Why Does a Blind Eye Turn White? Understanding Phthisis Bulbi and Its Causes
When a blind eye turns white, it may be a sign of a condition known as phthisis bulbi. This transformation occurs as the eye undergoes a series of changes following severe ocular damage, disease, or prolonged disuse, leading to the eye losing its natural color and transparency, resulting in a white or opaque appearance. Understanding the underlying process of phthisis bulbi can shed light on why a blind eye may develop this characteristic white hue.
Ocular Atrophy and Tissue Degeneration
Phthisis bulbi is characterized by progressive atrophy and degeneration of the eye’s tissues, including the cornea, iris, lens, and retina. Following significant trauma, infection, severe inflammation, or sustained lack of adequate blood supply to the eye, the ocular structures begin to deteriorate, leading to shrinkage, loss of function, and changes in pigmentation. As the eye’s tissues break down and lose their normal structure and function, the eye may appear shrunken, opaque, and devoid of its usual coloration.
Changes in Intraocular Pressure
In cases of phthisis bulbi, the balance of intraocular pressure within the eye is disrupted, resulting in alterations in the eye’s dimensions and shape. The eye may become smaller, softer, and more prone to collapse as the internal structures degenerate and lose their integrity. These changes in intraocular pressure contribute to the eye’s altered appearance and the development of a white or whitish-gray hue due to the loss of normal tissue architecture and vascularity.
Fibrotic and Scar Tissue Formation
As the eye undergoes progressive degeneration and atrophy, fibrotic tissue and scar formation occur within the intraocular space, replacing healthy ocular structures with nonfunctional, collagen-rich tissue. This fibrotic remodeling contributes to the loss of transparency and color in the eye, creating a white or opaque appearance as the once-vital tissues are replaced by fibrous, avascular scar tissue. The presence of fibrotic changes further contributes to the visual changes observed in a blind eye affected by phthisis bulbi.
Vascular Changes and Ischemia
In advanced cases of phthisis bulbi, vascular changes and ischemia, or inadequate blood supply, play a significant role in the eye’s transformation. Reduced blood flow to the eye tissues leads to ischemic damage, tissue death, and the formation of avascular regions within the eye. As the blood vessels in the eye become compromised and fail to deliver nutrients and oxygen to the ocular structures, the eye loses its vitality, becomes dehydrated, and takes on a whitish appearance due to the absence of healthy blood flow and perfusion.
Corneal Opacification and Scleral Thinning
The cornea, the transparent outer layer of the eye responsible for focusing light onto the retina, may undergo opacification and clouding as a result of phthisis bulbi. Loss of corneal transparency further contributes to the eye’s white or opaque appearance, obscuring the underlying structures and impairing visual clarity. Additionally, scleral thinning and weakening may occur, leading to changes in the eye’s external appearance and contributing to the overall whitening of the eye in cases of severe ocular damage and degeneration.