The cornea is the clear, protective outer layer of the eye that plays a crucial role in focusing vision. Because it is exposed to the environment, the cornea can be injured through minor scratches or abrasions.
What Is a Corneal Scratch?
A corneal scratch, also known as a corneal abrasion, is a disruption or loss of the outermost layer of the cornea called the epithelium. This can occur due to trauma from fingernails, contact lenses, dust, tree branches, or other foreign objects. Even minor injuries can cause significant discomfort due to the high density of nerve endings in the cornea.
Symptoms of a corneal scratch usually include sharp eye pain, redness, tearing, sensitivity to light, blurred vision, and the sensation of something being in the eye.
How Does a Corneal Scratch Lead to Infection?
The corneal epithelium acts as a barrier to bacteria, viruses, and fungi. When this layer is disrupted by a scratch, it creates an entry point for microorganisms to invade deeper corneal tissues. This increases the risk of developing a corneal infection or keratitis.
Infections after corneal abrasions can involve various organisms. Bacterial keratitis is the most common and can result from contamination of the injured cornea. Contact lens wearers are especially at risk for infections with Pseudomonas aeruginosa, a particularly aggressive bacteria. Viral infections such as herpes simplex virus may also affect the cornea following trauma.
Without timely treatment, corneal infections can progress rapidly, damaging the cornea and potentially causing vision loss.
Risk Factors for Eye Infection From a Scratch on the Cornea
Not all corneal scratches lead to infection. The risk depends on factors such as the size and depth of the abrasion, presence of foreign material, hygiene, contact lens use, and the patient’s immune status.
Wearing contact lenses with a corneal abrasion significantly increases infection risk. Poor lens hygiene, sleeping in contact lenses, or prolonged lens wear worsen this risk.
Delays in seeking medical care and failure to properly clean the eye after injury can also contribute to infection development.
Symptoms of Corneal Infection
Symptoms of infection may overlap with those of corneal scratches but typically worsen over time without improvement. Increased pain, severe redness, discharge, decreased vision, sensitivity to light, and a white or gray spot on the cornea are warning signs.
If you experience these symptoms after a corneal injury, immediate evaluation by an eye care professional is necessary.
Diagnosis of Corneal Infection
Eye care providers diagnose corneal infections using a detailed eye examination with a slit lamp microscope. They look for signs such as corneal infiltrates, ulcers, and epithelial defects. In some cases, cultures or scraping of the corneal surface may be taken to identify the causative organism and guide treatment.
Early diagnosis improves the chances of successful treatment and reduces complications.
Treatment of Corneal Scratches and Infections
Treatment of a simple corneal scratch often involves lubricating eye drops or ointments to promote healing and reduce discomfort. Sometimes, antibiotic eye drops are prescribed prophylactically to prevent infection.
For confirmed corneal infections, treatment depends on the type of organism. Bacterial infections require intensive antibiotic eye drops, sometimes given hourly. Viral infections such as herpes simplex are treated with antiviral medications.
It is important to follow the prescribed treatment regimen strictly and avoid rubbing or irritating the eye further.
Prevention and Care After a Corneal Scratch
To reduce infection risk, it is critical to keep the eye clean and avoid touching it with unwashed hands. Contact lens wearers should remove their lenses immediately and consult their eye doctor.
Wearing protective eyewear in environments where eye injuries are likely can prevent corneal scratches. If an eye injury occurs, timely evaluation by an eye care provider ensures proper care to minimize infection and complications.
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