Eye Infections: A Guide to Keratitis, Pink Eye (Conjunctivitis) and More

eye infections - bacteriaEye infections are a result of invasion of any part of the eye by disease-causing microorganisms. These include certain pathogens that can invade the eyelid, the conjunctiva, the cornea and, in severe and serious cases, inner parts of the eye as well. Eye infections can affect one or both eyes. Although an eye infection can seem mild, it is important to get proper diagnosis and treatment to prevent potentially serious injury to the eye.

Types of Eye Infections

Pink Eye or Conjunctivitis – In the Western world, conjunctivitis is the most common eye infection. Usually caused by bacteria or viruses, the conjunctiva, which is a thin, moist membrane, becomes inflamed. Conjunctivitis is usually highly contagious but also usually resolves without severe complications.

Keratitis – Keratitis is inflammation of the cornea. Certain types of pathogens can invade the cornea. These types of infections are more difficult to resolve than conjunctivitis. They require urgent care to prevent vision loss due to corneal scarring. Keratitis has many causes.

Amoebic Keratitis – Amoebic keratitis is usually caused by Acanthamoeba. Contact lens wearers are particularly vulnerable to this infection because Acanthamoeba is commonly found in both tap water and swimming pools. Rinsing contact lenses or cases with tap water or swimming in contact lenses can lead to infection by Acanthamoeba. Several treatment regimens exist for Acanthamoeba but infections can be difficult to cure.

Bacterial Keratitis – Bacterial keratitis can be caused by injury or by wearing contact lenses. Injury usually leads to invasion by Staphylococcus aureus. Contact lenses can transfer Pseudomonas aeruginosa. Pseudomonas contains enzymes that can digest the cornea.
Fungal Keratitis – Fungal keratitis is caused by Fusarium. It has been linked to the use of improperly prepared contact lens solution. It is also difficult to cure.

Viral Keratitis – Viral keratitis is usually caused by a herpes simplex or herpes zoster infection. In the case of a herpes simplex infection, this can lead to the formation of ulcers that cause permanent vision loss.

Onchocercal Keratitis – Called “river blindness” because the flies that transmit this pathogen are found in wet areas, this form is caused by infection with O. volvulus, a common pathogen in certain parts of Africa.

Trachoma – Caused by Chlamydia trachomatis, trachoma is almost unheard of in the United States, but it is a leading cause of blindness in many underdeveloped regions. The bacteria are carried by flies. Once the eye is infected, the bacteria inhabit the underside of the eyelid where they cause inflammation and scarring. The scarring causes the eyelashes to grow inwards toward the eye. They then scrape the cornea which is how blindness is caused. It has to be treated aggressively with oral antibiotics.

Endophthalmitis – When an infection reaches the interior of the eye, usually as a result of injury or surgery, it can cause rapid blindness and needs emergency treatment.


Symptoms of an eye infection include redness, pain, discharge, watery eyes, itching, swelling, dryness, blurriness and sensitivity to light. Most commonly, redness accompanied by thick yellow discharge occurs with eye infections.


Prognosis depends on the type of infecting organism and the stage of disease. All eye infections respond better to prompt treatment.


Treatment hinges on using antibiotics, antivirals or antifungals to eliminate the invading pathogen. In the case of viruses, many infections will resolve on their own. An eye doctor may also give a steroid treatment to reduce inflammation and to prevent scarring, or eye drops that contain a lubricant to minimize irritation. Washing the eyes gently with warm water can be helpful. And so can the use of baby shampoo, which contains long chain surfactants that can prevent bacteria from reproducing as easily.

It can also be helpful to take immune-enhancing supplements to aid the body’s own ability to fight infection. Mushrooms contain beta-glucans, which increase the body’s number of natural killer cells. Colostrum contains immunoglobulins which help fight off disease, and herbs such as astragalus and echinacea also increase the potency of the immune system.
In addition, avoiding foods that reduce immune function is important. Sugar, in particular, is a potent immune system inhibitor. Eating half of a Snickers bar reduces the average person’s white cell count by half for several hours. Refined carbohydrates turn into sugar very quickly in the body so they should also be avoided, as well as trans-fats and toxic oils, found in fried foods and chips.

Homeopathic eye drops and well-researched nutrients that support eye health can also be helpful.


Like any infection, the number one rule of prevention is good hygiene. Taking care to thoroughly wash the hands before touching the eyes is very important. Because the eyes are a moist, sensitive tissue without the protection of skin, it is very easy to transplant microorganisms into them. The standard hand washing rule is to use warm water and soap and to continue rubbing the hands for as long as it takes to repeat the alphabet. This is especially important when passing through well-trafficked areas. Be extra careful if you are in contact with a person who has visible signs of an eye infection. If it is a family member, keep their clothing and linen separated until the infection heals.

If you visit an underdeveloped country and begin to notice eye problems, seek immediate treatment, as many of the pathogens that reside in these areas can have a deadly impact on vision.
Contact lens wearers need to be particularly concerned about the possibility of acquiring an eye infection. It is important to follow all safety precautions for the use of contact lenses and to use extra scrutiny when purchasing a contact lens fluid. People who wear disposable daily contact lenses are at the lowest risk for infection since their lenses are not repeatedly transferred from eye to case and back again. Wearing lenses for extended periods of time increases risk of infection as well, as does sleeping in contact lenses, even if they are the type that is approved for sleep.