive measure aimed at protecting the eyes from corneal abrasion. Some surgeries pose a greater risk of a corneal abrasion occurring. Those in which the patient is positioned face down, surgery on the head or neck, and any lengthy procedure carries more risk. Of course in some surgeries taping is contraindicated as the eyes may need to be opened during the procedure. In such cases the anesthesiologist or nurse anesthetist will use their judgment to make the appropriate decisions. Instillation of eye drops, gels or eye ointments may be the decided course of prevention, or special goggles, eye cushions or pads may be used.
Your doctor may use a combination of fluorescent dye and either a cobalt-blue filtered ophthalmoscope or a “slit-lamp” to make a definite diagnosis of a corneal abrasion. The physician may instill drops to temporarily numb the eye during the exam. If they observe a foreign body present in the eye, it will also be removed during this examination.
At one time eye patches were applied when patients suffered a corneal abrasion. This is no longer a standard treatment; however, in some cases your physician may determine that an eye patch is in your best interest. It’s more likely that eye drops or ointment will be prescribed for home use. The drops and/or ointments may include a medication to control the pain, an eye lubricant, a topical antibiotic, or a steroid. Steroid eye drops may be prescribed to reduce inflammation. (Please note, some of the eye drops and ointments may result in temporarily blurred vision). Occasionally, a pain medication to be taken by mouth will be prescribed as well.
If metal shards were responsible for your eye injury, a tetanus booster shot will be needed. If it has been more than 5 years since your last tetanus shot--or if you cannot remember when your last tetanus shot was given--you will should be given a booster shot after the eye examination.
Follow your physician’s orders and use the medications exactly as prescribed. Do not stop the medication sooner than the directions tell you to simply because the eye “feels better.” Continuing the full course of prescribed treatment is important to prevent possible complications later on.
If you have questions about your doctor’s ordered treatment, ask him or her. You have a right to know the reason for the treatment decisions that are made on your behalf.
How long to heal
A small corneal abrasion may heal in a few hours. Often after a night’s sleep the cornea has healed. In the case of a larger abrasion, it may take several days time for complete recovery. It is important to keep from rubbing the affected eye as that may delay healing. If the symptoms suddenly recur after the initial healing phase, consult your physician right away. Inadequate treatment of a corneal abrasion can sometimes lead to complications such as a corneal erosion.
First Aid for Eye Emergencies
Plan to seek treatment at your urgent care center or ER for any bleeding from the eye, chemical splash, visible scratch or penetrating injury, eye pain, double or blurred vision, nausea and headache.
Do not rub the injured or irritated eye. Wash your hands with soapy water. Remove contact lenses if they are in place. Do not attempt to use any tweezers or cotton swabs to try to treat eye emergencies at home.
Chemical splash to the eye: Start flushing the eye with cool clean water from a sink, bottle, hose, etc. Tilt the head back and to the side. Keep the affected eye wide open and pour the clean water gently but directly into the eye. Make sure the head is tilted away from the “good eye” so that chemicals which are rinsed out don’t flow into that eye during the flushing process. (A child might be more comfortable laying down in an empty bath tub to have the eyes irrigated.) Continue to flush chemicals from the eye continuously for at least 15 minutes. Call 911 or have someone drive you to the ER. If the chemical that splashed into the eyes is known, be sure to provide the name to the healthcare providers at the hospital. For more information see:
First aid tips for a chemical splash to the eye from the Mayo Clinis.
Foreign body in the eye: Do not rub the eye. With clean hands, open the eye and allow tears to move the foreign body (such as an eyelash or speck of dirt). Rinse the eyes with cool clear water as explained above if tearing isn’t effective. If an object is embedded in the eye—do not attempt to remove it. Seek medical help in the ER or urgent care center immediately. For more information see: Mayo clinics advice on corneal abrasion and Mayo's first aid advice for a foreign body in the eye.
Bleeding from an eye: Do not put any pressure on the eye, gently cover it with a clean cloth and go directly to the Emergency Room. (The person with the injured eye should not drive).
2009 All rights reserved for content and photos, Carolyn Cooper, MPH, RN
WebMD: http://www.webmd.com/eye-health/tc/objects-in-the-eye-home-treatment and http://firstaid.webmd.com/corneal-abrasion-treatment
Eye Safety for Emergency Response and Disaster Recovery from the CDC: www.cdc.gov/niosh/topics/eye/eyesafe.html
Wilson, S.A. and Last, A. (2004). Management of Corneal Abrasions. American Family Physician. Retrieved 12/16/2009 from: http://www.aafp.org/afp/2004/0701/p123.html
Verma, A. (2009). Corneal Abrasion. Emedicine from WebMD. Retrieved 12/15/2009 from: http://emedicine.medscape.com/article/1195402-overview
First Aid for Eye Emergencies from Prevent Blindness: http://preventblindness.org/safety/firstaid.html
Tarmey, N. & White, L.A. (2009). Chapter 5, Damage to the Eye. Risks associated with your anaesthetic, Information for patients: the Royal College of Anaesthetists. Retrieved 12/16/2009 from: