What’s Giving You A Red Eye? 10 Possible Causes

causes of red eyes

Bleak, blood-shot eyes sure aren’t a pretty sight, but they can also mean discomfort and pain.  Many conditions can lead to red eyes. While some are completely harmless, others might need medical attention. Here’s a look at 10 possible causes for your red eyes.

1. Eye Strain

Sometimes, the reason that your eyes look red can be as simple as eye strain. You could experience eye strain if you spend long periods looking at a digital screen – for instance, when you are constantly on the computer, work without sufficient lighting, or have light reflecting off your screen. Your eyes may also feel fatigued if your computer screen isn’t positioned properly. Most people generally find it more comfortable to view a screen at a downward angle.1 2


2. Dry Eye

Tears perform the important function of hydrating your eyes and washing away any foreign particles that get into it. However, sometimes your eyes don’t produce enough tears, and this results in dry eyes. Other than red eyes, this condition can also cause a burning, itchy, or gritty feeling in the eye. You may experience some sensitivity to light and blurred vision too. Dry eyes can develop due to age or hormonal changes. Being in a dry environment (say, due to air conditioning), overexposure to the sun, exposure to cigarette smoke, and some medications used for treating allergies and colds can also cause dry eyes.3

3. Sun Exposure

Overexposure to ultraviolet rays can burn the front surface of the eye and cause a painful inflammation similar to a sunburn on the skin. Overexposure can happen from light reflecting off snow or water, an artificial light source like a tanning bed, welding torches etc. This condition, which is called a flash burn, can cause pain, sensitivity to light, blurred vision, watering of your eyes, and a gritty feeling in the eye along with redness.4


4. Conjunctivitis

Conjunctivitis or pink eyes is a common problem that can be very contagious. If you have this condition, the clear, thin layer of tissue which covers your eyeballs and the inside of your eyelids gets inflamed, making your eyes feel gritty and look bloodshot. You may also find that your eyelashes are coated in a sticky discharge and that your eyes are watery and itchy when you get conjunctivitis. Pink eyes can be caused by viral and bacterial infections as well as irritants like dust or chlorine, or allergies (for instance, to pollen). And when it’s caused by an allergy or exposure to an irritant, it’s not contagious.5

5. Blepharitis

Blepharitis, a non-contagious disorder that causes the edge of your eyelid to become swollen and red, is usually a chronic condition which might recur repeatedly. This condition can develop as a reaction to bacteria that usually lives on your skin without causing any harm. Skin conditions like seborrhoeic dermatitis, which makes your skin flaky and oily, and rosacea, which causes a rash, can also lead to this condition by blocking glands present along your eyelid margins.


If you have blepharitis you may also see sore, itchy, reddened, and sticky eyelids and crusty eyelashes. Increased light sensitivity and a gritty, burning feeling in the eyes are also symptoms of this condition.6

6. Iritis

Your iris is the circular the part of the eyes that’s colored. The muscles of the iris control the amount of light that enters your eye by constricting and opening. Inflammation of this important component of your eye is known as iritis or anterior uveitis. It can cause your eyes to become red as well as cause sensitivity to light, blurred vision, and a headache.


Problems with the immune system and infections have been known to lead to iritis. For instance, conditions like ankylosing spondylitis, sarcoidosis, psoriasis, infection by the herpes virus, or varicella-zoster virus are associated with it. However, in many cases, a specific cause cannot be identified for this condition. 7 8

7. Subconjunctival Hemorrhage

An injury to your eye, straining, or even coughing can sometimes cause a blood vessel on the surface of your eye to burst and lead to a red patch in your eye. This condition is known as subconjunctival hemorrhage. And though it can look particularly alarming if you’re taking medication that lessens the clotting property of blood, it generally heals on its own a few weeks.9


8. Acute Glaucoma

Acute glaucoma is a condition where the pressure inside your eye suddenly increases. This can cause extremely red eyes and severe pain, as well as cloudy or blurred vision. You may also see halos around lights and feel nauseous. Glaucoma damages the optic nerve which connects your brain to your eye and is generally caused by fluid buildup in the eye which exerts pressure on the nerve. Acute glaucoma should be considered a medical emergency as it can cause loss of vision.10

9. Corneal Ulcer

An ulcer on the outer layer before your eyeball known as the cornea can make your eyes red, cause sensitivity to light, and give you a gritty feeling as though something is in your eye. These ulcers are usually caused by bacterial or viral infection. People who use contact lenses are especially vulnerable to bacterial infections while those who suffer from cold sores frequently also often get viral corneal ulcers.


10. Corneal Scratch

Sometimes a foreign particle can get in your eye and make it red and painful. If whatever’s in your eye has scratched it, that too can cause discomfort.

When To Get Medical Attention If You Have Red Eyes

Do get emergency medical help if you have the following symptoms accompanying your red eye:

  • A headache along with a sense of confusion or blurred vision.
  • You see halos around lights
  • You are vomiting or nauseous.

It’s also a good idea to speak to your doctor if:

  • You have something in your eye.
  • You’re getting a greenish or yellow discharge from your eyes.
  • You have problems with your vision or pain.
  • Your eyes have become sensitive to light.
  • Your eyes remain red for more than 2 days.11