How to Treat a Scratched Cornea
One of the most common injuries seen in an ophthalmologist’s office is a scratched cornea, also known as a corneal abrasion.
In my 22 years in ophthalmology, my main specialty was the cornea. I have seen thousands of scratched and lacerated corneas, and almost as many causes of those injuries.
But the treatment of these injuries is typically the same. However, many ophthalmologists forget to tell patients the number one way to allow the cornea to heal much more quickly - keep it moist. Let's take a look at why that's the key.
The cornea gives the eye 70 percent of its focusing power and acts like a window. When the window becomes dirty, it’s difficult to see through it.
The cornea becomes “dirty” when it is dry, injured or edematous (swollen). Corneal scratches, among other things, can cause both edema (swelling) and dryness which exacerbates the injury and clouds the window.
In order to better understand corneal abrasions, we need to know a little about the structure of the cornea. Here’s a crash course in corneal anatomy:
The cornea is an amazing cellular matrix. It is protected from the environment by the tear film, eyelid and eyelashes. It is densely packed with nerve endings and has no blood vessels. Despite this, it is the fastest healing part of the body, usually healing itself within 24 hours.
The cornea is comprised of five layers:
- The Epithelium – the first layer of the cornea is very thin and heals very quickly. It does not scar because it is the only part of the body that can actually regenerate.
- Bowman’s Membrane – the function of this second layer of the cornea is unclear. It is acellular (meaning it is not made of actual cells, instead it is made up of primarily collagen fibrils. These fibrils create a layer that allows cells to attach to it, so it is assumed that this membrane exists for the epithelium and stroma to attach to it.
- The Stroma – the third layer of the cornea and the thickest layer. The stroma gives the cornea its shape and stability. It is usually injured by deep lacerations, although this is rare. The stroma does not regenerate and when injured typically leaves a scar, which results in loss of vision if the scarring is in the visual axis (in front of the pupil).
- Descemet’s Membrane – this fourth layer is very elastic because it is made up of type III collagen. If cut, this layer will retract, and it has no regenerative properties. It is the basement layer of epithelial cells to attach to the rest of cornea.
- The Endothelium – the last layer of the cornea maintains corneal deturgescence (relative dehydration that maintains corneal clarity) and is comprised of about 500,000 cells. In layman's terms, this layer of the cornea hydrates the rest of the layers, keeping the window clear.
The epithelium, Bowman’s membrane, and the stroma are the three layers most commonly affected by injuries such as corneal scratches, abrasions, and lacerations. Most abrasions, however, only affect the epithelium, meaning these injuries do not typically leave a scar and heal very quickly.
What Causes a Scratched Cornea?
Just about anything can cause a corneal abrasion. But there are several causes of scratched or abraded corneas that we see more often than others. The most common culprits that can cause these injuries are:
- Fingernails (especially those of a newborn)
- Mascara Wands
- Tree branches and limbs
- Metallic or other foreign bodies
- Chemical burns
Many women are victims of the “mascara wand abrasion” as it’s affectionately known. Women putting on mascara in the morning get a little bit to close to the eye and nick the cornea with the mascara wand. This can be a simple abrasion that heals within hours, or it can be a bit more sinister and have mascara embedded in the abrasion, requiring a physician to debride the wound (clean it).
Abrasions caused by tree branches or limbs, metallic foreign bodies, and chemical burns, are the most damaging to the corneal tissue. Some corneal injuries need to be treated right away to prevent scarring and potential blindness including:
- Abrasions caused by plants or plant debris can cause a secondary fungal infection, which is very difficult to treat.
- Metallic foreign bodies can leave rust rings which need to be removed with a corneal burr (a small drill-like tool) and can leave scar tissue if they are deeply embedded.
- Chemical burns can damage many layers of the cornea (not just the epithelium) resulting in scar tissue that distorts the vision. Many chemical burns are caused by a liquid that is an acid, alkali or a base. Contrary to popular belief, an acid does not do as much damage to the cornea as an alkali. The alkali class of chemicals eat through the cornea quickly and can affect other structures in the eye.
Scratched corneas are not only very painful because of the number of nerve endings, but abrasions can also be very disruptive to one’s life. In fact, if left untreated, many corneal abrasions can cause a secondary infection, or even a corneal ulcer, which can leave permanent scarring. Sometimes this scarring can lead to blindness, which can only be reversed with transplant surgery.
Corneal Foreign Body
People Who Most Commonly Suffer Corneal Abrasions
Some people are more likely to suffer from a scratched cornea or foreign body than others. Many occupations are more prone to ocular injuries of this type, as are some hobbies such as gardening. Some of the people most commonly affected by this type of injury are:
- Moms of newborns - infants may hit mom in the eye with their hand, scratching the cornea with their thin, sharp fingernails.
- Auto mechanics – working on engines puts mechanics in contact with metal flakes that can become embedded in the cornea and form rust rings.
- Gardeners/groundskeepers – it is quite common for sticks to poke a gardener in the eye, or dirt and debris to fly into the eye and embed itself in the cornea.
- Clerical and office workers – those who work with paper all day are prone to paper cuts, including paper abrasions on the cornea. I’ve seen patients with paper lacerations down to the stroma.
- Janitors – cleaning chemicals can accidentally get into the eyes when they are sprayed, or if the person rubs their eye without washing their hands.
- Welders – flash burns are quite common among welders and are considered abrasions because of the damage they do to the epithelium.
- Contact Lens Wearers - patients who wear contact lenses are more likely to get things such as lint or other debris under their lens, which can then either abrade the cornea or become embedded in it. Contact lens wearers are also more prone to corneal ulcers which can cause permanent damage and even blindness.
