What causes eye infections? How many types of infections are there? Which are the most common types? Get information on time!

Eye infections often cause discomfort such as itching, irritation, redness, and pain. However, to treat them properly, it is convenient to know what type of microorganism causes them.

Symptoms such as redness, eye irritation, stinging, and pain may indicate some common eye infections. They can be due to different pathogens, such as viruses, bacteria or fungi. Although most cases evolve favorably, they can occasionally produce certain complications.

What causes eye infections? How to recognize them? What treatments to use in each case? Solving these questions is decisive for intervening in a timely manner. Therefore, below we want to detail the most relevant aspects of this type of infection.

About the eye and visual health

The eye, as you know, is an organ that serves to detect light and convert that light into electrochemical impulses that go through neurons to the optic nerve. Thus, this biological tool is essential to conceive the three-dimensional space in which we find ourselves, and to respond accordingly.

According to some empirical data, sight is the most valued sense, followed by hearing. However, there is no solid evidence to determine this. In any case, when any pathology occurs that weakens or prevents the functioning of the ocular apparatus, the symptoms are very noticeable and bothersome.

What causes eye infections?

There are various pathologies that happen to the eyes, most in association with loss of vision, such as myopia, astigmatism, cataracts, etc. These are due to internal morphological failures, which may include poor curvature or clouding of the lens.

Infections, on the other hand, have an exogenous origin, that is, they due to microscopic germs such as bacteria, viruses and even fungi. Due to the humidity of the surrounding tissue, the eyes can become good breeding grounds for pathogens.

What are the most common eye infections?

There are many types of common infections that can affect the eyes. And although they can present similar symptoms, it is necessary to establish their cause to choose an appropriate treatment. Below, we detail the main ones.


It is one of the most frequent ocular pathologies, since it has different origins and presents a very general clinical picture, which includes infection or inflammation of the connective mucous membrane.

According to the Centers for Disease Control and Prevention (CDC), conjunctivitis is usually due to two types of microorganisms. Below we detail them.

Bacteria: Bacterial conjunctivitis is due to the Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae species, among others. It can spread easily, more in unsanitary environments where multiple people share cleaning tools. Bacterial conjuctivitis is more common in children than in adults, and appears, especially, from December to April. It is characterized from the rest by suppuration of pus from the eye.

Viruses: Conjunctivitis can be caused by several different viral agents, such as adenoviruses. It is characterized by strong eye irritation that begins in one eye and quickly spreads to the other. It is also quite contagious.

There are other possible causes of conjunctivitis, such as allergies, exposure to chemicals, foreign bodies in the eye or the use of contact lenses. These are often punctual, non-contagious episodes of irritation.

Antibiotics are useful for infections of bacterial origin, but corticosteroid eye drops are the treatment of choice in cases of viral conjunctivitis or allergy caused. In any case, the choice between one option and another must be made by a doctor or ophthalmology specialist.


When it comes to more common eye infections, the stye would come in second. In general, this condition is mistaken for a parasite within the eye apparatus, but is actually accidentally caused by the staph bacteria.

Styes are due to bacterial growth that forms a small abscess in the sebaceous glands that surround different areas of the eyelid.

The general symptoms of this infection include the following:

  • A red lump on the eyelid.
  • Pain and swelling in the eyelid.
  • Excessive tearing.

Most of the time styes disappear on their own over time, but in rare cases antibiotics or even local surgery may be necessary to drain the pus from the affected area. A professional will determine this.

As always, when it comes to bacterial diseases, good hygiene is the best prevention; not touching your eyes without washing your hands is essential to avoid this type of pathology.


We move away from the world of bacteria, since keratomycosis is due to infection of the ocular cornea due to different types of fungi. This pathology is not so common in people who are not in contact with the rural environment and, therefore, it occurs especially in farmers, gardeners and construction workers.

Keratomycosis can occur from trauma that allows eye contact with contaminated plant surfaces, changes in the tear film, or the use of dirty and bad lenses.

The signs of this pathology are the following:

  • Photophobia.
  • Eye pain
  • Foreign body sensation in the eye.
  • Ulceration with concentric lines.

Because it can be confused with the aforementioned bacterial conditions, keratomycosis requires diagnosis by direct culture or PCR. Due to the nature of the infectious agent, its treatment includes the use of antifungals and, in severe cases, surgery.

Other common eye infections

Although the eye infections from above are the most common, there are others that you should consider in the presence of symptoms. Of course, it will be a doctor or ophthalmologist who gives the final diagnosis.

Blepharitis: may be due to bacteria. Refers to inflammation of the eyelids from an obstruction of the sebaceous glands. Your treatment may include corticosteroid drops or ointments and antibiotics.

Endophthalmitis: occurs from a fungal or bacteterial infection. It can cause pain, pus, sensitivity to lights, among others. Depending on its cause, antifungals, antibiotics, or other treatments may be necessary.

Uveitis: can result from a viral infection or eye injury. It does not usually cause long-term problems, but if you don’t treat it correctly it can lead to loss of vision. Treatment varies depending on its cause. Includes the use of dark glasses, eye drops, eye injections, among others.

What to remember?

The eyes can be affected by various pathogens, which generate symptoms such as redness, swelling and excessive tearing. Due to this, it is advisable to take precautionary and hygienic measures before coming into contact with the ocular surface.

Now, before the symptoms of infection, it is best to go to the doctor or ophthalmologist. The professional, after making the pertinent tests, will determine an appropriate treatment according to the cause.

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