The white part of your eye has a specific medical name: the sclera. It is the tough, fibrous outer layer that covers most of the eyeball, providing structure and protection. You can see it clearly when you look in a mirror, as it surrounds the colored iris and the black pupil.
What Is the Sclera?
The sclera is the protective outer shell of the eye. It is made of dense connective tissue, mostly collagen, which makes it strong and slightly flexible. This layer maintains the shape of the eyeball, much like a sturdy frame holds a balloon in its shape.
It runs from the cornea at the front of the eye to the optic nerve at the back. The visible portion is what people commonly call the “white” of the eye. The sclera is covered by a thin, clear membrane called the conjunctiva, which also lines the inside of your eyelids.
In adults, the sclera is typically white. In children, it can appear slightly bluish because the underlying tissue is thinner and the dark layer beneath shows through. In some older adults, the sclera may take on a slightly yellow or brown tint due to sun exposure or the natural accumulation of fat and other substances over time.
What Does the Sclera Do?
The sclera has several important jobs. Its primary role is structural. It keeps the eye from collapsing and maintains the internal pressure needed for clear vision.
It also serves as an attachment point for the six extraocular muscles that move your eye in different directions. These muscles pull on the sclera to rotate the eyeball up, down, and side to side.
Because the sclera is opaque, it blocks light from entering the eye except through the cornea and lens at the front. This ensures that light reaches the retina in a controlled way, which is essential for forming sharp images.
The sclera also protects the delicate internal structures of the eye, including the retina, lens, and vitreous humor, from injury and infection.
What Can Change the Color of the Whites of Your Eyes?
A healthy sclera is white. When its color changes, it can be a sign of an underlying health condition. Some changes are harmless, while others require medical attention.
Yellow Whites (Jaundice)
If the whites of your eyes turn yellow, this is often a sign of jaundice. Jaundice occurs when there is too much bilirubin in the blood. Bilirubin is a yellow pigment produced when red blood cells break down. The liver normally processes and removes bilirubin, but when the liver is damaged or blocked, bilirubin builds up and stains the tissues, including the sclera.
Jaundice can be caused by liver conditions such as hepatitis, cirrhosis, or a blocked bile duct. It can also result from rapid breakdown of red blood cells, a condition called hemolysis. If you notice a yellow tint in your eyes, especially if it is new, see a doctor promptly.
Red or Bloodshot Eyes
Redness in the whites of the eyes is usually caused by dilated or broken blood vessels in the conjunctiva. This can happen from lack of sleep, allergies, dry air, smoke, or eye strain. A subconjunctival hemorrhage is a broken blood vessel that causes a bright red patch on the white of the eye. It looks alarming but is usually harmless and clears up on its own within a week or two.
However, redness combined with pain, light sensitivity, or blurred vision can indicate a more serious condition such as uveitis, scleritis, or an infection. These require prompt evaluation by an eye care professional.
Blue or Gray Whites
A bluish tint to the sclera can occur when the sclera is thinner than normal, allowing the underlying dark tissue to show through. This is seen in some genetic conditions, such as osteogenesis imperfecta, which affects collagen production. It can also appear in certain forms of anemia or as a normal variation in some people.
If you have always had a bluish tint to your eyes, it is likely harmless. If the color change is new, discuss it with your doctor.
Common Conditions That Affect the Sclera
Several conditions can directly affect the sclera. Knowing the difference between a minor irritation and a serious problem is important.
Scleritis
Scleritis is inflammation of the sclera itself. It is a serious condition that causes deep, severe eye pain, redness, and sometimes vision loss. Scleritis is often associated with autoimmune diseases, such as rheumatoid arthritis or lupus. It requires immediate medical treatment, usually with prescription anti-inflammatory medications.
Episcleritis
Episcleritis is inflammation of the episclera, the thin layer between the sclera and the conjunctiva. It is much milder than scleritis. It causes localized redness and mild discomfort but rarely affects vision. Episcleritis often resolves on its own or with artificial tears, though it can recur.
Pinguecula and Pterygium
A pinguecula is a small, yellowish bump on the conjunctiva near the cornea. It is caused by sun exposure and dry eyes. It is usually harmless and does not require treatment unless it becomes inflamed.
A pterygium is a fleshy, triangular growth of tissue that extends from the conjunctiva onto the cornea. It can cause irritation, redness, and, if it grows large enough, blurred vision. Surgery is an option if the growth interferes with vision, though it can recur after removal.
How to Keep the Whites of Your Eyes Healthy
Keeping your sclera healthy is mostly about protecting your eyes from damage and maintaining overall health.
- Wear sunglasses that block ultraviolet (UV) light. UV exposure can damage the conjunctiva and contribute to growths like pinguecula and pterygium.
- Stay hydrated. Dehydration can lead to dry eyes, which makes the whites look red and irritated.
- Get enough sleep. Sleep deprivation causes blood vessels in the eyes to dilate, making them look red.
- Take breaks from screens. Prolonged screen use can cause eye strain and dryness. Follow the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds.
- Do not smoke. Smoking increases the risk of many eye conditions, including dry eye and macular degeneration.
- Eat a balanced diet. Nutrients like vitamin C, vitamin E, zinc, and omega-3 fatty acids support eye health generally.
If you notice persistent changes in the color of your sclera, new pain, or vision changes, do not wait. An eye exam can determine whether the issue is minor or a sign of something more serious.
When to See a Doctor About Your Eyes
Not every change in the whites of your eyes is an emergency, but some symptoms warrant a call to a doctor or eye care specialist.
See a doctor promptly if you have:
- Yellowing of the whites of the eyes
- Severe or persistent eye pain
- Sudden vision loss or blurred vision
- Redness that does not improve after a few days
- Eye injury that affects the sclera
- Swelling or bulging of the eye
These symptoms can point to conditions that need treatment, such as infection, inflammation, or elevated pressure inside the eye. Early attention can prevent complications.
Frequently Asked Questions
What is the medical term for the white of the eye?
The medical term is the sclera. It is the tough, white outer layer that covers most of the eyeball.
Why are the whites of my eyes yellow?
Yellowing of the sclera is called jaundice, and it usually indicates a problem with the liver or bile ducts. See a doctor to determine the cause.
Can the whites of your eyes change color permanently?
Most color changes are temporary, such as redness from irritation. However, long-term yellowing from liver disease or gray-blue tint from thinning of the sclera can persist.
Is a red spot on the white of the eye dangerous?
A bright red spot is often a broken blood vessel, called a subconjunctival hemorrhage, which is usually harmless and heals on its own. If it comes with pain or vision changes, see a doctor.
