Week 7 RF-Reading with central vision loss Flashcards
How does what you’re looking at effect the quality of detail?
- Directly looking at something = high detail
- Further out to the side/periphery from where you’re looking = much less detail/visual acuity
What is the size of the Macula and Fovea?
■ Macula (5.5mm) (give us sharp vision)
■ Fovea (1.5 mm) – greatest visual acuity (inside the macula and gives greater visual acuity)
■ Rods (Roughly 91 million cells) – dark adapted vision, low acuity
■ Cones (Roughly 4.5 million cells) – colour vision, high detailed vision, high acuity –
located in the centre of the macula
What is Age-related Macular Degeneration
(AMD)?
■ An eye disease which results in a loss of central vision – Macula
■ Macula is responsible for central vision / high detailed vision
■ Results in severe vision loss / blindness
■ Typically affects aged 50+
■ Causes: Unknown
■ Risk Factors: Smoking, genetic, poor diet
■ Treatments: Aim to stabilise vision (wet
macular degeneration, eye injections) (does not cure this however, just slows the rate of losing vision) used for Wet AMD not Dry AMD
How does Dry AMD become Wet AMD?
- Waste products (drusan:yellow lipid products) collect under the macula and disrupts the normal function of the retina (it thins the macular causing blurry vision)
- New blood vessels grow behind the retina, causing swelling, bleeding, scarring and rapid vision changes.
-This affects everyday life and reduces the quality of it (e.g., reading is a big issue).
-Dry AMD always leads to Wet AMD causing central blindness (cannot see centrally but peripheral vision intact aka aschotoma)
What is the Eye-movement system? (the oculomotor pattern)
-First will make a fixation (directly looking at the word)
-Then make a saccade (rapid change of eye movement) to jump to the next word
-Re-fixation is going back to look at the word
-We sometimes skip a few words but if we need to go back we do a regression
-A return sweep is a large regressive saccade (i.e., moving back to the start of the sentence but the next line).
What are the characteristics leading to successful reading?
- Need highly detailed (central) vision for accurate perception of word form
- I.e. need to make a fixation on (almost) every word
- Make short saccades between the words
What are some characteristics of oculomotor pattern?
- Fixations ~200ms
- Most words receive at least one direct fixation
- Skipping words ~20%
- Saccades ~15-40ms, ~5-9 chars
- Mostly progressive
- ~10-15% regressions
- = average reading speed ~250-350wpm
Visual Impairments: What is Macular Degeneration?
- Most common cause of legal blindness
- Loss of central vision
- Visual distortion (metamorphopsia) (wavy blurry words)
- Fixation instability (can’t fixate on the word as they can’t see)
- Counterproductive attempts to foveate
What is Eccentric Viewing?
■ A technique training the individual to direct their eye in a different position to see clearly and avoid their central scotoma.
■ Trains the brain to understand what it is
seeing using a different region of the
retina.
■ Using a Preferred Retinal Locus = area
of the retina that gives the best visual
acuity.
■ Individuals get training to use a different
region of the retina to see.
What is Horizontally scrolling text?
- A line of horizontally scrolling text from right to left.
- News ticker, train board announcement.
- Dynamic text to support eccentric reading (Harvey, Walker & Anderson, 2019).
- Reading depends on sequence of *fixations and saccades (Findlay & Liversedge, 2000).
What is Rapid Serial Visual Presentation (RSVP)?
One word is presented in the centre of the screen one after the other at varying speeds.
RF: What is the purpose of the research?
To evaluate the potential of dynamic text formats (horizontal scrolling text and RSVP) as a way of enhancing reading with CVL by supporting effective use of the EV reading technique.
RF: What are the methods of STUDY 1: SIMULATED CENTRAL SCOTOMA?
- Fifteen students (11 female), 18 to 32 years old (mean age, 20.40; SD = 3.94)
- normal or corrected-to-normal vision (best-corrected binocular visual acuity of 0.0 logMAR or better) (because they wanted to remove their central vision ethically)
- spoke English as their first language
- no language or reading deficits (self-report)
RF: What is the apparatus of STUDY 1: SIMULATED CENTRAL SCOTOMA?
- 1920 × 1080-pixel monitor
- Viewing distance = 70 cm
- An EyeLink 1000 remote desktop-mounted eye-tracker recorded pupil and corneal reflection from the right eye at a sample rate of 1000 Hz (prevented central vision)
- The Experiment Builder program included custom Python code to mitigate some of the known limitations of gaze-contingent paradigms attributed to pupil size changes due to blinks
RF: What is the design of STUDY 1: SIMULATED CENTRAL SCOTOMA?
