Retinitis pigmentosa


Retinitis pigmentosa

Description, Causes and Risk Factors:

ICD-10: H35.5

Alternative Name: Pigmentary retinopathy.

Abbreviation: RP.

The retina is the layer of light-sensing cells lining the back of your eye that converts light rays into impulses. The impulses are sent through the optic nerve to your brain, where they are recognized as images.

Retinitis pigmentosa is a generic term for a group of disorders characterized by hereditary diffuse usually bilaterally symmetrical progressive dysfunction, cell loss and eventual atrophy of retina. Initially photoreceptors are involved and subsequently inner retina is damaged. Although both rods and cones are involved, damage to the rods is predominant. Retinitis pigmentosa may be seen in isolation or in association with systemic diseases.

The reported prevalence of typical retinitis pigmentosa is approximately 1: 50000 worldwide. Most commonly 46% of the cases are sporadic (recurring in scattered and irregular or unpredictable instances) with only one affected member in a given family.

In retinitis pigmentosa, the light receptor cells in the retina die off. The rod photoreceptors (which provide black and white vision) are mostly affected but sometimes the genetic disorder affects the cones or color vision photoreceptors. As the retina slowly degenerates and gradually loses its ability to transmit images to the brain, so there is a progressive loss of vision. Cells from the pigmented layer of the retina migrate into the layer containing nerve cells, causing the typical pattern of black or brown star shapes in the retina that gives the diseases their name.

Retinitis pigmentosa is thought to be caused by defects of certain genes in the body. The defects cause cells in the retina to malfunction and begin to break down. More than 100 different gene mutations that may lead to retinitis pigmentosa have been described.

Of those who inherit the disease, the milder forms are usually autosomal dominant, meaning that if you have the disease you have a 50 per cent chance of passing it on to your children. However, nearly half of those with RP have no family history at all.

Retinitis pigmentosa is often hereditary (runs in families). If you or your partner has retinitis pigmentosa, there may be up to a 50% chance that you will pass it along to your children.

RESEARCH ABSTRACT: The AD29 mutation in HPRP31 belongs to a series of mutations that were initially linked with the autosomal dominant disorder retinitis pigmentosa type 11. The HPRP31 gene encodes the hPrp31 protein that specifically associates with spliceosomal small nuclear ribonucleoprotein particles (snRNPs). Despite intensive research, it is still unclear how the AD29 (Ala216Pro) mutation causes retinitis pigmentosa.

Symptoms:

Retinitis pigmentosa causes slow loss of vision. Symptomsbegin with decreased night vision and later progressto loss of peripheral (side) vision. Some people mayalso have difficulty identifying colors. The rate of visionchange varies in different people depending on thegenetic makeup of their disorder.

Diagnosis:

Because of the huge number of faulty genes that can cause retinitis pigmentosa, many of which are not yet fully identified, screening is not straightforward. However, antenatal diagnosis is possible in some cases where there is a risk of X-linked and autosomal dominant retinitis pigmentosa.

Tests to evaluate the retina may include:

    Color vision.

  • Examination of the retina by ophthalmoscopy after the pupils have been dilated.

  • Fluorescein angiography.

  • Intraocular pressure.

  • Measurement of the electrical activity in the retina (electroretinogram).

  • Pupil reflex response.

  • Refraction test.

  • Retinal photography.

  • Side vision test (visual field test).

  • Slit lamp examination.

  • Visual acuity.

Treatment:

There is no cure for retinitis pigmentosa and there are, at the moment, no treatments that have been proven to stop the visual degeneration (although a number of treatments are under study including gene therapy). There has been some interest in using anti-oxidant compounds such as certain vitamins but there is no clear evidence that they help and there may even be a risk of harm.

However, in many cases the progression of the disease is slow and good support and visual aids can help people cope with the condition.

Although doctors recommend ascorbic acid but there is no evidence to prove that this medicine is helpful in treating this eye disease. Some doctors recommend bilberry as an alternative medicine but no study documents its safety in treating the patients suffering from retinitis pigmentosa.

Research has shown that vitamin A can slow the progression of retinitis pigmentosa. Your ophthalmologist can advise you about the risks and benefits of vitamin A and how much you can take safely.

Several clinical trials are in progress to investigate new treatments for retinitis pigmentosa.

Microchip implants that go inside the retina are in the early stages of development for treating blindness associated with this condition.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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