Albinism is characterized by absent or decreased skin pigment and can affect the eyes, hair, and skin. It is caused by mutations that impact melanin production and can be divided into two main types: oculocutaneous albinism, which affects multiple areas, and ocular albinism, which is limited to the eyes. Clinical features include iris transillumination, foveal hypoplasia, abnormal crossing of the visual pathways, photophobia, and refractive errors. Management focuses on sun protection and early vision screening.

1. Albinism
characterized by absent or decreased tissue melanin

2. The disorder can be divided into two groups:
• oculocutaneous albinism (OCA)-—the most common condition
hypopigmentation disorders with varying degrees of involvement of
the eyes, hair, and skin
• the second group is the less common group called ocular albinism
(OA) with disease involvement limited to the eyes
• Oculocutaneous albinism is a group of autosomal recessive conditions
associated with mutations in several enzymes or membrane proteins
that contribute to melanin synthesis.
• classically been organized into two broad categories, tyrosinase-
positive (mild to moderate) and tyrosinas-negative (severe) albinism

3. OCA Type 1
This type, generally known
as tyrosinase-related OCA,
constitutes several subtypes
that occur due to mutation
in TYR gene for tyrosinase
(chromosome 11q14-q21).
Tyrosinase enzyme catalyzes
the first two steps in the
melanin biosynthesis
pathway, responsible for
converting tyrosine to DOPA
and subsequently to
DOPAquinone.
OCA Type 2
most common type of albinism
throughout the world with the
highest frequency in equatorial
Africa. The characteristic gene
involvement for OCA2 is
the OCA2 gene, previously
known as P gene. OCA2 is
responsible for melanosome
function as it helps regulate the
influx of tyrosine and other
internal environment of the
melanosome thus affecting the
functionality of the organelle
and melanin production.

4. OA Type 2
• Also known as Aland Island eye disease or
Forsius-Eriksson type ocular albinism, OA2 is
a rare X-linked disorder with similar clinical
manifestations as OA1 with the additional
protan color vision defect and defective dark
adaptation.
OA 1
Also known as Nettleship-Falls ocular albinism, this
disorder is inherited in an X-linked recessive manner
and thus occurs only in boys
Other potential findings are iris transillumination in
75%, hypopigmented macules of the skin, and
biopsy evidence of macromelanosomes in those
skin segments.OA1 has been associated with late-
onset sensorineural deafness (OASD

5. Clinical features
• Iris transillumination: The iris in albinism has little to no pigment to screen
out stray light coming into the eye. On slit lamp exam, the examiner may
detect speckled or diffuse transillumination defect.
• This finding, while common with albinism, is not specific as iris
transillumination occurs in diseases unrelated to albinism such
as pseudoexfoliation, pigment dispersion syndrome, megalocornea, iris
atrophy, and Axenfeld-Rieger spectrum.

6. • Foveal hypoplasia (absence of a foveal pit): In albinism, the retina does
not develop normally before birth and in infancy because of
inappropriate retinal pigment epithelium (RPE) pigmentation that is
required for macular development. Optical coherence tomography
(OCT) can demonstrate an absence of the foveal pit and the loss of
normal thinning of the retina. Also, the foveal avascular zone is small
or nonexistent with vessels crossing the area 2 disc diameter temporal
temporal to the optic disc margin.
• Foveal hypoplasia is the single most important contributor to poor
vision in albino patients.

8. • Abnormal decussation of the visual pathways: Normally about half of
optic nerve fibers from each eye decussates at the optic chiasm to the
contralateral side, contributing to stereopsis. Albinism is associated
with fiber over-decussation, resulting in crossing of up to 90% of fibers
fibers to the contralateral side and thus strabismus and loss of
stereopsis.

9. • Photophobia: Sensitivity to bright light and glare can occur due to
scattering of light within the eye. Patients may prefer to wear
sunglasses to reduce their sensitivity to light.
• Refractive Errors: Both myopia and hyperopia can occur, and
astigmatism is very common.

11. Differential dx
• Waardenburg Syndrome(WS)
WS is an autosomal dominant disorder notable for patchy areas of depigmentation of the hair and
skin in piebald-like distribution, heterochromia irides (pigment abnormality of the iris), and broad
nasal root.
Albinoidism
• Albinidoism is an autosomal dominant mutation with incomplete penetrance that results in
hypopigmentation. The affected patients have normal vision, retinal development, and no
nystagmus. This phenotype may represent the intermediate phenotype between wild type and
true albinism with macular hypoplasia

12. management
• Patients with albinism are at higher risk for squamous cell and basal
cell cancers in sun-exposed areas, and thus should be strongly
encouraged to limit their sun exposure through avoiding outdoor
occupations and through using sun-protective products such as
appropriate clothing, large-brim hats, sunglasses, and sunscreen
agents. An early eye examination is required to detect large refractive
errors and to facilitate early diagnosis and management of amblyopia