Dyslexia & Visual Stress Flashcards
1
Q
What is important to bear in mind with dyslexia and visual stress?
A
- If have dyslexia, you don’t have to have visual stress
- Educational psychologist is the person who diagnoses px with dyslexia – they may then suggest for px to be seen in visual stress clinic
2
Q
What is the incidence of dyslexia?
A
- Between 10-20% of population of school children
- Often missed – and may be picked up quite late on
- No uncorrected deficiencies in hearing &/or vision (& no other related problems)
- Discrepancies between intelligence & reading ability
o Dyslexia is not a barrier – no bearing on intelligence - Often children overcompensate & mask symptoms
3
Q
Which factors would alert you to screen for dyslexia?
A
- Dyslexia present when all other aspects of development are normal but reading/spelling delayed
- Many of features of dyslexia are found in normal readers in early stages of development of readding
- Primarily a literacy difficulty with difficulty converting letters into sounds
- Other cognitive processes may contribute to difficulties but are not the root cause – attentional processing for a range of processes may be affected
- Few factors that would alert you to get px fully screened
4
Q
Describe reading difficulties (Phonology) and dyslexia?
A
- Poor alphabetic coding skills as observed in deficient ability to learn & make functional use of letter sounds & redundant “spelling units” to decode words phonetically (e.g. “at” in cat, fat, rat)
- Deficient ability to identify (name) words as wholes as observed in letter by letter, sound by sound approach to word identification & a general tendency to be overly analytical
- Poor alphabetic coding skills & poor ability to identify words as wholes
- Depending on how px has been taught to read – may be able to mask it
5
Q
Describe processing problems and dyslexia?
A
- Most severely impaired readers are deficient in alphabetic coding
- Smaller percentages tend to be deficient only in whole word identification or only in alphabetic coding
- Most severely impaired readers are deficient in both alphabetic coding & whole word identification
6
Q
Describe ‘reading with the brain’?
A
- Broca’s Area
o Speech-sound awareness (phonological processor)
Frontal area - Angular Gyrus
o Sound-symbol associations - Wernicke’s Area
o Language comprehension (context & meaning processors)
o Need to hear sound, put it together with word, need context to word – e.g. red is that specific colour - Occipital Lobe
o Letter & letter-pattern recognition; storage of printed word images (orthographic processor)
o Lets you work out meanings of words – pattern recognition – words you can’t sound out & need to have seen before
7
Q
Describe signs and symptoms of visual stress?
A
- Visual processing deficits
- Visual perception & spatial confusion deficits:
o Perceiving letter & words as reversed forms (“seeing” b as d or was as saw); general spatial orientation problems
Problem with visual perception – may look at something too quickly & miss letters – gets 6&9 mixed up – may not be dyslexic at all and just get these mixed up - Imperfect representation of letters, spelling patterns & whole words & poor memory for visual detail. Template matching
o They may just make the odd error
o Varying degrees of dyslexia
8
Q
Describe visual processing difficulties?
A
- Oculomotor deficits:
o Eye movements/saccades, conversion & fusion defects that impair form perception & left to right scanning
o Evidence suggests this is trained, poor ability therefore likely to indicate lack of practice
o Need smooth eye movements to be able to read
o Making multiple saccadic eye movements in order to read – go to next line – go back & check a word
o If impairment in oculomotor system then this can impair reading - Magnocellular (transient system) deficit
o Fast processing, temporal or timing responsibilities, smooth pursuit, eye movement control, BV control, timing of saccades but not stimulated by high contrast – role in reading
o Magnocellular cells – motion – ability to process this - Noise deficit theory
o Over activity in cortex interferes with processing, lack of ability to inhibit cortical processes – too much activity in brain
o This can be improved with coloured overlays to reduce the “noise”
o Cant switch off noise – cant concentrate
Too much noise on page – not able to calm everything down that looking at
Noise becomes movement in visual area – not just black on white page
9
Q
How does vision afffect reading?
A
- Dorsal & ventral stream
o Ventral stream allows discrimination of shapes & objects
o Dorsal stream responsible for visual guiding/grasping at objects - Dorsal at top (green) – ventral at bottom (purple) – primary visual cortex (blue grey)
- 80% of learning is done through vision
- 40% of brain is dedicated to processing visual input
10
Q
What ae the structures in the brain and eyes involved in reading?
A
- Dorsal visual stream – where pathway – lets you pick something up
- Ventral visual stream – what pathway
- Corpus Callosum – cross over between right & left side of brain – need both sides working together
- Magnocellular cells
- Oculomotor control – vital
- Binocular vision – monocular px does not always have dyslexia – not being able to use 2 eyes together may impede reading
- Fixation control
- Visual perception – what is it you are actually seeing
11
Q
Why is vision so important in children?
A
- Blurry vision can affect ability to see letters & words accurately
- Discomfort or pain may make reading unpleasant (& therefore may avoid reading/studying)
o If pain when reading then wont read – can impede development in school etc - Poor vision may affect motivation since comprehension poorer therefore does achieve goals of reading
- Frustration
- Already compounds other errors made during reading
12
Q
Describe visual stress/Meares Irlen Syndrome?
A
- Visual Stress is also knowns as Meares-Irlen Syndrome
- Condition generally refers to reading difficulties, light sensitivity & headaches from exposure to disturbing visual patterns or print distortion
o When these pxs look at black words on white page – they may not see words but they see the pattern between the words
o But they can still read 6/5 on your chart
o Not a visual problem is a developmental problem - Visual discomfort & perceptual distortions & benefit from colour are sometimes collectively referred to as ‘visual stress’ or ‘Meares-Irlen Syndrome’ & sometimes as ‘Irlen Syndrome’ or ‘scotopic sensitivity syndrome’
13
Q
What are common symptoms of visual stress?
A
- Moving words on a page
- Jumbling of words
- Poor Convergence
- Poor accommodation
o Use dynamic ret to find out if px accommodating or not
o Use RAF rule to find out range of accommodation
o If poor accommodation then will struggle to read – we can fix this - Diplopia – may need exercises
- Asthenopia – eye strain, frontal headaches, sore eyes – headaches worsen with day – wont wak px up in night
- Headaches mostly frontal
- Skipping words on the page – px tells you this
- Losing place frequently – px may need to use ruler to read straight
- Struggling to copy from the board - Reader moves/wriggles a lot!
- Etc etc!!!
14
Q
What to do when child is struggling?
A
- Keep visual stress in back of mind – tried everything else and not working
- Are the seeing normally?
- Look for subtle problems
15
Q
Describe the full orthoptic/BV assessment in child with suspect visual stress?
A
- Fixation and alignment – do they have a problem of heterophoria control
- Binocular status
o Rule out any BV problems – that is easier to fix
o Check binocularity – can they maintain it when they read, distance – how good is there fusional control - Fixation Disparity – if px has slight phoria you’ll find it on this
- Convergence – jump and push up
o If problem with this then can be barrier to fluid reading – cant keep focus at 33cm & will have uncomfortable viewing - Accommodation, amplitude, facility and accuracy
o Facility is ability for px to exert accomm – within a minute – put minus lenses up (e.g. -2.00) & get them to look at distance target & get it clear (accommodate through it) – see how many times (cycles) px can accommodate through it if have lag, ciliary system will start to tire - Fusional reserves – if not enough fusion then will be a barrier to reading if have a heterophoria that will break down
- Saccades – can train this to help this system
- Smooth Pursuit
- Tracking
- Dynamic Retinoscopy
o Do on all pxs with suspected blurred vision & problems reading
o Have they got a lag of accomm? Less ciliary muscle tone - Rate of Reading Test with and without colour
