Susan J. Leat, PhD, FCOptom, FAAO

ProfessorSchool of Optometry and Vision Science, University of Waterloo

Rhiannon Verran, BSc, OC(C), COMT

Low Vision Specialist,Vision Loss Rehabilitation Nova Scotia

Niki Harper CVRT

Independent Living Skills/Low Vision,Vision Loss Rehabilitation Manitoba

©Copyright: Susan Leat, Rhiannon Verron, Niki Harper

Outline

• EV• Training with optical devices▫ Near▫ Distance• Electronic devices and training

Eccentric viewing training – for central scotomas

Eccentric viewing : the use of a retinal locus other than the fovea for fixation (preferred retinal locus= PRL).

After training = TRLEccentric viewing : the Pt is conscious of

looking “to the side”Eccentric fixation : the Pt is not conscious of

looking off centre. The visual system has become re-referenced.

scotomas come in all shapes and sizesPRLs develop naturally with time (within

6 months)>50% not aware of using it>50% change their PRL during 6 months

but reading speed not affectedNaturally, PRL is more often below the

scotomaPRL more often to the left of the scotomaMultiple PRLs are common

Crossland et al. Ophthalmology 2005;112(9):1579–1585.

Purpose of eccentric viewing training?? To make patient aware of their scotoma to develop consistent and efficient use of a

PRL to speed up the process of developing a PRL to optimise PRL position

When does a patient need EV training?

• Central scotoma in both eyes ▫ AMD▫ Macular scar▫ Macular edema• Inconsistent fixation• Poor response to magnification

• Established “rightward” eccentric viewing• Established “downward” eccentric viewing

• When VA measurements indicate

Or with near charts

• SK Read

• Or poor response to magnification

Available from Precision Vision

Determining the direction of EV

• Clock Face Method

• Steps:▫ Have patient look at the clock▫ Ask them if they can see the picture in the center

▫ Some may say the star is clear, but some of the numbers are blurry or have disappeared

▫ If client reports this, walk them around to clock to see in which position the star becomes visible

▫ This will establish the eccentric viewing position

• Face Method▫ Once a PRL is determined, have the patient look

at your face▫ Ask if parts of the face are missing or blurry▫ Have them apply what they’ve learned with the

clock, to looking at your face

Measuring the visual fieldA protocol for eccentric viewing training

1. Determine size, position and shape of central scotoma Amsler or Modified Amsler Tangent screen or Modified tangent screen Humphrey Microperimeter

Want fixation to be central during field testing - plot blind spot to check fixation

• Mr M. field

Amsler

Markowitz, S, (2015) Ophthalmology Management, : 19: 48-50, 76

If symmetrical scotoma, move fixation upwards ie. orthogonal to direction of text If scotoma not symmetrical, choose area of best horizontal

field extending to the right which is nearest to fovea Pt must move fixation in the direction of the scotoma

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Teach EV

• Awareness training • Identify best EV location (I use the clock)• Practice fixating on new PRL and scroll print

into that fixation point, ▫ Do not add magnifier until they’ve shown success• After client has demonstrated success, give

homework to client and book follow up before they leave. • Depending on client’s performance, follow ups

required

Teaching eccentric viewing

can begin with Amsler chart use isolated letters then small words to teach EMs to

eccentric location

Quillmans (or similar) exercise

Pt moves eyes in appropriate direction until letters are legible.

EV video

4. Home training training sheets with range of print sizesmust have a helper if word reading acuity is poor loan a 16-20D

magnifier.

After 2 weeks teach steady eye strategy (scrolling)

had one red two my dog tree for ten blue

had one red two my dog tree for ten blue

After 2 more weeks reassess word reading acuity and magnification prescribe LVA

If no success see Pt again after 6 months

• Questions about EVT Where? Effectivity? Few RCTs of effectivity, especially compared to

other TxWould people develop just as good PRL

themselves? How many hours? Technique? Monocular versus binocular viewing Is the increase in reading speed enough?

Gaffney et al (2014). How effective is eccentric viewing training? A systematic literature review. Ophthal Physiol Opt 34, 427-437, Stelmack et al (2004) JVIB, 41, 729-738.

• What about microperimetry with biofeedback?▫ Verdina et al; trial of microperimetry with audible

feedback = 1 line improvement in VA in Stargardt’s But no evidence of randomization

▫ Vingolo et al (2007): Cohort study, audio biofeedback in AMD RS improved from 25 to 45 wpm character size decreased 36 to 12 point print

▫ Vingolo et al (2013) Compared two types of feedback. Improvement in reading speed and VA with luminance

feedback RS improved from 46-54 wpm

Verdina et al (2013) Eur J Ophthalmol. 23: 723–731., Vingolo et al (2007) Appl. Psychophysiol Biofeedback 32:185–189. Vingolo et al. (2013) Appl Psychophysiol Biofeedback 38: 11–16. .

