2020–2021 BCSC Basic and Clinical Science Course™
4 Ophthalmic Pathology and Intraocular Tumors
Part I: Ophthalmic Pathology
Chapter 11: Retina and Retinal Pigment Epithelium
The term albinism refers to the congenital absence or dilution of the pigment in the skin, eyes, or both. This condition results from genetic mutations that alter or prevent the biosynthesis of melanin. True albinism is divided into oculocutaneous and ocular forms. Clinically, this distinction is somewhat helpful; however, in reality, all cases of ocular albinism have some degree of cutaneous involvement. The 2 types of albinism do have a pathophysiologic difference: in oculocutaneous albinism, transmission is commonly autosomal recessive, and the amount of melanin in each melanosome is reduced; in ocular albinism, transmission is commonly X-linked recessive, and the number of melanosomes is reduced (Fig 11-3). See BCSC Section 6, Pediatric Ophthalmology and Strabismus, and Section 12, Retina and Vitreous, for further discussion of albinism.
Figure 11-3 Albinism. A, Clinical appearance with total iris transillumination. B, Fundus photograph illustrating diffuse hypopigmentation. C, Photomicrograph illustrates lack of pigment in the iris pigment epithelium (between arrowheads), allowing visualization of the nuclei. No appreciable pigmentation is present in the iris stroma. D, Photomicrograph showing the RPE and choroid in an albino eye. There is markedly reduced pigment in the RPE cells (arrows) and no appreciable pigmentation in the choroid (asterisk).
(Parts A and B courtesy of Robert H. Rosa Jr, MD; parts C and D courtesy of Nasreen A. Syed, MD.)
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.