The sudden appearance of a white spot on the surface of the eye is understandably alarming. Many different conditions can lead to this visual change, ranging from minor, benign growths to serious, vision-threatening infections. Self-diagnosis is unreliable and potentially harmful, as the location and nature of the spot require professional evaluation. Determining the exact cause of a white spot depends entirely on a thorough examination by an eye care professional.
Visual Clues: Location and Appearance
Identifying the precise location of a white spot is the first step in categorizing the potential cause. Spots appear on two main exterior surfaces: the cornea and the conjunctiva/sclera. The cornea is the transparent, dome-shaped outer layer covering the iris and pupil. A spot appearing on the cornea often looks hazy, gray, or white, and may cause blurred vision by obstructing the light path.
The sclera is the opaque, white part of the eye, covered by the thin, clear conjunctiva. A spot on this area typically presents as a distinct, raised bump or patch, which might be white or yellowish. The appearance of the spot itself also provides information; a clearly defined, raised bump suggests a different cause than a diffuse, cloudy area. The distinction between the cornea and the sclera guides the professional diagnosis.
Non-Urgent Explanations for White Spots
Many white or yellowish spots are benign growths resulting from environmental exposure that do not threaten vision. A common non-urgent finding is a pinguecula, a yellowish-white bump that forms on the conjunctiva, the transparent covering over the white part of the eye. This growth is typically located closer to the nose and is composed of deposits of protein, fat, or calcium. Pingueculae are caused by chronic exposure to ultraviolet (UV) radiation, wind, and dust.
Another similar condition is a pterygium, sometimes called “surfer’s eye,” which is a raised, wedge-shaped growth of fleshy tissue. A pterygium begins on the conjunctiva but can grow and extend onto the cornea, distinguishing it from a pinguecula. While both are linked to UV exposure, a pterygium can affect vision if it grows large enough to cover the central cornea, requiring monitoring. Other white spots may be scar tissue from a past, minor corneal abrasion that healed, leaving behind a small area of opacity.
Serious Causes Requiring Immediate Attention
A white spot on the cornea can signify a vision-threatening condition known as a corneal ulcer, or infectious keratitis. This is an open sore on the eye’s surface and is considered an ocular emergency because it can lead to rapid and permanent vision loss without prompt treatment. The ulcer typically appears as a localized white or gray patch on the cornea, representing active inflammation and infection.
Corneal ulcers are frequently caused by bacterial, viral, or fungal infections. Contact lens wearers are at significantly higher risk, especially those who wear lenses overnight. A corneal abrasion, or small scratch, can create an entry point for microorganisms to invade the deeper layers of the cornea and establish an infection. Symptoms accompanying an active corneal ulcer include severe pain, intense sensitivity to light, a feeling of having something in the eye, and excessive discharge.
Other serious causes of corneal clouding include severe dry eye syndrome or autoimmune disorders, which make the cornea more susceptible to breakdown. In rare cases, a white spot visible through the pupil, called leukocoria, can signal advanced cataracts or, in children, a more serious intraocular disease. Any white spot accompanied by a sudden change in vision, increasing pain, or discharge requires urgent medical intervention to preserve sight.
When to Seek Medical Care
The appearance of any new white spot warrants a professional evaluation to rule out serious underlying causes. If the spot is accompanied by “red flag” symptoms, seek immediate attention from an ophthalmologist or an emergency room. These symptoms include:
- Severe eye pain
- Persistent blurred vision
- Pus-like discharge
- Extreme sensitivity to light
These signs indicate an active infection, such as a corneal ulcer, where delay increases the risk of permanent vision damage.
If the spot is a stable, yellowish-white bump on the white part of the eye, with no accompanying pain or vision changes, it is typically less urgent but still requires a scheduled appointment. During the examination, the doctor will take a detailed history, assess vision, and use specialized equipment like a slit lamp to examine the spot closely. The doctor may also use a dye, such as fluorescein stain, to check the corneal surface for signs of an open wound or ulceration.