22 Causes of Red Veins in Eyes

Contact Lens Wear

Contact lenses can be irritating to the eyes, causing red veins to appear. Some common reasons contacts may irritate your eyes include:

• Poor fit
• Leaving them in too long
• Traumatic removal
• Wearing a damaged contact lens
• Poor hygiene

Sometimes contact lens complications can cause corneal abrasion—a scratch on the cornea that can then become infected and result in an infectious corneal ulcer.

Frequent Use of Eye Drops

Avoid using eye drops that include ingredients that constrict blood vessels such as tetrahydrozoline HCL. They can become less effective as you build up a tolerance to the drug, and they can cause rebound (returning) redness when the drop is stopped.

Computer Vision Syndrome

Red, dry eyes result from a lack of moisture to the eyes. Your tears work to replenish moisture to the eyes by blinking.

Blinking is one of the fastest reflexes of the body. However, people tend to blink about half as much as normal when working on a computer. This is known as "computer vision syndrome" or digital eye strain.

Lack of Sleep

Losing sleep tends to increase blood and fluid around the eyes. This makes them appear puffy and red. Lack of sleep can also lead to dry eyes.

Your eyes need rest to clean and renew. Unfortunately, when you don't get enough sleep, your eyes don't get the long rest they need for proper fluid circulation.

Swimming

Many people develop red veins in their eyes after spending time in a pool. Redness occurs when the chlorine used in many pools causes the eyes to become irritated. As with other causes of bloodshot eyes, this leads blood vessels near the eye's surface to become enlarged and dilated.

If you are prone to getting bloodshot eyes from swimming, wear swim goggles in the pool.

Smoking Cigarettes

Smoking a cigarette releases several harmful chemicals that can irritate the sensitive tissues of the eyes. It also leads to dry eye irritation, disrupting the tear film layer and leading to symptoms of eye inflammation and bloodshot eyes.

Alcohol and Cannabis

Drinking alcohol can cause some people to develop eye redness, most notably females. This is because alcohol can cause vasodilation (widening of blood vessels). 

Alcohol is dehydrating and can cause the eyes to appear red and tired. It's well known that using cannabis causes bloodshot eyes too, whether you smoke the plant or consume it as an edible.

Vasodilation and eye redness happen because substances affect the surface of the eye. In the case of cannabis, however, there's also some evidence of a pathway for the treatment of glaucoma, a pressure-related eye disorder.

Allergies

You may notice red veins in your eyes due to allergies. In addition, red eyes from allergies often burn and itch.

With allergies, the eyes become red because the blood vessels in the front part of the eye dilate and become larger. As a result, fluid accumulates and causes swelling.

Pregnancy

Pregnancy causes large changes to several hormones in the body. These shifts can cause the body to produce fewer tears, so your eyes may feel irritated or gritty. In addition, they may appear red and be sensitive to light.

Photokeratitis

Photokeratitis is a painful condition that occurs when your eyes are exposed to ultraviolet (UV) rays.

Ultraviolet rays naturally come from the sun and are also artificially produced in tanning beds. You can get photokeratitis by spending time in the sun or a tanning bed without eye protection. It can also happen when UV rays reflect off of snow or ice and into your eyes.

In addition to redness, symptoms of photokeratitis include watery eyes, blurry vision, and light sensitivity. Symptoms typically resolve within six to 48 hours, though they may be more severe if you are exposed to UV rays for a prolonged period.

Keep in mind that long-term UV exposure can also lead to increased risk of cataracts, and eye conditions including pterygium (a growth in the corner of the eyes) and pinguecula (a type of eye lesion).

Pink Eye

Pink eye (conjunctivitis) is a common cause of red veins in your eye(s). Pink eye is a swelling or infection of the clear, protective layer that covers the front part of the eye.

One small study found that 46% of red eye cases documented at a primary care clinic over a few months were caused by conjunctivitis (and another 32% were due to dry eye). Pink eye can be caused by allergies, bacteria, viruses, or toxic substances. It is usually not serious.

Pink eye is extremely contagious and can be easily transferred by touching your eyes. Avoid sharing towels or physical contact with anyone infected with conjunctivitis.

Blepharitis

Blepharitis is a common reason for painful, red-veined eyes. It is caused by impacted oil glands that can't release the oily layer of the tear film well. This leads to inflammation of the eyelid.

Common causes include:

• Poor makeup hygiene
• Decreased blinking

1. Ocular demodicosis (a mite that normally lives on human skin)

Blepharitis is not infectious and usually does not cause permanent damage to your eyesight. Blepharitis symptoms include:

• A sandy or burning sensation in your eyes
• Excessive tearing
• Itching
• Red and swollen eyelids
• Dry eyes
• Crusting eyelids

You may wake up with red, bloodshot eyes if you have blepharitis. Eyes do not produce tears when you sleep, so you could wake up with dry, red eyes due to a lack of lubricating tears.

