Differences between Conjunctivitis (Pink Eye) and Keratitis
Commonly referred to as pink eye, conjunctivitis describes inflammation of the thin transparent layer of tissue that covers the whites of the eye and the inner surface of the eyelid. The result of that inflammation is that the normally white part of the eye looks pink – or red. Similarly, keratitis – the inflammation of the cornea, the transparent part of the eye in front of the pupil and iris – gives the eye a comparably reddened, irritated look.
“They both look like red eye or pink eye. So people come in with either of those saying they have a pink eye,” says Dr. Sonal Tuli, chair of the department of ophthalmology at the University of Florida. “Both can be very uncomfortable.”
Pink eye is significantly more common – affecting an estimated 3 million to 6 million people annually. In comparison, there are more than 70,000 cases of keratitis a year. While probably the best estimate, the figure is based on a study in northern California that looked only at microbial keratitis, which includes keratitis caused by fungus and bacteria. And the incidence of keratitis in the southern U.S. is probably higher, “so that is likely an underestimate of the total cases of keratitis,” Tuli says.
Although less common, keratitis is more likely to have an impact on vision because it affects the cornea. Symptom of keratitis include blurred vision and light sensitivity, though some people with pink eye experience those symptoms as well. Although both are uncomfortable, keratitis tends to be more painful.
- Red eyes.
- A gritty feeling that something is in your eyes.
- Burning or itchy eyes.
- Discharge that’s green, white or yellow, which may cause the eye to “crust” overnight. In some cases, particularly with bacterial conjunctivitis, this can make it hard to open the eye in the morning.
- Excessive tearing.
- Sensitivity to light (photophobia), in some cases.
- Blurred vision is possible as well.
- Eye redness.
- Eye pain.
- Excessive tearing.
- Swelling of the cornea.
- Difficulty opening or keeping eye opens.
- Blurred vision.
- Feeling that something like sand is in your eye.
“With the conjunctivitis, if you are somewhat savvy, you can see that the majority of the redness is inside of the eyelid,” Tuli points out. “So when you pull the lid down it’s very, very beefy red down there.”
By contrast, with mild keratitis, the inflamed area is concentrated around the cornea and less in the periphery. If keratitis is severe, however, the average person wouldn’t be able to tell the difference between conjunctivitis and keratitis. “The entire conjunctiva would be very, very red – so they look very similar,” Tuli says.
Experts say it typically takes a trained eye to tell the difference between conjunctivitis and keratitis. An eye doctor may use a slit lamp – a bright, high-intensity light combined with a microscope – to look more closely at the eye. With the slit lamp and dye called fluorescein, you can see damage to the cornea, notes Andrew Pucker, an assistant professor of optometry and vision science at the University of Alabama at Birmingham. That can confirm a diagnosis of keratitis.
When to Seek Medical Attention
An eye doctor, either an optometrist or ophthalmologist, will perform an eye exam and make a diagnosis. Seek medical attention right away if:
- Your vision becomes blurred or worsens.
- You have significant eye pain.
- You have extreme light sensitivity.
These may be signs of keratitis, which can cause vision loss – especially if severe. Fortunately, it’s usually treatable.
Certainly, if your symptoms aren’t going away or getting worse, or if you’re having severe pain or decreased vision, go straight to an eye care professional, says Dr. Jennifer Ling, a clinical assistant professor of ophthalmology and visual sciences at University of Iowa Hospitals & Clinics. Those wearing contacts should also heed symptoms and seek medical attention.
“It will be very hard for a layperson to distinguish what’s going on, and you really need the eye doctor to take a look and make a distinction,” Ling says. For the purposes of properly addressing the issue, it’s crucial to determine whether a person has conjunctivitis or keratitis.
Wearing contacts that aren’t properly used or cared for – like sleeping in contact lenses – is the top risk factor for developing keratitis. So make sure to tell your doctor about any symptoms if you wear contacts.
“If a contact lens wearer is having any concerning symptoms (eye pain, redness, decreased vision, discharge), the first step is to remove the contact lenses and abstain from further use until symptoms resolve or they see an eye care professional,” Ling advises.
Other causes of keratitis include:
- Eye surgery or injury.
- Bacteria like pseudomonas, a common germ found in the environment, that can cause infection. Bacteria can contaminate contact lenses, especially if they’re not properly cleaned or stored. Wearing them for a long period of time without taking them out increases the risk for infection.
- Viruses like the herpes simplex virus that also causes cold sores.
- Fungi, such as fusarium, which can cause eye infections.
- Parasites, such as acanthamoeba, a single-celled organism that can cause eye infections. As with bacteria and fungus, these parasites can also take up residence in contacts that aren’t properly cleaned and stored.
If it’s pink eye, an eye doctor can determine the cause, which can be:
- A virus, such as the adenonvirus that commonly causes colds.
- An allergen such as pollen or pet dander, in those who have allergies.
- Chemical or irritant, from air pollution (e.g. particulate matter), pool cholorine and eye makeup.
Treatment of keratitis and conjunctivitis depends on the cause.
For bacterial keratitis, the most common form of keratitis, the treatment is antibiotics. If the infection is mild, topical treatment with antibacterial drops may be enough. However, in more serious cases, oral antibiotics may be needed as well.
For other infectious forms of keratitis, treatment varies. For example, antiviral drops or medication, or comfort care, such as artificial tears, are typically recommended for viral keratitis. If the keratitis is noninfectious – caused by an injury or scratching of the cornea, such as by dirt or a contact lens – antibiotic ointment may be used to keep it from getting infected as it heals.
Viral conjunctivitis – pink eye caused by a virus, the most common form of pink eye in adults – typically resolves on its own within a few days to two weeks. Comfort care is usually all that’s recommended, such as artificial eye drops and a cold compress, like a wet washcloth.
However, based on severity, and if it’s caused by something else like bacteria, conjunctivitis may require treatment. For bacterial pink eye, which is more common in kids than adults, treatment with antibiotics is recommended.
Importantly, experts say, patients should let their eye doctors know if their symptoms persist for conjunctivitis or keratitis, especially if they last beyond two weeks. And make sure to disclose any vision concerns immediately, so that treatments can be adjusted promptly as needed.
“Keratitis again can be treated, and if treated early can have good outcomes,” Tuli says. “But if it is not treated early and gets out of control, it can cause a permanent decrease in vision or loss of vision.”
Preventing Keratitis and Conjunctivitis
Particularly for infectious forms of keratitis and conjunctivitis, the most common types, keeping your hands clean can help prevent spread and transmission.
“As with almost any communicable disease, the best thing is to wash your hands really well,” Pucker says. The Centers for Disease Control and Prevention recommends washing hands with soap and warm water. If that’s not available, use alcohol-based hand sanitizer that contains at least 60% alcohol to clean your hands, the CDC suggests.
Eye doctors also say it’s important to resist the urge to touch or rub your eyes. And, “if you’re sick stay home,” Pucker reminds.
For contact wearers, the best way to avoid bacterial keratitis, he says, “is to just keep your contact lenses clean and follow your doctor’s advice on how to care for them.” Recommended best practices include taking your contacts out before you go to bed. “There are some manufacturers that advertise that their contact lenses are safe for continuous (night and day) wear, but in general, we do not believe this is safe,” Ling says.
“People will sleep in them or wear them more or longer than they’re supposed to, or would go swimming in them or shower in them. Those are all bad ideas,” Tuli adds. “Good contact lens hygiene is a good idea.”
Above all, experts emphasize, don’t take chances with your eyes or your vision. If you have concerning symptoms, and especially if you’re experiencing any vision problems, seek medical attention right away for a thorough evaluation.