The white part of the eye, known as the sclera, is smooth, opaque, and white. This fibrous outer layer maintains the eye’s structure and protects its internal components. While a healthy sclera is uniformly white, various factors can lead to a change in its color, sometimes causing it to appear brown. These discolorations can range from harmless to indications of underlying health conditions that warrant medical attention.
Environmental and Benign Factors
Exposure to environmental elements and natural aging can lead to brown discoloration of the sclera. Prolonged exposure to ultraviolet (UV) light from the sun, along with wind and dust, can cause growths on the conjunctiva. One such growth is a pinguecula, which appears as a yellowish or brownish bump, often near the cornea. These are benign and usually do not impact vision.
A pterygium is a fleshy growth that can develop from a pinguecula or directly from environmental exposure. While harmless in early stages, pterygia can grow large enough to extend over the cornea, potentially affecting vision. Natural aging also contributes to changes in scleral coloration; over time, the sclera may appear darker, redder, or yellower due to physical changes and fatty deposits.
Another common cause of brown spots on the sclera are scleral nevi, often referred to as “eye freckles.” These are collections of pigmented cells, similar to moles on the skin, present from birth or developing in early childhood. Scleral nevi are harmless and do not cause symptoms, though their appearance can vary in size and color.
Underlying Medical Conditions
Brown discoloration of the sclera can signal more significant medical conditions. Jaundice, for instance, causes the whites of the eyes to turn yellow or brownish-yellow. This occurs due to bilirubin buildup, yellowish pigment from red blood cell breakdown. Liver dysfunction, bile duct obstruction, or certain blood disorders can prevent proper bilirubin processing, leading to its accumulation in body tissues, including the sclera. Scleral yellowing is one of the earliest visible signs of such issues.
Certain systemic conditions can contribute to changes in eye pigmentation. Addison’s disease, a disorder of the adrenal glands, can lead to increased melanin production throughout the body. While not exclusively affecting the sclera, this can result in generalized darkening of the skin, which may include areas around the eyes. Ochronosis is a rare genetic disorder where homogentisic acid accumulates in connective tissues. This accumulation can lead to a bluish-black or brownish discoloration, noticeable in the sclera.
Some long-term medications can cause scleral discoloration as a side effect. The antibiotic minocycline, for example, is known to induce blue-black or brown pigmentation in the eyes, including the sclera and conjunctiva. Iron overload conditions, such as hemochromatosis, can cause pigmentation. In these cases, excessive iron accumulation can cause a darkening of the skin and, less commonly, brown pigmentation of the conjunctiva.
When to Consult a Professional
While many instances of brown discoloration on the sclera are benign, it is important to seek professional medical advice. Consulting an eye care professional is recommended if the brown spot or discoloration appears suddenly or progresses rapidly. Any changes in the size, shape, or color of an existing spot should prompt a visit to a doctor.
It is important to seek medical attention if the discoloration is accompanied by other symptoms. These can include yellowing of the skin, fatigue, or abdominal pain, which may suggest liver-related issues. Vision changes, eye pain, redness, irritation, discharge, or light sensitivity alongside the brown discoloration warrant prompt medical assessment. Even without other symptoms, a consultation is advisable if there is any concern about the change in eye color. A medical professional can diagnose the underlying cause and determine the appropriate course of action.