The sclera, the white part of the eye, is covered by the thin, clear conjunctiva. When this tissue develops a yellowish tint in only one eye, it can be concerning. While localized discoloration is often due to a benign cause specific to the eye’s surface, professional evaluation is warranted to ensure a deeper systemic issue is not overlooked.
Benign Localized Growths
The most frequent causes of yellowing isolated to a single eye are localized tissue changes that occur on the conjunctiva. These changes typically result from chronic exposure to environmental factors like ultraviolet (UV) radiation, wind, or dust. Since irritation may be uneven between the two eyes, the resulting growths can appear unilaterally.
One common finding is a pinguecula, which presents as a slightly raised, yellowish-white patch or bump on the sclera. This non-cancerous lesion is an accumulation of protein, fat, or calcium deposits and usually remains confined to the white part of the eye, not extending onto the cornea. A pinguecula rarely impacts vision, but it can become inflamed, leading to redness and irritation.
A pterygium, often called “surfer’s eye,” is a fleshy, wedge-shaped growth that may initially resemble a pinguecula. It begins on the conjunctiva and has the potential to spread onto the cornea. Because a pterygium contains blood vessels, it can cause significant irritation and, if it grows large enough, may distort the shape of the cornea, leading to astigmatism or blurred vision.
Temporary Discoloration from Healing
A sudden, localized yellowing can be a temporary stage in the body’s healing process following a minor trauma. This happens most commonly after a subconjunctival hemorrhage, which is essentially a bruise on the surface of the eye caused by a burst blood vessel. The initial appearance is a bright red patch, which is usually harmless.
As the body reabsorbs the pooled blood, the hemoglobin breaks down, similar to the fading of a bruise on the skin. The red color transitions, eventually taking on a temporary yellowish hue. This yellow stage is caused by metabolic breakdown products, such as bilirubin, before the discoloration fully clears, which generally occurs within one to two weeks.
Ruling Out Systemic Issues
While a single yellow eye strongly suggests a localized issue, it is crucial to rule out systemic conditions that affect the entire body. The most significant cause of generalized yellowing of the eyes and skin is jaundice, medically termed scleral icterus. Jaundice is caused by an excessive buildup of bilirubin, a yellow pigment created during the normal breakdown of old red blood cells.
Bilirubin is processed by the liver and excreted through bile, so a buildup indicates a dysfunction in this pathway. Conditions affecting the liver, such as hepatitis or cirrhosis, impair its ability to process bilirubin, leading to its accumulation in the bloodstream. Blockages in the bile ducts, often from gallstones, can also prevent proper drainage, causing bilirubin to back up.
The presence of jaundice is a serious medical concern because it points to underlying issues with the liver, gallbladder, or a blood disorder like hemolytic anemia. Although jaundice typically causes both eyes to turn yellow, systemic causes must be definitively excluded by a healthcare professional.
Immediate Steps and Medical Consultation
If you notice yellowing in one eye, monitor the symptom and check for accompanying signs. Assess the color more accurately by comparing your eyes in natural daylight, as artificial light can sometimes create a misleading yellowish cast. Do not attempt to self-diagnose or treat the discoloration with over-the-counter products, as this may delay necessary medical attention.
A prompt consultation with a healthcare provider is necessary, especially if the yellowing is accompanied by other symptoms that signal a systemic problem. Warning signs include yellowing of the skin, dark urine, pale stools, unexplained fatigue, fever, nausea, or abdominal pain. These symptoms suggest a possible issue with the liver or bile ducts that requires immediate blood tests and evaluation.
For a localized spot without other systemic symptoms, an optometrist or ophthalmologist can conduct a detailed eye examination using a slit lamp to diagnose growths like pinguecula or pterygium. If a systemic cause is suspected, your primary care physician will likely order liver function tests and blood work, and may refer you to a specialist for further investigation and management.