-RSVP
-2 static text presentations (press space bar for next sentence)
-Multi-line paragraph format
-Asked participants to promote eccentric viewing and look below
RF: What is the procedure of STUDY 1: SIMULATED CENTRAL SCOTOMA?
- LAB based – eye-tracker
- Speed of text – Previous pilot – aimed to match speed
- Participants read standardized passages of text (YARC Secondary) presented in each of the four text formats – passages of text were randomized
- Participants given practice passage before reading task
- Participants informed about eccentric viewing technique and to adopt this to the best of their ability
- Participants read aloud – scoring reading errors
*Comprehension questions completed after
RF: What are the measures of STUDY 1: SIMULATED CENTRAL SCOTOMA?
- Reading performance (comprehension + errors) measured with each text
display with artificial scotoma - Comprehension – Literal (1-2 words), Inference (had to elaborate), Summary (had to summarise text), Total (total of each section)
- Adherence to eccentric viewing technique with each text display except multiline
(ROI analysis).
RF: What are the results of STUDY 1: SIMULATED CENTRAL SCOTOMA? (eye-movement behaviour)
- Majority of fixations made with static and
scrolling text located on or below the text - Fewer fixations at the upper EV location
- Ability to hold gaze at the EV location -
better in the RSVP condition than for the
static or scrolling sentences. - Participants found it very difficult to avoid
making fixations onto the text despite the
presence of the central scotoma. - For all four text formats, the participants tended to shift gaze onto the text
- Scrolling text and RSVP text, the participant’s eye movement behaviour was
broadly similar to that observed for reading
without a CVL. - For the static text formats, many more leftward saccades were made to reinspect the text - suggesting that a horizontal scanning strategy had been used.
RF: What are the results of STUDY 1: SIMULATED CENTRAL SCOTOMA? (reading performance)
- Literal comprehension better with RSVP than static texts, Scrolling better than static
texts, no significant differences
between scroll and RSVP - Inferential Comprehension – significantly better with scrolling text and poorest with
RSVP - Percentage of key points remembered significantly better with scrolling than other
text displays - Overall comprehension better with scrolling text display
RF: What is the participant sample of STUDY 2: MACULAR DEGENERATION?
- Diagnosis of Wet / Dry macular degeneration + CVL in either (RE, LE, BOTH)
- English as first language
- 37 participants (32 female, 5 male)
- Mean age = 77.54 years and SD = 10.89
- Mean years since diagnosis = 8.68 and SD = 5.14
- Six-Item Cognitive Impairment Test (to rule out dementia and Alzheimers)
- Exclusion criteria = ocular comorbidities and any language, reading, or cognitive impairment.
- All participants aware of EV technique.
RF: What is the apparatus of STUDY 2: MACULAR DEGENERATION?
Same as Study 1 EXCEPT:
* Conducted in own homes
- YARC Primary Passages of text used
- Static / Scrolling = iPad
- RSVP = Samsung (custom coded in-house app)
- Static text (SL+ML) - PowerPoint
- Horizontally Scrolling text – MD_evReader app
- Scrolling text given before RSVP text (practice session ONLY)
RF: What is the procedure of STUDY 2: MACULAR DEGENERATION?
- Binocular-distance visual acuity obtained
using the Bailey–Lovie Visual Acuity
chart (used in general eye tests) - Near visual obtained using Digital
MNRead app - Font size based on MNRead digital
reading test - set as two times each
participant’s critical print size from the
digital MNRead - Practice passage given – speed of text
set, RSVP and scrolling matched
RF: What are the results of STUDY 2: MACULAR DEGENERATION?
- Overall reading comprehension better with scrolling than all other text displays, F(3,108) =13.02, p < 0.001, and η2G =
0.18. - Higher proportion of errors observed for the RSVP format (mean = 11.39%, SE = 2.76) than for all other text displays (scrolling text display mean = 1.35%, SE = 0.38; single-
line static text mean = 2.13%, SE = 0.69; multiple-line paragraph format mean
= 2.82%, SE = 0.69).
RF: What are the summary and conclusions for both studies?
STUDY 1
* Adherence to EV in the simulated scotoma group was poor
* Adherence to EV was better with RSVP BUT resulted in poor comprehension and accuracy
* Static text and scrolling lines - participants adopted a strategy of scanning around the text itself and appear to have been reading by recognizing words on either side of the central scotoma
* Reading performance - best with the scrolling text format (cannot be attributed to better adherence to EV with a simulated CVL)
STUDY 2
* BETTER reading performance with scrolling text than with static text
* Reading performance POOR overall with RSVP
CONCLUSION: We suggest that studies of reading should include MORE than one
measure of performance, and that scrolling text may support effective reading in
people with CVL and as such has potential as a reading aid.
