From the Guidelines
In individuals with albinism, the defective layer is the retina, specifically the retinal pigment epithelium, which is responsible for producing melanin, as evidenced by the association between albinism and disorders related to abnormal retinal function, such as keratoconus 1.
Pathogenesis of Keratoconus in Albinism
The pathogenesis of keratoconus in albinism is thought to be related to the degradation of corneal collagen, altered enzyme activities, and oxidative stress, which can lead to thinning of the cornea 1.
- Altered enzyme activities, such as increased matrix metalloproteinase levels and decreased tissue inhibitor of metalloproteinase, have been demonstrated in keratoconic corneas compared to normal corneas 1.
- Oxidative stress and inflammatory mediators, such as interleukin-6, TNF-alpha, and MMP-9, may also contribute to keratocyte apoptosis and decreased keratocyte cell density associated with keratoconic corneas 1.
Clinical Implications
The association between albinism and keratoconus highlights the importance of regular eye exams and monitoring for individuals with albinism, as early detection and treatment of keratoconus can help prevent vision loss and improve quality of life 1.
- Management of keratoconus in individuals with albinism may involve corneal cross-linking, intracorneal ring segments, or other surgical interventions to stabilize the cornea and improve vision 1.
- Additionally, protecting the skin and eyes from sun damage and addressing associated ocular issues, such as photophobia and nystagmus, are crucial for overall management of albinism 1.
From the Research
Defective Layer in Albinism
The question of which layer is defective in albinism can be addressed by considering the role of melanin in the skin, hair, and eyes.
- Melanin is produced by melanocytes in the skin and hair follicles, and by the retinal pigment epithelium in the eyes.
- In albinism, the defect lies in the production or distribution of melanin, leading to a reduction or absence of pigmentation in the affected tissues 2, 3.
- The specific layer that is defective in albinism is the melanosome, which is the organelle responsible for melanin production and storage in melanocytes 4.
- Defects in the melanosome can lead to various forms of albinism, including oculocutaneous albinism (OCA) and ocular albinism (OA) 3, 4.
- In the eyes, the defective layer is the retinal pigment epithelium, which is responsible for producing melanin and supporting the development of the retina 5.
- The lack of melanin in the retinal pigment epithelium can lead to abnormalities in the development of the visual pathway, including foveal hypoplasia and chiasmal misrouting 5, 4.