Eye infections: 5 serious causes and 4 usual causes of your red eye

By MedDigester Doctors on July 22, 2023

Five serious causes of red eye

1-Corneal ulcer and contact lens-related red eye

A corneal ulcer is a condition that affects the clear front part of your eye, known as the cornea. It occurs when a sore or lesion develops on the cornea, which can be caused by various factors such as infection, injury, or prolonged use of contact lenses.

Corneal ulcers can be a serious condition that requires prompt medical attention to prevent complications and vision loss.

People who wear contact lenses are more likely to get corneal ulcers. This risk is 10 times higher if you use extended-wear (overnight) soft contacts.

Bacteria on the lens or in your cleaning solution could get trapped under the lens. Wearing lenses for long periods can also block oxygen to your cornea, raising the chances of infection.

Scratches on the edge of your contact might scrape your cornea and leave it more open to bacterial infections. Tiny particles of dirt trapped under the contact could also scratch your cornea

human eye with corneal ulcer seen by eye staining
corneal ulcer seen by stain, Yoanmb, CC BY-SA 4.0, via Wikimedia Commons

The main symptoms of corneal ulcer include

  • eye pain
  • eye redness
  • eye tearing
  • sensitivity to light.
  • blurred vision,
  • discharge from the eye,
  • and the feeling that there is something in your eye.
  • A round white spot on your cornea
Pink eyeCorneal ulcer
itchingPain(something in your eye)
wateringblurred vision
dischargesensitivity to light
a gritty feelingExcessive watering
 A round white spot on your cornea

These symptoms can be very uncomfortable and may affect your ability to carry out your daily activities, If you suspect that you have a corneal ulcer, it is important to seek medical attention as soon as possible.

Treatment for corneal ulcers may include prescription eye drops or ointments to control infection and promote healing according to the cause which may be anti-bacterial, anti-viral, or anti-fungal. In some cases, oral antibiotics or antiviral medications may also be necessary

If you are a contact lens wearer you will be advised when you will be able to start wearing lenses again by your doctor or optometrist.


Scleritis is an inflammatory disease that affects the white outer layer of your eye, called the sclera. It is a rare condition that can be quite painful and can lead to serious complications if left untreated.

Scleritis is often caused by an underlying autoimmune disease, such as rheumatoid arthritis or lupus. Sometimes, it can also be caused by an infection or injury to the eye.

human eye with red digested scleral vessels
Kribz, CC BY-SA 3.0, via Wikimedia Commons

The main symptoms of scleritis include

  • severe eye pain which may radiate to the forehead and jaw.
  • Eye redness,  occasionally changing to a purple hue. Redness may not always be present.
  • blurred vision,
  • sensitivity to light,
  • and a feeling of pressure in the eye.
Pink eyeScleritis
rednessRedness (changing to a purple hue)
itchingsevere eye pain
wateringblurred vision
dischargesensitivity to light
a gritty feelingHistory of autoimmune disease

If you experience any of these symptoms, it is important to seek medical attention right away. Your doctor will perform a thorough examination of your eye to determine if you have scleritis and what type of treatment is needed.

The initial treatment is usually with nonsteroidal anti-inflammatory drugs. Most patients respond well to this treatment. Some patients require stronger immunosuppression treatment, such as steroids tablets, or alternative immunosuppressive medications

3-Orbital Cellulitis

Orbital cellulitis is a medical condition that affects the tissues around the eye socket, causing inflammation and infection. It typically occurs when bacteria from a sinus infection or dental abscess spread to the eye socket, leading to an infection. Other causes may include injury to the eye or surgery.

Jonathan Trobe, M.D., CC BY 3.0, via Wikimedia Commons

The symptoms of orbital cellulitis can vary depending on the severity of the infection. Some common signs include

  • pain and swelling around the eye,
  • redness and tenderness,
  • fever
  • difficulty moving the eye.

 In more severe cases, patients may experience

  • vision problems,
  • double vision,
  • eye protrusion.

Increased orbital pressure can cause irreversible loss of vision by obstruction of the optic nerve or retinal blood supply.

