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Ocular Implications in Albinism
Doctor Manuela Gherardini - Doctor Ignazio Zucca
Albinism represents a group of disorders linked to mutations in one or more genes involved in the melanin synthesis, which results in a reduction or absence of pigmentation in the skin, hair and eyes (oculocutaneous albinism) or just in the eyes (ocular albinism).
Hypopigmentation is accompanied by specific alterations of the visual system that result in reduced visual acuity, photophobia, strabismus and nystagmus.
A typical alteration involves the arrangement of the nerve fibers that make up the optic chiasma.
Part of the fibers from the optic nerve that should go on in the ipsilateral optic tract cross over themselves, leading to an increase in the cross-component.
This implies a different representation of the binocular map in areas such as the lateral geniculate body, an important optical station, that translates into impairment of the ocular motility and stereopsis.
The cause of this abnormal behaviour can be found in alterations of the retinal development controlled by the melanin.
The growth of the ganglion cells's axons, which will form the optic nerve, is slowed down, so these nervous structures are not present during the formation of the chiasma and are diverted to the opposite side.
There is still no treatment for ocular hypopigmentation. Experiments on gene therapy are particularly suitable due to where the eye sits (a secluded area easily accessible with non-invasive techniques as the ERG and the OCT.)
Some of the structural alterations caused by albinism can be repaired with gene therapy, which is a new treatment option that has already been tested successfully in other eye diseases.
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