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Types of Visual Impairment

Types of Visual Impairment

 
 
 
Oculocutaneous                             
Albinism
 
  •  the eyes, skin and hair are affected by lack of pigmentation 
 
 
Ocular Albinism                       

 
             
 
  • lack of pigmentation limited to the eyes 
 
 
Cataracts              
 
  • opacities in the lens of the eye which scatter light onto the retina and lead to a reduction in clarity of sight 
  • can be present from birth or occur through trauma or the onset of old age
  •  associated with other eye conditions
  • full visual field but acuity varies widely 
  • can experience double vision when looking at bright objects against a dark background 
  • glare and dazzling lights will cause difficulties 
  • many people need optical aids for near and distance vision 
  • additional lighting can prove helpful 
 
 
Diabetic Retinopathy (as a result of Diabetes)
 
 

 

  • major cause of adult blindness 
  • presence of floaters caused by haemorrhages and debris 
  • fluctuating visual acuity 
  • distortion of vision 
  • visual field may be impaired depending on location of retinal disease 
  • diabetic condition affected by stress
  • sight loss creates additional problems such as poor circulation, consequently less tactile sensation, slower reflexes 
    and an increased sense of tiredness

 

 
Glaucoma
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Side effects of medication can include:
 
 
 
 
 
Infantile glaucoma is called Bupthalmos. It may be hereditary and may affect one or both eyes.
 
 
  • caused by raised pressure inside the eye 
  • aqueous humour drains more slowly than it is produced 
  • slow build up of pressure, person usually unaware of problem until it is advanced 
  • central vision is retained until late in the disease 
  • progressive visual field loss may be prevented by medication 
  • poor visual acuity 
  • impaired peripheral vision and night vision 
  • difficulty adapting from light to dark and vice versa 
  • pain and discomfort 

 

  • nausea 
  • fatigue 
  • weight loss 
  • tingling in the extremities - making reading Braille difficult 
 
 
Macular Degeneration
 
 
 
  • degenerative condition of the cone cells of the retina 
  • loss of central vision 
  • difficulty in discerning fine detail/reading 
  • can affect colour vision, particularly reds and greens 
  • macular vision is lost 
    reliance on 'eccentric viewing'- looking to the side of an object 
  • condition usually stabiles
  •  high magnification needed to aid reading 

 

 
Nystagmus
 
 
 
  • both eyes appear to flicker 
    vision like a 'blurred photograph' 
  • exacerbated by stress, anxiety or fatigue 
  • some people have unusual head posture as it helps maximise vision 
  • difficulty scanning and tracking 
  • problems with depth perception
  •  shifting visual points quickly and effectively 

 

 
Optic Atrophy
 
 
 
 
  • nerve fibres become damaged
  • variable loss of vision or total blindness 
  • affected nerve fibres cannot be repaired 
  • if underlying cause of optic atrophy is effectively treated, damage can be controlled 

 

 
Retinitis Pigmentosa (RP)
 
 
  • rod cells progressively destroyed 
  • initial symptoms include night blindness 
  • difficulty adapting from flight to dark conditions and vice versa 
  • field of vision narrows resulting in 'tunnel vision' 
  • speed and severity of deterioration variable 
  • handheld and stand magnifiers and CCTV's can be useful aids
  •  mobility instruction is often helpful 
  • Cataracts, Photophobia and Glaucoma sometimes associated 

 


 
 
 
 
 
 
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