Retinitis Pigmentosa

RETINITIS PIGMENTOSA
  • Primary pigmentary retinal dystrophy predominantly affects rods more than cones
  • Sporadic >Autosomal recessive > Autosomal dominant > X-linked recessive
  • X-linked cases are most severe
  • Incidence 5 per 1000 people
  • Males more affected
  • Invariably bilateral
Signs and Symptoms
  • Night blindness or nyctalopia is the characteristic feature — due to degeneration of rods
  • Light threshold of peripheral retina is increased. Dark adaptation is not affected until very late
  • Tubular vision in advanced cases
  • Retinal pigmentary changes resembling bone corpuscles — typically perivascular
  • Attenuation (narrowing) of retinal arterioles
  • 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
Syndromes associated with Retinitis pigmentosa
  • Refsum's syndrome: peripheral neuropathy, cerebellar ataxia
  • Usher's syndrome: labyrinthine deafness
  • Laurence-Moon-Biedl: syndromeobesity, hypogenitalism, polydactyly, mental deficiency
  • Cockayne's syndrome: progressive infantile deafness, dwarfism, mental retardation, nystagmus, ataxia
  • Hallgren's syndrome: vestibulo-cerebellar ataxia, congenital deafness, mental deficiency
  • Friedrich's ataxia, Kearns-Sayre syndrome
Atypical forms of retinitis pigmentosa
  • Retinitis pigmentosa sine pigmento: all features of RP except visible pigmentary changes in the fundus
  • Sectorial RP: involvement of one sector of retina
  • Pericentric RP: pigmentary changes are confined to an area immediately around macula
  • Retinitis punctata albescens: innumerable discrete white dots scattered over the fundus without pigmentary changes
Exam Question
  • 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

Don't Forget to Solve all the previous Year Question asked on Retinitis Pigmentosa