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Retinal dystrophies. Marion Blazé. The retina. M ade up of Rod and Cone Photoreceptors Rods are good at 'seeing ': things that move in the dark in black and white in less detail. The retina. Cones are good at ‘seeing’: things that are still in daylight - PowerPoint PPT Presentation
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RETINAL D
YSTR
OPHIE
S
MARION B
LAZÉ
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THE RETINA Made up of Rod and Cone
Photoreceptors
Rods are good at 'seeing':things that movein the darkin black and whitein less detail
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THE RETINA
Cones are good at ‘seeing’:
things that are still
in daylight
in colour
in fine detail
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Umbrella term:
Refer to problem with the
rod and cone photoreceptors
Failure to recycle – damage to tissue
The photoreceptors either do not
work from birth or slowly stop
working over a period of time
What is Retinal Dystrophy?
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What is Retinal Dystrophy?
Includes:
Retinitis pigmentosa
Cone dystrophy
Rod monochromatism
Rod-cone dystrophy
Cone-rod dystrophy
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Retinitis pigmentosa
in ‘pure’ form, only rods affected
progressive
may retain good central vision
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Retinitis pigmentosa
onset usually 8 to 18 years
first symptoms, night blindness or ‘clumsiness’
‘Cock-eyed’ by Ryan Knighton
syndromes – Usher’s, Lawrence-Moon, etc
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Cone dystrophy
Cones affected
Classic form – Stargardt’s (‘Look out Marcus!’)
Presentation usually after age 6
Progressive
Usually retain peripheral vision for mobility
Sometimes diagnosed incorrectly
Night vision can be better than day
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Best’s disease
Also know as ‘vitelliform macular dystrophy’
Rarer than Stargardt’s
Presentation usually later
Progressive but macula may be spared
Usually retain reading vision
Some become legally blind from complications
- macula scarring, retinal detachment
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Rod monochromatism
Non-progressive retinal dystrophy
Totally colour-blind
Very photophobic
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Rod-cone dystrophy
Rod effect more prominent
Like RP
Progressive
May lead to total blindness (in forties)
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Cone-rod dystrophy
Cone effect more prominent
Like ‘reverse RP’
Progressive
May lead to total blindness (in thirties)
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Educational implications
To do with functional vision rather than diagnosis
Peripheral lossmobility affectedneed good lightmagnification perhaps detrimentalmight lose sight of things
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Educational implications
Central lossoften need lower light levelsmagnification requiredeccentric viewingshouldn’t rely on colour
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