Blue sclera is a condition where the white part of the eye, known as the sclera, appears to have a bluish, grayish, or purplish tint. The sclera is a tough, fibrous outer layer that provides structural integrity to the eyeball, protecting it from injury and maintaining its spherical shape. A blue hue can indicate various underlying factors.
What Causes the Blue Hue
The blue appearance of the sclera is primarily due to its thinness and translucency, which allows the underlying structures to become visible. The sclera is composed mainly of collagen fibers, which are normally arranged in an irregular pattern, contributing to its opaque white color. When these collagen fibers are thinner or less densely packed than usual, the dark, vascular choroid layer located beneath the sclera shows through. Essentially, the blue tint is not the color of the sclera itself, but rather the color of the underlying tissues and blood vessels visible through the translucent scleral layer.
Underlying Health Connections
Several medical conditions or factors can contribute to the thinning or increased translucency of the sclera, leading to a blue appearance. One cause is osteogenesis imperfecta (OI), also known as brittle bone disease, a genetic disorder affecting collagen production. Since the sclera is rich in collagen, a defect in its synthesis results in a thinner sclera.
Connective tissue disorders like Ehlers-Danlos syndrome (EDS) and Marfan syndrome can also cause blue sclera. These conditions involve defects in connective tissues, leading to scleral thinning.
Other factors can lead to blue sclera. Iron deficiency anemia can impact collagen fiber synthesis in the sclera, making it thinner and more translucent. Certain medications, such as long-term use of corticosteroids or minocycline, have also been reported to induce scleral discoloration. The natural aging process can cause the sclera to become thinner and more translucent over time, potentially leading to a bluish hue in older adults.
Can the Color Change or Fade
Whether the blue color of the sclera can change or fade largely depends on its underlying cause. In infants, a bluish tint is common because their sclera is naturally thinner at birth. This physiological thinness usually resolves as the child grows and their sclera thickens, often by around six months of age, causing the blue hue to disappear.
If blue sclera is linked to a treatable condition, such as iron deficiency anemia, the color may lessen or normalize once the underlying issue is addressed. For instance, iron supplementation can resolve the blue sclera associated with iron deficiency. However, when blue sclera is a manifestation of genetic conditions like osteogenesis imperfecta or Ehlers-Danlos syndrome, it is generally a persistent characteristic. These disorders involve fundamental defects in collagen or connective tissue, meaning the scleral thinness is often a permanent feature. While the intensity of the blue may vary, complete disappearance is unlikely in such cases.
When to Consult a Professional
It is advisable to seek medical consultation if blue sclera is newly observed, particularly if it appears suddenly in an adult. While some instances may be benign, a medical evaluation can help determine the underlying cause. Professional advice is especially important if the blue sclera is accompanied by other symptoms, such as bone fragility, frequent fractures, joint hypermobility, hearing loss, or unexplained fatigue.
A healthcare provider can perform a thorough examination, which may include blood tests or genetic testing, to accurately diagnose any associated conditions. Prompt diagnosis and management of any underlying health issues linked to blue sclera are important for overall well-being.