A sudden, bright red spot appearing on the white part of your eye can be alarming. This localized patch of intense redness typically signals bleeding just beneath the surface of the sclera. While the sight of blood may look serious, the most frequent cause is a generally harmless condition that resolves without intervention. Understanding the source of this redness helps determine when a professional evaluation is necessary.
Understanding Subconjunctival Hemorrhage
The most common reason for a pronounced red spot is a subconjunctival hemorrhage (SCH), which is essentially a bruise on the eye’s surface. This occurs when a tiny, fragile blood vessel between the sclera and the overlying conjunctiva ruptures. Since the conjunctiva is a clear membrane, the blood is trapped and pools in a highly visible, bright red patch that does not spread beyond the eye’s front surface. The appearance is often dramatic because the blood is fresh and oxygenated.
SCH is typically painless, causes no discharge, and does not affect vision. The bleeding is often triggered by a sudden increase in venous pressure, such as from a forceful sneeze, severe cough, vomiting, or straining during heavy lifting. This type of hemorrhage usually requires no treatment and clears up on its own, similar to how a bruise fades. The body gradually absorbs the blood over one to three weeks, and the patch may change color to yellow or brown as it heals.
Other Causes of Localized Eye Redness
Localized redness that is not a simple broken vessel may be caused by inflammatory or structural changes on the eye’s surface. A pinguecula is a yellowish-white, slightly raised growth on the conjunctiva, often found near the nose. This growth is composed of protein, fat, or calcium deposits and can become inflamed, a condition known as pingueculitis, causing localized redness and irritation.
A pterygium is a similar, triangular, and fleshy growth, often with visible red blood vessels. The defining difference is that a pterygium can extend onto the cornea, which may distort vision or lead to astigmatism. Both growths are often associated with chronic exposure to ultraviolet (UV) light, wind, and dust.
Inflammation beneath the conjunctiva can also cause redness, such as in episcleritis or scleritis. Episcleritis involves the superficial layer (the episclera) and presents as a localized patch of bright red inflammation. This condition is generally mild, causes slight discomfort, and often resolves spontaneously within a couple of weeks.
Scleritis is a less common but more serious inflammation affecting the deeper white layer of the eye (the sclera). Scleritis often presents with a deep pain that can radiate to the face and a characteristic red-purple hue. A corneal ulcer, an open sore on the clear cornea, may appear as a white, gray, or red spot and is usually accompanied by severe pain and vision changes.
When to Seek Urgent Medical Attention
While the majority of isolated red spots are benign, the presence of certain symptoms alongside the redness suggests a more serious issue requiring prompt evaluation. You should seek immediate professional attention if the red spot is accompanied by any change in vision, such as blurriness or cloudiness.
Severe pain that feels deep, throbbing, or radiates to the face is a significant warning sign. Other concerning symptoms include sensitivity to light (photophobia) or the presence of thick discharge or pus. A medical assessment is necessary if the redness involves the area immediately surrounding your iris or pupil, or if you have experienced significant trauma to the eye. Recurrent, unexplained subconjunctival hemorrhages may also warrant a check-up, as they can indicate underlying issues like high blood pressure or a bleeding disorder.