Oculocutaneous Albinism: An Overview

Ruqaiyah Behranwala

Key Learning Points

  • OCA encompasses a spectrum of disease which are genetically and phenotypically diverse
  • Characteristic ocular manifestations of OCA often arise within the first 3-6 months of life
  • High index signs and symptoms include foveal hypoplasia, chiasmal misrouting on electrophysiology, iris transillumination and nystagmus
  • Currently there are no curative treatments for OCA however management focuses on refractive correction, contrast enhancement, photophobia control and multi-disciplinary support
  • Early diagnosis is vital for low vision intervention, amblyopia treatment and appropriate genetic counselling which can significantly improve functional vision and quality of life
  • Genetic testing clarifies diagnosis and supports holistic care

Albinism encompasses a group of heterogenous genetic conditions affecting the melanin synthesis pathway leading to a reduction or absence in melanin production. In ophthalmology, albinism can be broadly categorised into two groups: oculocutaneous albinism (OCA) and ocular albinism (OA). In OCA, hypopigmentation involves the skin, hair, and eyes, whereas in OA pigmentary changes are limited to ocular structures, primarily the iris and retina (1). Both OA and OCA are rare disorders that share similar characteristic ocular findings and visual challenges. This article focuses on oculocutaneous albinism.

Overview of OCA: Prevalence, Inheritance and Subtypes

The prevalence of OCA varies by type and country. It is estimated that it affects 1 in 4,000 to 7,000 people in African populations and 1 in 12,000 to 15,000 people in European populations (2). It is inherited in an autosomal recessive pattern which means both copies of the gene in each cell must have a variant to cause the disorder. In most cases there is no previous family history of albinism (3).

Currently there are 8 known forms of OCA with varying levels of clinical severity and presentation. A key enzyme in melanin biosynthesis is tyrosinase and patients with OCA can be broadly divided into tyrosinase-producing (tyrosinase-positive e.g. OCA1B, OCA2, OCA3, OCA4) and tyrosinase non-producing (tyrosinase-negative e.g. OCA1A) groups. Tyrosinase-negative groups give rise to more severe disease. Tyrosinase positive indicates the presence of some functional enzyme, resulting in accumulation of pigment overtime which can slightly improve visual acuity (1,3).

Diagnosis

The diagnosis of OCA is based on a combination of characteristic clinical signs and symptoms, supportive investigations such as OCT and electrophysiology, and genetic testing.

Early symptoms in childhood include poor visual acuity, nystagmus, photophobia and double vision due to strabismus (3). Clinical signs on slit lamp examination include iris transillumination, cataracts and fundus hypopigmentation. OCT demonstrates foveal hypoplasia and electrophysiology shows a pattern of over decussation of optic nerve fibres at the chiasm (4,5).

For patients suspected of having OCA, a panel of 38 genes known to contribute to the condition can be analysed through the UK National Health Service (NHS) however currently whole-genome sequencing is not funded. Although different types of OCA are caused by mutations in different genes, the clinical phenotypes are not always distinguishable, making molecular diagnosis a useful tool and essential for genetic counselling.

Management: Visual rehabilitation and Multi-disciplinary Support

Initial management for OCA is visual rehabilitation. Visual acuity can be optomised with correction of refractive errors with spectacles or contact lenses. Early correction of large refractive errors and careful re-evaluation of refractive error changes overtime maximises visual outcome leading to reduced emmetropic amblyopia, improved binocularity and nystagmus (6).

Amblyopia is classically treated with patching treatment however this can increase nystagmus (7). In OCA, pharmacological therapies to treat nystagmus include gabapentin, memantine and topical brinzolamide. Surgical options include the Kestenbaum procedure and four muscle tenotomy and reattachment surgery. Photophobia can be managed with sunglasses, photochromic lenses, tinted contact lenses and hats with a brim when outdoors (6,7).

In low vision assessment (LVA) clinics, individuals are assessed according to their specific visual tasks and needs, and an individualised low vision support plan is developed. In educational settings, appropriate accommodations such as high-contrast materials, large-print text, optical aids, and assistive technology help maximise visual function and support eligibility for special education services related to visual impairment (7).

Innovations

Adenovirus vector-based gene therapy is a promising approach to treating retinal disease by delivering therapeutic genes directly to affected cells. Currently, the only ocular gene therapy approved by the FDA and NICE is Luxturna targeting mutations in the RPE65 gene. RPE targeted gene therapy has been trialed in mouse and rat models for OCA type 1 and has shown that subretinal and suprachoroidal injections increases tyrosinase activity (8). However, these are preliminary studies with no known clinical trials yet.

References

  1. Forrester JV, Dick AD, McMenamin PG, Roberts F, Pearlman E. The eye: basic sciences in practice. 4th ed. London: Elsevier; 2016. p. 155.
  2. Kromberg JG, Flynn KA, Kerr RA. Determining a Worldwide Prevalence of Oculocutaneous Albinism: A Systematic Review. Invest Ophthalmol Vis Sci [Internet]. 2023 Jul 3;64(10):14. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC10353740/
  3. Kim JM, Adamopoulou C, Kim LA, Tripathy K, Bhagat N, Pathak AK, Lim JI, Elshatory YM; edited by Kim LA. Albinism. EyeWiki [Internet]. American Academy of Ophthalmology; 2025 Sep 18 [cited 2025 Dec 19]. Available from: https://eyewiki.org/Albinism
  4. Holder GE. Electrophysiology in the diagnosis of albinism. Eye (Lond). 2014;28(3):250–256. doi:10.1038/eye.2014.3. Available from: https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1755-3768.2014.2664.x
  5. Thomas MG, Kumar A, Mohammad S, Proudlock FA, Engle EC, Andrews C, Chan W‑M, Thomas S, Gottlob I. Structural grading of foveal hypoplasia using spectral‑domain optical coherence tomography: a predictor of visual acuity? Ophthalmology. 2011;118(8):1653–1660. doi:10.1016/j.ophtha.2011.01.028.
  6. Summers CG. Albinism: classification, clinical characteristics, and recent findings. Optom Vis Sci. 2009;86(6):659–662. doi:10.1097/OPX.0b013e3181a5254c
  7. Thomas MG, Zippin J, Brooks BP. Oculocutaneous albinism and ocular albinism overview. In: Adam MP, Bick S, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025 Apr 13 [cited 2025 Dec 19]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK590568/
  8. Song L, Ren C, Luo M, Wang Q, Liu F, Hu M, et al. Retinal pigment epithelium-targeting gene therapy corrects ocular symptoms in mouse and rat models of oculocutaneous albinism type I. MedComm [Internet]. 2025 Oct 20;6(11):e70433. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC12536886/

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