ARTICLE 4: RETINITIS PIGMENTOSA Retinitis pigmentosa (RP) is a group of genetic conditions. In the progression of symptoms for RP, night blindness generally precedes tunnel vision by years or even decades. Many people with RP do not become legally blind until their 40s or 50s and retain some sight all their lives. Others go completely blind from RP, in some cases as early as childhood. Progression of RP is different in each case. RP is a type of progressive retinal dystrophy, a group of inherited disorders in which abnormalities of the photoreceptors (rods and cones) or the retinal pigment epithelium (RPE) of the retina lead to progressive visual loss. Affected individuals first experience defective dark adaptation or nyctalopia (night blindness), followed by reduction of the peripheral visual field (known as tunnel vision) and, sometimes, loss of central vision late in the course of the disease. Diagnosis The diagnosis of retinitis pigmentosa relies upon documentation of progressive loss in photoreceptor function by electroretinography (ERG) and visual field testing. The mode of inheritance of RP is determined by family history. At least 35 different genes or loci are known to cause "nonsyndromic RP" (RP that is not the result of another disease or part of a wider syndrome). Genetic counseling depends on an accurate diagnosis, determination of the mode of inheritance in each family, and results of molecular genetic testing. Associations Retinitis pigmentosa is seen in a variety of diseases, so the differential of this sign alone, is broad. RP combined with progressive deafness is called Usher syndrome. RP combined with opthalmoplegia, dysphagia, ataxia, and cardiac conduction defects is seen in the mitochondrial DNA disorder Kearns-Sayre Syndrome (aka Ragged Red Fiber Myopathy) RP combined with retardation, peripheral neuropathy, acanthotic (spiked) RBCs, ataxia, steatorrhea, is absence of VLDL is seen in abetalipoproteinemia. Other conditions include neurosyphilis, toxoplasmosis(Emedicine "Retinitis Pigmentosa"), abetalipoproteinemia, and Refsum's disease. Treatment A new treatment that has been shown to delay and potentially reverse blindness received CE Mark approval in the European Union. The first-of-its-kind therapy, developed by ScyFIX, uses microcurrent neuromodulation to help prevent vision loss and even restore sight for patients with low-vision blindness-related diseases. This is the first-ever device therapy approval for Retinitis Pigmentosa. ScyFIX clinical data was presented at the ISCEV (International Society of Clinicians in the Electrophysiology of Vision), the Retina Society, and the American Academy of Ophthalmology during 2008. Sixty-three (63%) of RP patients expanded their visual fields within six months of therapy. Patients also improved visual acuity to the point that they are now able to read newspapers and use mobile phones--this was not possible prior to receiving the therapy from ScyFIX's FDA trials which have been in progress for more than two years.
Genetics Retinitis pigmentosa (RP) is one of the most common forms of inherited retinal degeneration. This disorder is characterized by the progressive loss of photoreceptor cells and may eventually lead to blindness. There are multiple genes that, when mutated, can cause the Retinitis pigmentosa phenotype. In 1989, a mutation of the gene for rhodopsin, a pigment that plays an essential part in the visual transduction cascade enabling vision in low-light conditions, was identified. Since then, more than 100 mutations have been found in this gene, accounting for 15% of all types of retinal degeneration. Most of those mutations are missense mutations and inherited mostly in a dominant manner. Prevention The progression of the disease can be reduced by the daily intake of 15000 IU (equivalent to 4.5 mg) of vitamin A palmitate.[13] Recent studies have shown that proper vitamin A supplementation can postpone blindness by up to 10 years.[14] Scientists continue to investigate possible treatments. Future treatments may involve retinal transplants, artificial retinal implants,[15] gene therapy, stem cells, nutritional supplements, and/or drug therapies. New researches Scientists at the Osaka Bioscience Institute have identified a protein, named Pikachurin, which they believe could lead to a treatment for retinitis pigmentosa. In a study published in the journal Nature, researchers working with mice at the University College London Institutes of Ophthalmology and Child Health and Moorfields Eye Hospital, transplanted mouse stem cells which were at an advanced stage of development, and already programmed to develop into photoreceptors, into mice that had been genetically induced to mimic the human conditions of retinitis pigmentosa and age-related macular degeneration. These photoreceptors developed and made the necessary neural connections to the animal's retinal nerve cells, a key step in the restoration of sight. Previously it was believed that the mature retina has no regenerative ability. This research may in the future lead to using transplants in humans to relieve blindness. dr. jitender aggarwal ceo sarthak educational trust dg-2, 248-a vikas puri new delhi-18 www.disabilitymanagementcell.com To unsubscribe send a message to [email protected] with the subject unsubscribe. To change your subscription to digest mode or make any other changes, please visit the list home page at http://accessindia.org.in/mailman/listinfo/accessindia_accessindia.org.in
