Retinitis Pigmentosa

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  • RETINITIS PIGMENTOSA
    • primary pigmentary retinal dystrophy
    • hereditary disorder predominantly affecting the rods more than the cones.
    • Inheritance
      • Most common mode is autosomal recessive .(MCQ)
      • Second common ,autosomal dominant
      • X-linked recessive is the least common.
    • It appears in the childhood and progresses slowly
    • often result in blindness in advanced middle age.
    • Males are more commonly affected than females in a ratio of 3:2.
    • Disease is almost invariably bilateral and both the eyes are equally affected.
    • Clinical features
      • Visual symptoms
        • Night blindness .(MCQ)
          • It is the characteristic feature
          • present several years before the visible changes in the retina appear.
          • It occurs due to degeneration of the rods.
        • Dark adaptation.
          • Light threshold of the peripheral retina is increased
          • the process of dark adaptation itself is not affected until very late.
        • Tubular vision occurs in advanced cases.(MCQ)
    • Fundus changes(A Frequently asked MCQ in MD Entrance )
      • Retinal pigmentary changes.
        • These are typically perivascular
        • resemble bone corpuscles in shape.
        • Initially, these changes are found in the equatorial region only and later spread both anteriorly and posteriorly.
      • Retinal arterioles are attenuated (narrowed) and may become thread-like in late stages.
      • Optic disc
        • becomes pale and waxy in later stages
        • ultimately consecutive optic atrophy occurs
      • Other associated changes
        • colloid bodies
        • choroidal sclerosis
        • cystoid macular oedema
        • atrophic or cellophane maculopathy (MCQ)
    • Visual field changes
      • Annular or ring-shaped scotoma
        • a typical feature
        • corresponds to the degenerated equatorial zone of retina.
      • As the disease progresses, scotoma increases anteriorly and posteriorly and ultimately only central vision is left (tubular vision).
      • Eventually even this is also lost and the patient becomes blind.
    • Electrophysiological changes
      • Typical electrophysiological changes appear early in the disease before the subjective symptoms or the objective signs (fundus changes) appear.
        • Electro-retinogram (ERG) is subnormal or abolished.
        • Electro-oculogram (EOG) shows absence of light peak.
    • Associations of retinitis pigmentosa
      • Ocular associations include
        • myopia, primary open angle glaucoma
        • microphthalmos, conical cornea
        • posterior subcapsular cataract.
      • Systemic associations.
        • Laurence-Moon-Biedl syndrome is characterised by
          • retinitis pigmentosa
          • obesity
          • hypogenitalism,
          • polydactyly
          • mental deficiency.
        • Cockayne’s syndrome  comprises
          • retinitis pigmentosa
          • progressive infantile deafness
          • dwarfism
          • mental retardation
          • nystagmus and ataxia.
        • Refsum’ssyndrome is characterized by
          • retinitis pigmentosa
          • peripheral neuropathy
          • cerebellar ataxia.
        • Usher’ssyndrome includes
          • retinitispigmentosa
          • labyrinthine deafness.
        • Hallgren’ s syndrome comprises
          • retinitis pigmentosa, vestibulo-cerebellar ataxia
          • congenital deafness and mental deficiency.

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