Retinitis Pigmentosa

History

• Gradual visual loss
  • Have you noticed that your vision is becoming poorer?
  • Have you noticed yourself bumping into things more often than usual?
  • How long has this been going on for?
  • Do you find it difficult to see things at night?
  • Do colours appear less vibrant than usual?
• Family history
  • Has anyone in your family had eye problems?
  • Is anyone in your family blind?
• Systemic disorders
  • How is your hearing?
  • Do you find it difficult to reach for objects on shelves?
  • Do you have any problems climbing stairs?
  • Do you have trouble getting up from a standing position?
  • Have you ever fainted suddenly?
  • Have you ever felt your heart beating uncontrollably?
  • Do you feel unsteady on your feet?
  • Have you noticed any blood or bubbles in your urine?

Examination

• General inspection
  • Visual aids
  • Support group card
  • Polydactyly
  • Hearing aids
• Eyes
  • Pupils usually equal and reactive to light
  • Visual acuity
    • May be severely affected in late stages
    • In early stages, may have peripheral retinopathy only with relative macula sparing
  • Visual fields reduced in early stages of disease
  • Fundoscopy
    • Peripheral bone spicule pigmentation with relative macula sparing
    • Waxy pallor of the optic disc
    • Attenuation of retinal blood vessels
• Proximal myopathy
• Ataxia
• Implantable cardiac device (permanent pacemaker / implantable cardiac defibrillator)

Differential diagnosis

• Primary (non-syndromic) retinitis pigmentosa: autosomal dominant (30%), autosomal recessive (20%), X-linked (15%)
• Ciliopathies (primary cilium dysfunction)
  • Bardet-Biedl syndrome: RP, polydactyly, renal disease, hypogonadism, neurological disease, obesity, learning disability
  • Alström syndrome: RP, sensorineural hearing loss, renal disease, hypogonadism, neurological
• Lysosomal disorders: RP, hepatosplenomegaly, neurological disorders, pulmonary infiltrates, hearing loss
• Mitochondrial disorders
  • Kearns-Sayre syndrome: RP, chronic progressive external ophthalmoplegia, cardiac conduction defects, ataxia
  • Neuropathy, ataxia, retinitis pigmentosa (NARP): proximal myopathy, ataxia, seizures, sensory neuropathy, dementia and retinitis pigmentosa
• Friedrich’s ataxia: ataxia, distal muscle wasting, optic atrophy and / or RP; autosomal recessive

Investigations

• Confirm diagnosis: full-field electroretinography (ERG) – measures electrical response of retina to light
  • In retinitis pigmentosa: reduction in amplitude and delay in timing of electrical signal
• Look for complications of syndromic disorders:
  • Electrocardiogram (heart block in Kearns-Sayre)
  • Renal function tests (ESRD with ciliopathies)
  • Audiometry to look for sensorineural hearing loss
  • EMG if proximal myopathy detected on clinical examination

Management

• Multidisciplinary team approach
• Patient education on progressive nature of disease
  • Should stop driving
• Referral for job counselling
• Referral to occupational therapy for visual aids
• Referral to ophthalmology for formal visual assessment
• Referral to ENT for screening for sensorineural hearing loss
• Referral for genetic counselling

Summary

Sir, this patient has retinitis pigmentosa. He presents with an insidious history of visual loss, beginning with problems with night vision and apparent visual field defects. On examination of the fundus, there are bone spicule pigments on the retina, and the optic disc is pale. There is no evidence of hearing loss, polydactyly, ophthalmoplegia or myopathy to suggest a syndromic retinitis pigmentosa. He requires genetic counseling and referral to ophthalmology for more definitive investigation.