What causes the sclera (white part of the eyeball) to be brown?

From the Guidelines

Brown discoloration of the sclera is typically caused by melanin deposition, a condition that can be congenital or develop due to various factors such as aging, sun exposure, or certain medications. When considering the cause of brown sclera, it's essential to evaluate the potential underlying factors.

• Congenital conditions, such as ocular melanosis or scleral melanocytosis, can cause brown discoloration of the sclera, particularly in individuals with darker skin tones 1.
• Aging and prolonged sun exposure can also contribute to melanin deposition in the sclera.
• Certain medications, such as minocycline or chlorpromazine, have been known to cause pigment deposition, leading to brown sclera.
• Underlying health conditions, like Addison's disease, hemochromatosis, or alkaptonuria, can also cause scleral discoloration. It's crucial to have any changes in eye color evaluated by an ophthalmologist to rule out more serious conditions like ocular melanoma. The discoloration occurs because melanocytes (pigment-producing cells) in the eye produce excess melanin that accumulates in the scleral tissue. No treatment is typically needed for benign scleral pigmentation, but addressing any underlying cause may prevent further discoloration. In the context of real-life clinical medicine, it's essential to prioritize a thorough evaluation to determine the cause of brown sclera and provide appropriate management to prevent potential complications.

From the Research

Causes of Brown Sclera

The sclera, also known as the white part of the eyeball, can appear brown due to various conditions. Some of the possible causes include:

• Melanosis, which is a condition characterized by an abnormal accumulation of melanin in the sclera and other parts of the eye 2
• Oculodermal melanocytosis (ODM), a rare disease that causes hyperpigmentation of the facial skin and several parts of the eye, including the sclera 3
• Congenital ocular melanocytosis, a condition that affects the episclera and sclera, causing grayish-blue pigmentation 4, 5
• Acquired melanosis, which can be caused by irradiation, hormonal changes, chemical irritation, or chronic inflammatory conjunctival disorders 2

Associated Conditions

These conditions can be associated with other ocular and systemic disorders, such as:

• Glaucoma, which can be caused by angle abnormalities or mechanical occlusion by melanocytes in an open irido-corneal angle 3, 5
• Uveal melanoma, which has a higher incidence in patients with oculodermal melanocytosis and congenital ocular melanocytosis 3, 4, 5
• Iris heterochromia, which is a common presenting sign of oculodermal melanocytosis 3, 5

Diagnostic and Treatment Approaches

The diagnosis and treatment of these conditions require a comprehensive ophthalmological examination and may involve:

• Biopsy to grade the disease and direct further treatment 2
• Routine ophthalmological examination to monitor for glaucoma and melanoma 3
• Therapeutic modalities to manage the underlying condition and prevent complications 2