Symptoms of an Abrasion
The most well-known symptom of a corneal injury is pain, but there are other symptoms as well. The most common symptoms of an injury to the cornea include:
- A foreign body sensation, or a feeling of something in the eye
- A dry, scratching sensation
- Sensitivity to light
- Conjunctival injection, or a red eye
- Pain when blinking
- Sharp, shooting pain often described as a needle poking the eye
- Swollen and red eyelids
If you have any or all of these symptoms, see your ophthalmologist right away.
A Corneal Ulcer
What to Expect When You See Your Doctor
When you visit your doctor, you’ll initially be seen by the technician who will check your vision and ask you several questions. Be prepared to answer the following:
- What are your symptoms? Do you have the sensation that something is in your eye?
- Are you sensitive to light? Is your eye tearing and burning? Is your vision affected?
- When did the initial symptoms occur?
- How severe are the symptoms on a scale of 1 to 10, 10 being the worst?
- What were you doing prior to the beginning of the symptoms?
- Did you get something in the eye? Were you hit in the eye with anything?
- Did you flush the eye if you suspected a chemical or a foreign body got into the eye?
After the initial interview with the technician, the doctor will instill an anesthetic to make you more comfortable and then examine your eye by staining it with a yellow dye known as fluorescein and looking at it under a slit lamp (a microscope).
This stain highlights any defects in the epithelium so that the doctor can easily see the abrasion, scratch, laceration or foreign body.
If the doctor suspects a foreign body, but cannot find one, he or she may flip the upper eyelid to see if it is embedded on the underside of the lid. This can be uncomfortable, but is necessary to prevent further injury.
Treating a Scratched Cornea
Scratches and abrasion heal very quickly, usually within 24 to 48 hours, as long as they are superficial and affect only the epithelium.
Most ophthalmologists will put a patient on an antibiotic eye drop to prevent a secondary infection, and tell the patient to keep the eye closed.
Some doctors will put a pressure patch on the eye to prevent blinking; however, a contact lens used as a bandage is more common.
Bandage Contact Lenses
A contact lens can be placed in the eye and used as a “bandage.” This prevents the lid from sloughing away regenerated epithelium with every blink. It also prevents the excruciating pain associated with abrasions while still allowing the eye to be used.
The contact lens will also absorb the drops put in the eye allowing the antibiotic to stay in the eye longer. This is currently the preferred method of treatment for corneal abrasions.
A pressure patch is exactly what it sounds like. A patch is put on the eye in a way that keeps pressure on the eyelid so that it is unable to move. This keeps the lid from sloughing away regenerated tissue as well as keeping the patient comfortable.
Unfortunately, there is the disadvantage of the inability to put drops in the eye because the patch is left in place until removed by the doctor. However, an antibiotic ointment can be instilled prior to patching to help prevent infection.
Pressure patches are not used as frequently today as they have been in the past. Depending on the severity of the abrasion and the patient’s comfort level, a doctor may occasionally choose to use this method.
In an effort to control pain, patients are advised to use over-the-counter analgesics to alleviate symptoms. Medications such as Ibuprofen, Aleve and Tylenol can provide some relief.
Narcotic pain relievers are not recommended.
These medications cause the eyes to become dry which can slow the healing process and even lead to corneal ulcers. If you must take a narcotic pain medication such as hydrocodone (Vicodin) or tramadol (Ultram), it is recommended that you use preservative artificial tears at least every 30 minutes to keep the eyes moist and promote healing. You may also want to use an ointment before bed such as Refresh PM.
If you do not have a pressure patch, or a bandage contact lens, the only thing that will make the eye feel better is bathing it in artificial tears and keeping the eye closed. Using the artificial tears every 30 to 60 minutes will keep the cornea moist and facilitate healing by protecting regenerated tissue from the lid, as well as nourishing the cornea with moisture.
Corneal Foreign Bodies
If you have a corneal foreign body, it will need to be removed. The doctor will anesthetize your eye, and remove the foreign material. If the debris was metallic in nature, the doctor will use a device known as a corneal burr, or Alger brush, to remove any rust ring that may be left behind.
The corneal burr is essentially a drill similar to a Dremel tool that makes removal of residual rust rings much easier. Needles and Q-tips can also be used.
Dr. James Kirkconnell Discusses Treatments for Scratched Corneas
What to do if You Think You Have a Corneal Abrasion
If you think you have a scratched cornea or a foreign body in your eye, you need to see your ophthalmologist right away.
DON'T RUB YOUR EYE!!
It's natural to want to try to get something out of your eye, but rubbing it can make things worse. If you have something under your eyelid, rubbing the eye cause the foreign body to scratch the cornea or become embedded in the cornea.
If you already have something embedded in your cornea, rubbing the eye can push the foreign body further into the cornea, making it much more difficult to remove and increasing the risk of scarring.
Blinking several times may be enough to move the debris out of the eye, but if not, the next option is to flush it, preferably with artificial tears or sterile saline solution, but tap water will suffice in a pinch.
If you have gotten a chemical in your eye, you need to flush the eye continuously for at least 15 minutes. If you can, have a friend or loved one call your ophthalmologist while you continue to flush your eye. If no one is around to help you, flush your eye for 15 minutes, and then call your eye doctor.
If left untreated, abrasions can become infected or evolve into corneal ulcers or corneal erosions. Even if you don't think there is something actually in your eye there might be, and you should call your ophthalmologist right away.
It is best to avoid going to the emergency room if at all possible. An ER typically does not have the equipment needed to deal with this kind of injury. It is best to see your ophthalmologist as soon as possible.
If you can't get to your eye doctor right away, keep the eye moist with artificial tears (preferably preservative free) or keep the eye closed to prevent further irritation until you can get to your eye doctor.
For a more in-depth look at the cornea see Definition of the Cornea
Questions & Answers
© 2012 Melissa Flagg OSC