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Nw2016 retinitis pigmentosa

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retinitis pigmentosa, macular edema, cataract, diamox, acetazolamide, argusII, retinal prosthesis, bionic eyes, retinal implant,

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Nw2016 retinitis pigmentosa

  1. 1. Retinitis Pigmentosa : A Brief Nawat Watanachai August 2016
  2. 2. Retinitis Pigmentosa • Retinitis pigmentosa (RP) is • a group of genetic disorders that affect the retina’s ability to respond to light • slow loss of vision • begin with nyctalopia • loss of peripheral vision • blindness • +/- photopsia
  3. 3. characteristics • hereditary • rate of progression and degree of visual loss varies from person to person • Most RP are legally blind by age 40 • central visual field of less than 20 degrees • XR • males : more often and more severe • females : carry the genes and experience vision loss less frequently.
  4. 4. Eye Tests • visual field testing • Most useful for follow-up care • Goldmann (kinetic) perimetry is recommended • Color testing • Commonly, mild blue-yellow axis color defects • Dark adaptation study • Disproportionately reduced contrast sensitivity relative to VA • Genetic subtyping
  5. 5. Eye Tests • optical coherence tomography (OCT) • not useful in diagnosing RP • may help in CME
  6. 6. Eye Tests • Fluorescein angiography (FA, FFA) • rarely useful in diagnosing RP • may help in CME
  7. 7. Eye Tests • Electroretinogram (ERG) • Most critical diagnostic test for RP • Electro-oculogram (EOG) • Not helpful in diagnosing RP • but can identify Best vitelliform macular dystrophy • central macular changes • normal ERG, and abnormal EOG
  8. 8. Systemic diseases that related to RP • hearing loss and RP • Usher syndrome • Waardenburg syndrome • Alport syndrome • Refsum disease • Kearns-Sayre syndrome • External ophthalmoplegia, lid ptosis, heart block, and pigmentary retinopathy • Abetalipoproteinemia • Fat malabsorption, fat-soluble vitamin deficiencies, spinocerebellar degeneration, and pigmentary retinal degeneration • Mucopolysaccharidoses • Hurler syndrome, Scheie syndrome, Sanfilippo syndrome • Bardet-Biedl syndrome • Polydactyly, truncal obesity, kidney dysfunction, short stature, and pigmentary retinopathy • Neuronal ceroid lipofuscinosis • Dementia, seizures, and pigmentary retinopathy • infantile form is known as Jansky-Bielschowsky disease • juvenile form is Vogt-Spielmeyer-Batten disease • adult form is Kufs syndrome
  9. 9. management : medical • Acetazolamide • Macular edema (Fishman et al and Cox et al) • oral acetazolamide helps • Topical acetazolamide less helps • Adverse effects: • fatigue, renal stones • loss of appetite, hand tingling • electrolyte imbalance, anemia • steroid for macular edema • may be useful but has not been well studied
  10. 10. management : medical • Pharmacotherapy? • Fat-soluble vitamins • vitamin A, C, E • Ca-channel blockers • iltiazem • Carbonic anhydrase inhibitors • acetazolamide, methazolamide • Docosahexaenoic acid (DHA) • Lutein, Zeaxanthin • medications with potential adverse effects in RP: • Isotretinoin (Accutane) • Sildenafil (Viagra) • High-dose vitamin E
  11. 11. management : surgical • cataract • cataract extraction • Retina • retinal implant • gene therapy • stem cell therapy • others : RPE transplantation, surgical growth factors placement
  12. 12. retinal prosthesis • ARGUS II prosthesis : U of southern california • Alpha IMS • Microsystem-based visual prosthesis (MIVP) • spiral cuff electrode around the optic nerve • implantable miniature telescope • Harvard/MIT retinal implant • artificial silicon retina (ASR) • Photovoltaic retinal prosthesis • Bionic vision australia • dobelle eye • intracortical visual prosthesis
  13. 13. retinal prosthesis • ARGUS II prosthesis : • U of southern california • 60 electrodes • approved • EU 2011 • US 2013
  14. 14. retinal prosthesis • Alpha IMS • Tubingen, GER • subretinal prosthesis • collect incident light • transform to electrical signals • stimulate ganglion cells • 1500 electrodes
  15. 15. retinal prosthesis • Alpha IMS
  16. 16. gene therapy • under investigation • to replace the defective protein by using DNA vector (eg, adenovirus, lentivirus) • Gene therapy was successful in providing the missing protein to a dog with Leger congenital amaurosis (LCA) • adeno-associated virus (AAV) • Briard dog with RPE65 mutations after treatment had 20% of its RPE cells express the functional protein, thereby allowing the dog to see • also effective in a mouse model of Leber congenital amaurosis • Trials have also begun for RP, although currently only for MERTK gene mutation • problems : wide heterogeneity of defects in RP • Jacobson et al found that gene therapy is acceptably safe and effective in the extrafoveal retina for LCA caused by RPE65 mutations; however, no benefit and some risk was noted in treating the fovea. Age-dependent effects were not evident.[18] • It is not known which, if any, of the RP forms will show reversibility (even with a nondestructive reinsertion of the appropriate gene in the appropriate locus with appropriate regulation).
  17. 17. stem cells • Cell transplantation to treat retinal disease (including cells derived from stem cells) • to replace damaged RPE or photoreceptor cells • adult bone marrow–derived stem cells and embryonic stem cells • 2011, Advanced Cell Technology (ACT) • human trial of a stem-cell–derived therapy • for ARMD, Stargardt disease • stem cells were differentiated into cells with an RPE phenotype • PPV • injected under the retina • Initial results demonstrated safety and a trend toward visual improvement in 18 patients over 3-12 months • RPE cell transplants (not derived from stem cells) • placed into the subretinal space to rescue photoreceptors in animal models of RP

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