Arrested development: High-resolution imaging of foveal morphology in albinism

John T Mcallister,Adam M Dubis,Diane M Tait,Shawn Ostler,Jungtae Rha,Kimberly E Stepien,C Gail Summers,Joseph Carroll

doi:10.1016/j.visres.2010.02.003

John T Mcallister, Adam M Dubis + Show 6 more

Open Access

https://doi.org/10.1016/j.visres.2010.02.003

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Journal: Vision research	Publication Date: Feb 10, 2010
Citations: 123	License type: publisher-specific-oa

Affiliation: Medical College of Wisconsin, University of Minnesota

Abstract

Albinism, an inherited disorder of melanin biosynthesis, disrupts normal retinal development, with foveal hypoplasia as one of the more commonly associated ocular phenotypes. However the cellular integrity of the fovea in albinism is not well understood – there likely exist important anatomical differences that underlie phenotypic variability within the disease and that also may affect responsiveness to therapeutic intervention. Here, using spectral-domain optical coherence tomography (SD-OCT) and adaptive optics (AO) retinal imaging, we obtained high-resolution images of the foveal region in six individuals with albinism. We provide a quantitative analysis of cone density and outer segment elongation demonstrating that foveal cone specialization is variable in albinism. In addition, our data reveal a continuum of foveal pit morphology, roughly aligning with schematics of normal foveal development based on post-mortem analyses. Different albinism subtypes, genetic mutations, and constitutional pigment background likely play a role in determining the degree of foveal maturation.

Highlights

Albinism is an inherited disorder of melanin biosynthesis, associated with absent or reduced melanin pigment in the eye, and often in the skin and hair
We observed varying degrees of foveal maturity and cone specialization in the albinotic retina, which roughly align with schematics of normal foveal development based on post-mortem analyses (Isenberg, 1986; Mann, 1950; Provis, Diaz, & Dreher, 1998; Springer, 1999)
Our anatomic data obtained with adaptive optics (AO) and SD-Optical coherence tomography (OCT) reflect the lack of consensus regarding the albinotic fovea in the literature

Summary

Introduction

Albinism is an inherited disorder of melanin biosynthesis, associated with absent or reduced melanin pigment in the eye, and often in the skin and hair. Oculocutaneous albinism type 1 (OCA1; MIM 203100) is a recessive disorder in which individuals have a mutation in the tyrosinase gene on chromosome 11q14.3. Those who never develop any melanin pigment within the eye, hair, and skin have OCA1A, while those with development of some melanin pigment due to a ‘‘leaky” mutation that allows residual enzyme activity have OCA1B (King et al, 2003). Significant work remains in elucidating the relationship between foveal maldevelopment and visual function in albinism (Jeffery, 1997). This lack of clarity stems in part from ambiguity surrounding foveal anatomy in albinism, with regard to foveal cone specialization

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