Eye infection

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at November 28, 2016
StartDiseasesEye infection

Bacteria, viruses, and fungi can invade the body and attack the interior of the eye resulting in an eye infection. Most people have suffered from an eye infection at one time or another. Most of them are minor and tend to go away on their own. However, certain eye infections can indicate a severe underlying condition.


Definition & Facts

An infection of the eye results from an invasion by pathogenic microorganisms. According to the Centers for Disease Control and Prevention (CDC), approximately 1 million Americans suffer from eye infections every year. Eye infections can invade the following parts of the eye:

  • Sclera. This is the white part of the eye.
  • Iris. This refers to the colored part of the eye.
  • Cornea. This is the clear window on the front part of the eye. This part of the eye also plays a role in focusing light.
  • Orbit. This is a bony cave of the eye. It is also known as the eye socket.
  • Eyelids. The outer covering of the eye.
  • Nerves. Nerves of the eye carry visual information to the brain.
  • Extraocular muscles. These are the muscles that aid in eye rotation.

Symptoms & Complaints

Symptoms and complaints of eye infections commonly include the following:

Red, bloodshot eyes can result from an eye infection. This symptom is commonly associated with conjunctivitis, commonly known as pinkeye. 


Bacterial keratitis is a bacterial infection affecting the cornea. Approximately 25,000 Americans have bacterial keratitis per year. The causal bacteria are also found in the nose, mouth, and on the skin. These bacteria can spread to the eye and cause an eye infection. Pseudomonas aeruginosa is a common causal bacteria as are Streptococcus and Enterobacteriaceae. Keratitis can also be viral and can also be caused by amoebas such as Acanthamoeba.

A stye is a tender bump that often positions itself at the edge of the eyelid. It can be a result of a blocked gland or an eyelash that gets stuck in the eye which causes inflammation and infection. Staphylococcal bacteria are the most common culprit. A stye is also referred to as a chalazion. Blepharitis is a condition in which the eyelids are inflamed and it is associated with styes.

Conjunctivitis can be either bacterial or viral. The latter is associated with upper respiratory tract infections such as the common cold. Eye infections can also be caused by sexually transmitted infections such as gonorrhea, chlamydia, and herpes.

People with weakened immune systems are more susceptible to eye infections. Poor hygiene and grooming habits in regards to hand washing, application and cleaning of eye makeup, and maintenance of contact lenses can also increase one's risk of eye infection.

Diagnosis & Tests

Optometrists diagnose eye infections by mainly looking at the appearance of the eye and the outer surface of the eye. A slit lamp examination may be used to assess the structure of the eye. Dilating drops can be used to expand the pupil for a better view.

Eye discharge and pus can also be tested to detect certain organisms. Optometrists will also inquire about the patients’ medical history. If an eye infection associated with a sexually transmitted infection is suspected, the doctor may test for such underlying diseases.

Treatment & Therapy

Eye infections may require antibiotics or antiviral drugs. Broad spectrum antibiotics are administered for bacterial keratitis and bacterial conjunctivitis. Antibiotics to treat gonorrhea include ceftriaxone, doxycycline, ofloxacin, gentamicin, and fusidic acid. Erythromycin may be prescribed to treat eye infections caused by chlamydia.

Viral conjunctivitis tends to go away on its own with proper rest. People with viral conjunctivitis should wear glasses instead of contact lenses until they have recovered.

Prevention & Prophylaxis

Hand washing is crucial to prevent the spread of microorganisms that cause infection. Sharing of pillow cases, towels and makeup should be avoided to prevent the spread of bacteria and other organisms. 

Safe sexual practices can also reduce the risk of getting eye infections. People prone to eye infections should avoid wearing eye makeup on a daily basis. Being sure to wear clean makeup around the eye and removing it thoroughly before sleeping can also help prevent eye infections.

Properly cleaning and storing one's contact lenses can help prevent eye infections. It is also important to avoid touching or rubbing the eyes as this can spread bacteria and cause eye infections.