Treatment for orbital cellulitis typically involves antibiotics to fight the infection. In severe cases, hospitalization and intravenous antibiotics may be necessary. Pain relievers may also be prescribed to manage discomfort. In some cases, surgery may be required to drain pus or relieve pressure on the eye socket.


Endophthalmitis is an inflammation of the internal eye tissues, most commonly caused by an infection

human eye endophthalmitis with pus in the anterior chamber behind cornea
pus behind cornea in endophthalmitis, Imrankabirhossain, CC BY-SA 4.0, via Wikimedia Commons

this is normally a post-operative infection that occurs within the first 2 weeks of surgery and can rapidly cause blindness

  • There is a history of recent surgery, trauma, intravenous drug use, or immune compromise.
  • markedly reduced vision,
  • significant pain/headache,

you could be admitted into a hospital for more intensive treatment such as intravenous antibiotics.

5-Anterior uveitis

Anterior uveitis is a condition where the middle layer of the eye, called the uvea, becomes inflamed. This can cause pain, redness, and sensitivity to light. It’s important to seek medical attention if you suspect you have anterior uveitis, as prompt treatment can help prevent complications and preserve your vision.

red human eye with anterior uveitis
Jonathan Trobe, M.D., CC BY 3.0, via Wikimedia Commons

The main symptoms of anterior uveitis include

  • eye pain (usually a dull ache in or around your eye)
  • eye redness
  • sensitivity to light (photophobia).
  • blurred vision
  • small shapes moving across your field of vision(floaters).
  • a feeling of pressure in the eye.
Pink eyeAnterior uveitis
itchingdull aching eye pain
wateringblurred vision
dischargesensitivity to light
a gritty feelingfloaters

These symptoms can develop suddenly or gradually and may affect one or both eyes. If you experience any of these symptoms, it’s important to see an eye doctor as soon as possible.

The main treatment for anterior uveitis involves reducing inflammation in the eye. This may involve using eye drops or oral medications, such as corticosteroids. Your eye doctor may also recommend wearing sunglasses or an eye patch to help alleviate symptoms.

It’s important to follow your doctor’s instructions carefully and attend any follow-up appointments to monitor your progress.

In some cases, surgery may be necessary to treat complications or manage severe cases of anterior uveitis.

Four Usual causes of red eye include:


Conjunctivitis, also known as pink eye, is a common eye condition that can cause redness, itching, and discharge in one or both eyes.

It is caused by inflammation of the conjunctiva, which is the thin, clear tissue that covers the white part of the eye and the inner surface of the eyelid.

There are several possible causes of conjunctivitis, including viruses, bacteria, allergies, and irritants such as smoke or chemicals.

Viral conjunctivitis is the most common type and is highly contagious, often spreading from one eye to the other or from person to person through contact with infected eye secretions.

Bacterial conjunctivitis is less common but can also be contagious and may require antibiotics to treat.

pink eye with red conjunctiva
pink eye, Public domain, via Wikimedia Commons

The main symptoms of conjunctivitis include

  • eye redness,
  • eye itching
  • eye-watering
  • discharge from the eye. The discharge may be watery or thick and yellow or green in color, depending on the cause of the infection.
  • a gritty feeling in the eye.

Treatment for conjunctivitis depends on the cause of the infection.

Viral conjunctivitis usually clears up on its own within a week or two, but you can relieve symptoms with warm compresses and over-the-counter eye drops or ointments.

Bacterial conjunctivitis may require antibiotic eye drops or ointments prescribed by your doctor.

Allergic conjunctivitis can be treated with antihistamines or other allergy medications. It is important to follow your doctor’s instructions for treatment and avoid touching your eyes or sharing towels or other personal items with others to prevent the spread of infection.


Blepharitis is a common and usually harmless condition that causes inflammation of the eyelids. It can occur in people of all ages and is often caused by bacteria or an overgrowth of normal skin flora on the eyelids.