Uveitis

Uveitis is an inflammation of the eye's uvea, the middle layer of the eyeball. This condition can occur suddenly and get worse very quickly, leading to serious vision threats. Symptoms include:

• Redness
• Pain
• Blurry vision
• Floaters
• Light sensitivity

Your healthcare provider will most likely prescribe a form of steroids to help reduce swelling. If an underlying cause of the uveitis is determined, that will be treated as well.

COVID and Red Eyes

Studies show that eye symptoms occur in about 5% of COVID-19 cases. When eye symptoms do occur, they often appear before other systemic symptoms, such as fever and headaches.

The most common eye symptoms associated with COVID-19 include:

• Bloodshot eyes
• Light sensitivity (photophobia)
• Soreness
• Itchiness

Eye symptoms typically resolve around the same time that other COVID-19 symptoms do.

Dry Eye Syndrome

Dry eye syndrome occurs when there are not enough natural tears to keep the front part of the eye moist, leading to red-veined eyes and irritation.

Dry eyes can result from:

• Staring at a computer screen for an extended amount of time
• Lack of quality sleep
• Wearing your contact lenses for too long
• Certain medications
• Hormonal changes 
• Plugged tear glands

Injury

Redness often occurs with an eye injury. Injuring your eye could be as simple as sticking yourself with a mascara wand or accidentally scratching your eye with a fingernail.

When you injure your eye, blood vessels inside the eye enlarge and dilate. This brings blood and cells to heal and repair the injury. Eye redness from an injury is a sign that something is wrong with your eye.

Corneal Ulcer

A corneal ulcer occurs when the eye's cornea becomes infected, leading to a sore on the cornea. When this happens, nearby blood vessels become enlarged and swollen. As cells rush in to help fight the infection, it can cause visible redness.

With a corneal ulcer, the nearby blood vessels enlarge to quickly get important inflammatory cells to the site. In addition to bloodshot eyes, symptoms of a corneal ulcer include:

• Pain
• Discharge
• White spot on the cornea
• Blurred vision
• Itching
• Light sensitivity

Medicated drops that are targeted to treat the cause of the underlying infection are often used to treat corneal ulcerations. The drops may be antibacterial, antiviral, or antifungal.

Steroids are not commonly started at the beginning of corneal ulcer treatment. However, your healthcare provider may prescribe them to reduce scarring and inflammation once the infection is under control.

Subconjunctival Hemorrhage

A subconjunctival hemorrhage (also known as bleeding in the eye) causes the white part of the eye to become completely red. It occurs when a blood vessel bursts underneath the conjunctiva, the transparent, clear tissue that covers the white part of the eye.

The blood has no place to go, so it spreads out. Sometimes the blood can gather so much that the eye appears swollen and pouches outward.

It usually does not cause permanent harm to the eye and is rarely painful, but one study found subconjunctival hemorrhage was common enough to be the third-leading cause of eye emergency visits. Common causes include:

• Contact lens use (primary cause in younger people)
• Eye surgery complications
• Conjunctival inflammation or tumor
• Eye trauma
• High blood pressure (typically in older adults)
• High cholesterol
• Diabetes

Acute Angle-Closure Glaucoma

Sometimes red veins in the eyes can signal a serious condition. One severe eye condition that may cause bloodshot eyes is acute angle-closure glaucoma (also narrow-angle glaucoma or closed-angle glaucoma).

This type of glaucoma occurs when the fluid pressure inside the eye rises quickly, causing:

• Sudden redness
• Severe eye pain
• Blurred vision (usually occurring in only one eye)

Episcleritis and Scleritis

Episcleritis and scleritis are two somewhat similar-looking causes of red veins in the eyes. Both are caused by inflammation, episcleritis of the thin, clear tissue layer between the conjunctiva and the deeper sclera, and scleritis of the deeper scleral blood vessels.

• Episcleritis causes mild eye pain, irritation, and eye redness. Sometimes the eyes become tender to the touch.
• Scleritis is a deeper inflammation of the eyeball's outer coat. In this condition, the eye is usually deep red and very painful, with pain sometimes radiating to the surrounding face.

Often, scleritis is caused by an autoimmune condition (rheumatoid arthritis, for example). Your healthcare provider may order blood work as part of diagnosing your condition.

Dehydration

Dehydration can lead to red eyes due to the irritation caused by dryness.

The surface of your eyes is lubricated with each blink. When the body is dehydrated it doesn't have enough water and other fluids to perform normal functions.

Fewer tears are available to lubricate the eye, causing the eyelids to rub on the cornea, creating a gritty, red-eyed irritation.

Spider Veins

Eye veins, also known as spider veins, are visible red or purple blood vessels on the surface of the eye.

Several factors contribute to the development of visible eye veins:

• Aging
• Sun exposure
• Eye strain
• Genetics
• Eye injuries

They are typically harmless but can be a cosmetic concern for some people.