Pigmentary Retinite

The pigmentary retinites are a whole of genetic diseases of the eye. The name of retinitis pigmentosa would have been proposed in 1855 by the Dutch Franz Donders .

This unit is genetically heterogeneous implying the photoreceivers (cones and Bâtonnet) and the pigmentary epithelium. They appear initially by a loss of the Night vision followed by a contracting of the Field of vision. The loss of the central Vision is late. It is caused by a genetic mutation in the cells of the retina: sticks. When the cones, other cells of the retina, follow the same evolution, it is blindness.

Pigmentary retinite can be divided into nonsyndromic, syndromic or systemic retinite pigmentary reaching other bodies. This article treats only nonsyndromic pigmentary retinites.

Incidence & prevalence

1 person reached out of 5000, is approximately 40000 French. It is the most frequent cause of blindness at the intermediate person of age in the developed countries.

Description

In 30% of the cases, retinite is associated with lesions of other bodies forming about thirty syndromes. Most frequent is the Syndrome of Usher associating a deafness. The Syndrome of Bardet-Biedl and the Maladie of Refsum are rarer syndromes.

Diagnosis

The ocular attack occurs at variable ages but begin generally early with a reduction from the night vision (preferential lesions of the Bâtonnet S, cells of the bottom of eye more adapted to the half-light). In the second time, the Field of vision narrows being able to lead to a vision “in tunnel”. The central vision is reached around 60 years.

The diagnosis is thus done primarily by the analysis of the Field of vision finding Scotome S peripherals (“holes” in the noncentral field of view). According to the syndrome, can be there associated an eye trouble with the colors, a disorder of the refraction.

The Ophtalmoscope can detect a Cataracte, typically under-capsulaire, in half of the cases. The Fund of eye watch a hyperpigmentation of the periphery of the Retina, witness of cellular death.

The electroretinogram would allow a detection of the disease before the latter appears.

Differential diagnosis

Various types

One distinguishes according to their mode of transmission various types of pigmentary retinite. Nearly 45 types different of genetic attack were described, the majority of genes coding of photosensitive proteins of the sticks.

Treatment & assumption of responsibility

Genetic disease, it is until today incurable. Encouraging tests were carried out in 1998 by the team of Pr José-Alain the Sahel of the university of Strasbourg. In the mouse, sticks of healthy individuals were insulated and transplanted at individuals reached of the pigmentary retinite shape. The grafted sticks secrete a substance which protects the cone S from the destruction. This technique should be applicable to the man.

A supplementation in Vitamine has could slow down the evolution of the disease. In the same way, a mode enriched in Omega-3 would delay the appearance of blindness.

Certain syndromes (rare) also have an effective specific treatment: a mode low in Acid phytanic, can stop the evolution of the Maladie of Refsum.

The genetic Council

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