Keratitis is inflammation of cornea, the transparent domelike portion of the eyeball in front of the iris and pupil. There are several varieties of keratitis, which can be caused by either infectious or noninfectious processes. In many cases, however, changes in the cornea induced by noninfectious keratitis predispose it to secondary infections. Often there is inflammation of both the cornea and the conjunctiva, the mucous membrane that lines the inside of the eyelid and covers the white of the eye (the sclera). In this case, the condition is called keratoconjunctivitis.
There are various types of keratitis, but most commonly it occurs after an injury to the cornea, dryness or inflammation of the ocular surface or contact lens wear. The most common infectious cause is herpes simplex virus type 1, but it can also be due to varicella zoster, which is the reactivation of chicken pox virus; and the adenoviruses that cause upper respiratory infections. Less commonly, bacteria, parasites, fungi and vitamin A deficiency can cause keratitis. Keratitis can lead to vision loss from corneal scarring.
Causes
Causes of keratitis include –
- Injury – If an object scratches the surface of one of the corneas or penetrates a cornea, keratitis without an infection may result. In addition, an injury may allow bacteria or fungi to gain access to the cornea through the damaged surface, causing infectious keratitis.
- Contaminated contact lenses – Bacteria, fungi or parasites — particularly the microscopic parasite acanthamoeba — may inhabit the surface of a contact lens or contact lens carrying case. The cornea may become contaminated when the lens is in the eye, resulting in infectious keratitis.
- Viruses – Viruses such as the herpes viruses (herpes simplex and herpes zoster) and the virus that causes chlamydia may cause keratitis.
- Contaminated water – Chemicals in water such as those used in swimming pools may irritate the cornea and weaken the delicate surface tissue of the cornea (corneal epithelium), resulting in a chemical keratitis. This is usually short-lived and may last only minutes to hours.
Bacteria, fungi and parasites in water — particularly in oceans, rivers, lakes and hot tubs — can enter the eyes when people are swimming or bathing and result in keratitis. If people are exposed to these microorganisms, a healthy cornea is unlikely to become infected. But if people have experienced some previous breakdown of the corneal epithelium, such as from wearing a contact lens too long, the cornea may be vulnerable to infection.
Risk Factors
- Use of tap water in cleaning and disinfecting contact lenses—including the lens case.
- Swimming with contact lenses in the eyes, especially in fresh water lakes and rivers. Acanthamoeba keratitis has also been isolated from virtually all water sources—from pools to hot tubs to showers.
- Failure to follow lens care instructions /poor compliance.
Reduced immunity – If the immune system is weakened due to disease or medications, people are at a higher risk of developing keratitis.
Warm climate – If people live in a warm, humid climate, they risk of keratitis is increased, particularly if plant material gets into the eyes. Plant material can scratch the corneal epithelium and chemicals from the plant can cause an inflammation, which may then lead to an infection.
Corticosteroids. Use of corticosteroid eyedrops to treat an eye disorder can increase your risk of developing infectious keratitis or worsen existing keratitis.
Symptoms
With its ability for quick repair, the cornea usually heals after most injuries or disease. However, during the healing process a variety of symptoms may be experienced, including –
- Pain
- Blurred vision
- Tearing
- Redness
- Extreme sensitivity to light
- Foreign body sensation, tearing, light sensitivity, and blurred vision.
Although these symptoms may occur with many other types of eye problems, they may indicate a more serious problem or require special treatment. Therefore, if some experience any of these symptoms, they should seek medical advice.
Complications
Potential complications of keratitis include –
- Chronic corneal inflammation
- Chronic or recurrent viral infections of your cornea
- Open sores on your cornea (corneal ulcers)
- Corneal swelling and scarring
- Temporary or permanent reduction in your vision
- Blindness
Treatment
Treatment of keratitis depends upon the cause. If there is mild injury to the cornea, such as a scratched cornea, no specific treatment is necessary. An antibiotic ointment might be prescribed. This is done mostly for comfort.
If the keratitis is caused by herpes simplex or the herpes zoster virus that causes shingles, your doctor will prescribe antiviral eye drops or an antiviral oral medication or both. Bacterial keratitis needs to be treated with antibiotics. Depending on the severity of the infection, an oral antibiotic may be prescribed along with an antibiotic ointment or eye drops.
Artificial tears for lubrication usually are effective for keratitis related to ocular dryness. Keratitis caused by an autoimmune disease is often treated with topical corticosteroid eye drops. Also treating the underlying disease helps the keratitis heal with less chance of recurrence.
Alternative Treatment
Licorice Root – Extract from the root of the licorice plant may have properties that would benefit symptoms of conjunctivitis and keratitis. Licorice has anti-inflammatory components that could reduce swelling and associated discomfort on the surface of the eyes.
Elderberry extract comes from the fruit of the elder tree. This extract has properties that help reduce inflammation. In theory, this could have some benefits to inflammation associated with conjunctivitis and keratitis.
Lysine is an amino acid that supports antibody, hormone and enzyme production. It also supports collagen formation and tissue repair. Lysine is thought to suppress blood arginine levels, thereby inhibiting herpes virus replication.
Vitamins A, C and E have antioxidant properties which fight free radicals that can damage the lens of the eye.
Astragalus is considered by many to be the most powerful immunity-boosting herb.
Bilberry extract (Vacciuium myritllus) derived from a fruit similar to the blueberry, contains active ingredients for eye health and proper vision. The berries are rich in the antioxidant anthocyanosides — the red pigments that are beneficial in ophthalmology and vascular diseases. Nicknamed “the vision herb” bilberry has a substantial body of research that confirms its benefits for human eyes.
Zinc is a mineral linked to good vision and may protect eye tissue from damaging light and inflammation. Zinc is found in healthy retinal tissue.
Lutein, a carotenoid found in dark, leafy greens, is also found in the retina of healthy eyes where it acts as a shield against harmful light and may help protect the eyes against damage from ultraviolet radiation.
Quercetin is a natural antioxidant bioflavonoid that protects cells from damage by free radicals.
Reference –
http://www.mayoclinic.org/diseases-conditions/keratitis/basics/complications/con-20035288
http://www.nature.com/eye/journal/v17/n8/full/6700616a.html
https://www.rcophth.ac.uk/wp-content/uploads/2014/08/Focus-Autumn-2013.pdf
http://bestpractice.bmj.com/best-practice/monograph/561.html
http://www.fpnotebook.com/eye/cornea/Krts.htm
http://www.omim.org/entry/148190
http://www.allaboutvision.com/contacts/acanthamoeba-keratitis.htm
http://www.cdc.gov/contactlenses/bacterial-keratitis.html
http://www.allaboutvision.com/contacts/acanthamoeba-keratitis.htm