Ocular Albinism (OA) Clinical Trial
Official title:
A Randomized Placebo-controlled Trial to Investigate the Effect of Lutein and Zeaxanthin Supplementation on Macular Pigment and Visual Function in Albinism - LUtein for VIsion in Albinism (LUVIA)
The LUVIA study is a randomized placebo-controlled trial designed to investigate the effects of lutein and zeaxanthin supplementation on macular pigment and visual function in ocular or oculocutaneous albinism. Lutein and zeaxanthin supplementation will be compared to a placebo (no treatment) gel pill over the period of 12 months, with study visits approximately every 3 months for the first year and a final visit 18 months after enrollment.
Ocular and oculocutaneous albinism represent a spectrum of disorders with absent or
significantly diminished amount of melanin either across different body tissues - skin, hair,
eye (Oculocutaneous Albinism 1 and 2), or exclusively in eye tissues only (Ocular Albinism 1)
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The functionality and the clinical findings are diverse (the phenotype), and no direct
correlation has been established to the underlying mutations (genotype).
The common ocular phenotype includes iris transillumination, foveal hypoplasia, nystagmus,
reduced visual acuity, refractive error, photosensitivity and abnormal development of the
visual pathways with characteristic abnormal routing of ganglion cell axons in the chiasma,
resulting in abnormal visually evoked potentials. Current treatment options are limited to
optical methods and low vision aids.
The mechanism of melanin pigment formation in the RPE cells and its role in the visual
pathways and structures development is not completely understood, but a correlation was found
between the amount of fundus pigmentation and visual function in albino patients. The absent
pigmentation within the retinal pigment epithelium (RPE) may thus contribute to visual
performance deficits.
The macular pigment (MP) consists of two main carotenoids, lutein and zeaxanthin, which are
concentrated in the macular region of the retina. MP is hypothesized to function via a
protective mechanism by absorbing blue light incident on the retina thereby reducing
oxidative damage to the underlying photoreceptors. It is also thought to improve visual
function via reduction of chromatic aberration and glare. It is currently unclear as to how
the variability in macular pigment optical density (MPOD) affects congenital retinal
conditions. The MP would, however, be a hypothetical and good candidate to improve visual
performance - simply by increasing pigmentation, reducing light scatter and thus glare
sensitivity.
As this pigment is not produced in the retina, but is absorbed via diet, it can be
manipulated by alteration in diet and supplementation thereby providing potential therapy for
retinal diseases. It is however necessary first to see if MPOD levels are measurable in this
disorder before dietary advice can be provided after completion of the LUVIA study. Further
to this, evaluation of both the structural and functional properties of the retina will
provide greater insight into the possible function of MP in this retinal disease including
whether supplementation would be of benefit.
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