physician research

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The Vogt–Koyanagi–Harada Syndrome (VKH) is a multi-system disorder characterized by severe uveitis and CNS abnormalities even in the absence of ocular trauma (Andreoli CM, Foster CS (2006) Vitiligo-like depigmentation is seen in as many as 63% of VKH patients (Moorthy RS, Inomata H, Rao NA (1995)

OCULAR PIGMENTATION

Loss of ocular pigmentation can occur in the eyes of patients with vitiligo.The presence of the RPE and the melanin synthesized by both the RPE and melanocytes of the uveal tract are important for the guidance of the neural projections from the retina to the visual cortex of the brain. (Creel D, O’Donnell FE, Witkop CJ (1978). Neurons from the temporal half of each eye is directed to the ipsilateral visual cortex in the brain, whereas the neurons from the nasal half of each eye cross at the optic chiasma to the contralateral visual cortex of the brain. (Guillery RW (1974). In the absence of melanin synthesis, as characterized by albinism, this neuronal pattern is offset so that there is an increase in neurons crossing at the optic chiasma to the contralateral geniculate, resulting in the scrambling of the neuronal input to the visual cortex.

Minimal ocular inflammation has been reported in 5% of vitiligo patients and conversely idiopathic uveitis has been observed in 5% of patients with Vitiligo or poliosis (Wagoner MD, Albert DM, Lerner AB et al (1983)

OTIC PIGMENTATION

Otic melanocytes synthesise pigmented melanosomes until congested, and then halt melanin synthesis (Cable J, Steel KP (1991)

There are a few functions that are attributed to melanocytes of the ear that include the maintenance of endocochlear potential, and the prevention of noise- and/or toxin induced hearing loss. The endocochlear potential is known to regulate transduction of sound waves to the hair-cell receptors can be reduced in albinos (Conlee JW, Bennett ML (1993). Susceptibility to noise-induced hearing loss has been demonstrated in some animals and humans with albinism (Conlee JW, Abdul-Baqi KJ, McCandless GA et al (1988)

The evidence of an involvement of non-cutaneous melanocytes in common forms of vitiligo is limited therefore, there is currently no pressing need to assess the patients for hearing loss or specific visual deficiency.