Retinitis Pigmentosa

  • Primary pigmentary retinal dystrophy predominantly affects rods more than cones
  • Sporadic >Autosomal recessive > Autosomal dominant > X-linked recessive
  • Night blindness or nyctalopia is the characteristic feature — due to degeneration of rods
  • Tubular vision in advanced cases
  • Retinal pigmentary changes resembling bone corpuscles — typically perivascular
  • Optic disc becomes pale and waxy — consecutive optic atrophy
  • Annular or ring shaped scotoma is the typical visual field defect
  • Later only central vision is left (tubular vision)
  • ERG is subnormal or abolished (scotopic affected before photopic; b wave affected before a wave)
  • EOG - absence of light peak
  • Refsum's syndrome: peripheral neuropathy, cerebellar ataxia
  • Usher's syndrome: labyrinthine deafness
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