Other possible causes include allergies, hormonal changes, and certain skin conditions like rosacea.

eye with anterior blepharitis with upper eyelid lashes scaling and crusting
crusting or flaking skin around the eyelashes, Imrankabirhossain, CC BY-SA 4.0, via Wikimedia Commons

 The main symptoms of blepharitis include

  • redness and swelling of the eyelids.
  • itching or burning sensation.
  • a feeling of grittiness or irritation in the eye.
  • crusting or flaking skin around the eyelashes.
  • eyelids sticking together in the morning when you wake up.
  • eyelashes may become misdirected and grow inwards towards the eye.
  • In severe cases, blepharitis can lead to vision problems, such as blurry vision or sensitivity to light.

Treatment for blepharitis usually involves a combination of self-care measures and medication. To manage the symptoms, patients may be advised to use warm compresses or wash their eyelids with a gentle cleanser to remove any crusting or debris.

In some cases, antibiotics eye drops may be prescribed to help reduce inflammation and prevent infection. In addition, it may be helpful to avoid using eye makeup or contact lenses until the symptoms have resolved.


Dacryocystitis is a condition that affects the tear ducts in your eyes. The tear ducts are small tubes that drain tears from your eyes into your nose. When these tubes become infected or blocked, it leads to dacryocystitis.

This condition can be caused by a variety of factors, including eye infections, allergies, and structural abnormalities in the tear ducts.

The main symptoms of dacryocystitis include

  • pain, redness, and swelling around your tear duct.
  • excessive tearing, discharge from your eye,
  • and a feeling of pressure in your eye.

In severe cases, you may develop

  • a fever and feel generally unwell.

The treatment for dacryocystitis depends on the severity of your symptoms. Mild cases may be treated with warm compresses and antibiotics, while more severe cases may require surgery to remove the blockage in your tear ducts.


A stye is a small, painful lump that can appear on your eyelid. It’s caused by a bacterial infection, and it’s quite common, especially in adults.

The good news is that most styes will go away on their own within a week or two. However, if your stye is very large or causing a lot of pain, you should see a doctor.

Sometimes people get confused between a stye and a different eye problem called a chalazion. A chalazion also causes a lump on your eyelid, but it’s not caused by an infection, and it’s not painful. Instead, it can last longer than a stye but is not tender or painful.

stye, Andre Riemann, Public domain, via Wikimedia Commons


usually only affects 1 eye, but it’s possible to have more than 1 at a time.

  • A small, red lump on the inside or outside of your eyelid
  • Pain or tenderness in the affected area
  • Swelling of the eyelid
  • Discomfort when blinking or touching your eye
  • Watery or crusty discharge from your eye

It’s probably not a stye if:

  • there’s no lump – if your eye or eyelid is swollen, red, and watery it’s more likely to be conjunctivitis or blepharitis
  • the lump is hard but not very painful – it’s more likely to be a chalazion

How you can treat a stye yourself

Apply a warm compress: Soak a clean washcloth in warm water and place it over your affected eye for 5-10 minutes, several times a day. The warmth can help reduce swelling and discomfort and may help the stye to open and drain on its own.

Clean your eyelid: Gently clean your affected eyelid with mild, fragrance-free soap and water. Be careful not to rub or irritate the stye.

Avoid wearing makeup: While you have a stye, it’s best to avoid wearing eye makeup or contact lenses, as this can increase your risk of infection and may worsen your symptoms.

Don’t squeeze or pop the stye: As tempting as it may be, squeezing or popping a stye can make the infection worse and may cause it to spread. Instead, let the stye heal on its own.

Wash your hands often: To prevent the infection from spreading, be sure to wash your hands often and avoid touching your eyes.

MedDigester Doctors depend on high-quality medical evidence as peer-reviewed studies, academic research institutions, and medical associations. We don’t use low-quality or tertiary references.

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• The Royal Children’s Hospital. (2022). Acute eye injury.

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• Adam R. Sweeney, MD. (2023). Stye.

• Boyd,K. (2022). What Is Cellulitis?

• James Garrity , MD. (2022). Dacryocystitis.