A scratched eye is the usual term we use for what eye specialists call a superficial corneal abrasion or corneal laceration. Patients with this eye injury typically make up around 10% of all new visits to the ophthalmic emergency care, and although it’s minor, the injury can cause significant discomfort.
Mr Radwan Almousa, one of our top consultant ophthalmologist based in London, explains what a corneal abrasion is exactly, what the usual causes are and walks us through the typical treatment plan that an ophthalmologist would offer.
What is a corneal abrasion?
Abrasion in the eye typically affects the superficial layer of the cornea - mainly the epithelium and possibly the epithelial basement membrane. To better understand these affected parts, we need to first understand certain parts of the eye and the layers that make up the cornea.
- Cornea - the cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber.
- Epithelium - the corneal epithelium is the outermost layer of the cornea and acts as a barrier against fluid loss and pathogen penetration.
- Epithelial basement membrane - this is a sheet of proteins and other substances beneath the epithelium and forms a barrier between tissues.
- Tear film - the tear film is a unique thin fluid layer that covers the outer surfaces of the eye.
On average, the cornea thickness is about 0.5mm and the epithelium is approximately 0.05mm. This makes up around 10% of the overall thickness of the cornea and is made of 6 layers of epithelium cells.
The epithelium, together with the tear film, contributes to the maintenance of the optically smooth corneal surface.
Most of the time after scratching your eye, you will only damage the epithelial cells and possibly disrupt the intercellular connections. However, if the scratch is deeper and you break the hemidesmosomes (the connection between the epithelial cells and the underlying basement membrane), it may cause recurrent corneal erosion syndrome (RES) which is a condition resulting in relapsing and painful episodes of corneal abrasions.
What causes corneal abrasions?
A corneal abrasion is usually caused by a fingernail scratch, which can be your own doing or your baby or child. Other times, it can be the result of blunt trauma, such as walking into something or a foreign body entering the eye, like grit or sand.
What are the symptoms of a corneal abrasion?
The cornea is a very sensitive part of your body. A small scratch can be quite painful, as it exposes the sensory nerve endings, making the scratch feel much bigger than it actually is. The usual symptoms of a corneal scratch are:
- Sharp pain
- Watery eyes
- A gritty sensation in your eye
- Photophobia (light sensitivity)
- Sometimes blurred vision
An ophthalmologist can detect a corneal scratch using a slit lamp examination, which will allow them to see the exposed epithelium.
RES causes sharp painful eyes, usually after waking up, and the condition is also associated with similar symptoms such as watery, red eyes and photophobia. Often, the patient presents with a history of a scratched eye, which could date back to a few days or a few years ago. Most of the patients I see have developed RES from a baby fingernail scratch.
How can I prevent a corneal abrasion?
When we have something in our eyes, we have a tendency to rub them, thinking it will make the object go away. Sometimes, this actually causes more damage. Try to wash your eyes out gently with water instead of rubbing them.
There are some groups of people that are more prone to corneal abrasions. For example, if you work in an environment with flying dust particles - like builders or field workers - it is advisable to wear protective goggles at all times to prevent foreign bodies from embedding the cornea.
As for parents with babies, they need to keep aware that infants would like to explore, sometimes using their hands to inspect parents faces, which might, unfortunately, cause a corneal scratch. So keeping babies fingernails clipped with no sharp edges could be a good preventative measure.
How do you treat a scratched eye? Does it clear up by itself?
In general, corneal abrasions will heal without treatment within 1-2 days, depending on the size of the damaged epithelium layer.
- Lubrication & bandage contact lenses - eye drops can provide lubrication and help speed up the healing process. Bandage contact lenses may also provide comfort and prevent rubbing from the blinking eyelids. If the corneal scratch is deep enough to rupture the basement membrane and the patient develops RES, then lubricating eye drops and gel are the first line of treatment to prevent painful episodes upon waking up.
- Antibiotics - Some people decide to cover the eye with antibiotic drops until the defect heals. This is a good strategy to prevent infection as the epithelial layer has ruptured and is the eye’s first layer of defence against pathogen penetration.
- Hypertonic ointment - If previous treatments are not enough, then applying hypertonic ointment, such as sodium chloride ointment 5%, during sleep would help prevent swelling. This swelling typically happens during the closure of eyelids and supposedly triggers the breaks in the epithelium layer in RES.
The course of sodium chloride eye ointment is usually for six months, as the usual time for the hemidesmosomes to establish an adequate connection between the epithelial layer and basement membrane, is around four months.
Is surgery ever needed?
If all treatments above fail to provide relief, the next step in the treatment ladder would involve surgery, such as epithelial layer debridement or applying laser treatment on the surface of the cornea. Both methods are to encourage strong adhesion between the epithelial layer and the underlying tissue.
Mr Radwan Almousa is a highly-skilled consultant ophthalmologist based in London. If you believe you have any of the symptoms mentioned in this article, you can talk to him by booking an e-Consultation through his Top Doctors profile.