- Allergies: Not only can an allergic reaction make your eyes feel bad—think itchy, tender, and watery—but allergies also trigger a blotchy kind of redness, which only becomes worse if you scratch your eyes. “Allergic reactions occur when the body’s natural immune system overworks or has an excessive response to a harmless stimulus,” says Dr. Lee. Almost anything can set off a reaction, but the most common allergens are dust, pollen, pet dander, and detergent.
- Pink eye: Pink eye is the non-medical term for conjunctivitis—a bacterial, viral, or allergy-induced infection that leaves one or both eyes bright red, swollen, teary and itchy, says Dr. Lee. It’s easily spread, unfortunately, and though it rarely becomes serious, a bout of conjunctivitis can keep you away from work for several days and turn your eyes into goopy, pinkish-red messes.
- Too much alcohol: If you’ve ever had one too many drinks and noticed at the time or the next day that your eyes sported bright red spider veins in them, then you’ve experienced alcohol’s effect on the eyes. Here’s what happens: Alcohol causes the tiny blood vessels on the eyes to dilate—so more blood flows through them. The more you drink, the more visible and red they appear against the whites of your eyes, says Dr. Lee.
- Too little sleep: Tired eyes tend to be bloodshot eyes. That’s because a lack of sleep can decrease the amount of oxygen that reaches your eyes, which in turn causes blood vessels in them to dilate and appear red. Another factor that leads to redness comes into play as well. “If your eyes are kept open for a long time because of lack of sleep, it prevents the cornea (the surface of your eye) from being well lubricated, and this can cause dryness and redness,” says Dr. Lee. “The best way to calm them would be to get more sleep, and use artificial tears and cool compresses to ease the discomfort.”
- A stye: A stye is a small red bump that forms on your eyelid or bottom edge of your eye after an oil gland there becomes plugged up. You could have just one or several, and each will resemble a pimple or boil. One of the first signs is redness, along with swelling and sensitivity. They’re caused by bacteria and almost everyone will have them at some point.
- Contact lens irritation: Contact lenses can prevent enough oxygen from reaching your eyes, leaving you with bloodshot and irritated peepers, says Dr. Lee. “If the lenses are worn too long or worn while sleeping, they can cause redness, infections, and in worst-case situations corneal ulcers.”
- A subconjunctival haemorrhage: A subconjunctival haemorrhage happens when a blood vessel just under the eye surface breaks, and blood gets trapped and forms a bright red patch in the white of your eye. It’s a common injury and though the haemorrhage looks serious, it won’t likely affect vision or cause any pain, discharge, or swelling.
- Glaucoma: Glaucoma is actually a series of diseases that damage the optic nerve (the nerve that connects the retina of the eye to the brain), often when too much pressure is put on the eye due to fluid build-up. One of the first signs of one type of glaucoma, called acute angle-closure glaucoma, is redness, according to the Mayo Clinic. Other signs include blurred vision, seeing halos around lights, and pain in the eyes.
