Albinism - Eye Notes

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Abnormalities in the synthesis of melanin resulting in pigment deficiency of

Clinical features

VA is reduced due to foveal hypoplasia (cp with albinoidism wherein the foveal architecture is normal) usually to 6/60
Increased decussation of temporal fibres at the chiasm: evident on VEP with increased contralateral hemisphere response to monocular stimulation (chiasmal misrouting)
Nystagmus: pendular and horizontal (lessens with age)
Photophobia
Strabismus
Ametropia (high errors of both types)
Iris hypopigmentation/transillumination
Fundus hypopigmentation with large choroidal vessels
Anterior segment dysgenesis (occasionally)

X-linked, affecting the OA1 gene
Female carriers show mild, patchy features
OCT: bulging photoreceptor/outer nuclear layers with abnormal persistence of the inner retinal layers at the fovea

Autosomal recessive: multiple subtypes with overlapping phenotypes
Increased risk of BCC and SCC
Systemic features: variable hypopigmentation of the skin and hair
Complete vs partial (aka tyrosinase-negative vs tyrosinase-positive)
- Tyrosinase positive: slow darkening of skin, hair, irides and RPE over time (associated with improved nystagmus and visual acuity)
- Tyrosinase negative (complete): no gain in pigment
Hermansky-Pudlak syndrome:
- Mild oculocutaneous albinism
- Low platelets (easy bruising)
- Pulmonary/renal/GI abnormalities (fibrosis and IBD)
- Cardiomyopathy
- Prevalent in Puerto Rican ancestry
Chediak-Higashi syndrome:
- Mild oculocutaneous albinism
- Leucocyte abnormalities: recurrent pyogenic infections
- Lymphoid malignancies
Waardenburg syndrome (autosomal dominant)
- Poliosis
- Synophyrs (monobrow)
- Deafness
- Lateral displacement of medial canthi
- Segmental iris hypochromia

Correct ametropia to prevent amblyopia and consider surgery for strabismus or nystagmus