▫ Limitations RS still slow Quantitative differences between fovea and peripheral

retina▫ Why? Oculomotor control? Crowding Decreased visual span Slower temporal processing Slower speed of information transfer - bottleneck

Cheong et al (2008) Vis Res 48, 577–588

• RCT comparing stand CCTV and EVT▫ Patients with AMD▫ With appropriate spectacle Rx and optical mag▫ 2 sessions of EV training vs desk mounted CCTV

(22” Clearview, Optelec)▫ Significant improvement in reading speed and

decrease in time taken to read utility bill for CCTV, but not EVT

▫ Significant improvement in near VA with own glasses with EVT (but VA still 20/400)

▫ Concluded that CCVT more effective for reading but EVT still important for low VA tasks e.gshopping, O&M, grooming etc,

Leat, Si, Gold, Pickering, Gordon, Hodge Accepted for publication in JVIB.

Near optical devices• Optical considerations for hand magnifiers

▫ Hold close to the eye to get the best FOV

▫ If using without a reading addition, distance makes no difference to magnification (EVP)

▫ If using with a reading addition, hold CLOSER to the eye get more magnification (EVP) AND hold the magnifier as far as possible from the page.

▫ Single and double aspheric lenses

• Optical considerations for stand magnifiers

▫ Distance from the eye is more restricted – depends on reading addition

▫ Ideally prescribe by the MT ≠ Manufacturer’s mag.

▫ If patient pulls the SM away from the page, add is too low or EVP is too low Change to a stronger SM

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• Optical considerations for microscopes

▫ Object at focal length of MS (for a presbyopicemmetrope) Closer for an uncorrected myope Further for an uncorrected hyperope

▫ So not much opportunity to vary the distance

Near Optical Device Training

• Working distance; The closer the magnifier is held to the eye the better the field of view (do they have a near prescription?)• Positioning (parallel to plane of paper)• Changing batteries and bulbs• Lighting; ask about the conditions of where they

read at home

▫ How to prescribe lighting?

▫ As for tints, use subjective assessment for type and colour temperature and type, and quantity of lighting

▫ Measure illuminance in lux, convert to lumens

Inches from page

cms from page15 20 25 30 35 41 45 50 56 61 66 71 76 81

Light bulb calculator (lumens according to lux required and distance)

Red indicates when more than one bulb may be needed

Scrolling and Page navigation

• Scrolling; reading material is moved from right to left in a smooth continual motion. This allows for the patient to keep fixated on their PRL• Client must have good hand motor control• General tips: ▫ Start with easier material ▫ When you get to end of line trace the same line

back before moving down.▫ You can use your thumb to keep track of your line

-Practical application: Have client bring in a bill for follow up appointment to try applying their skills to something they are familiar with.

-Practice finding top of bill, scanning to right side (to where the amounts are shown) and then scanning down. Look for landmarks or use your finger to mark locations-Using a clipboard for reading tasks allows the client to have more control

Telescope training

• Localizing and Spotting; Have the client find something big enough they can see unaided. Fixate on this and position telescope to see the details • Focusing• Localising• Scanning; Find a light pole and have the client

trace the pole with telescope to find the street sign

Electronic devices

• Electronic Magnification▫ Desktop CCTV models▫ Portable electronic magnifiers▫ Handheld video magnifiers• iOS devices

• Tabletop CCTV systems

• Portable electronic magnifiers

• Handheld video magnifiers

• iOS Devices▫ iPhones/iPads have given

independence to blind and partially sighted individuals

▫ Basic features can be turned into low vision devices Users can take a picture

using the camera and then zoom in to see more clearly

The flashlight can be used in low light to help with contrast

Accessibility features for iOS devices include:• Siri• Magnifier• Font Adjustment• Invert Colors and Grayscale• Zoom• Dictation• Speak Screen

• Voiceover

Siri

• Siri is a hands-free assistant who can help users send messages, place phone calls or even flip a coin.

• To activate, press and hold the “Home” button. Once you hear two quick beeps, Siri is ready, and you can ask her to do a task.

Magnifier

• Once activated, once the home button is hit three times, the magnifier app appears

• It turns the phone’s camera into an electronic magnifier with options for turning on the flash, changing the colors, zooming in and out and taking a snapshot

Font Adjustments

• Font can be adjusted in the following ways:▫ Larger text▫ Bold text▫ Increase contrast

Invert Colors and Grayscale

• Inverting colors and using grayscale can help to improve contrast

Zoom

• Zoom magnifies the entire screen• Once activated, you need

to double tap with 3 fingers to zoom• To navigate the screen,

you must drag with three fingers

Dictation

• When you press the microphone button on the keyboard, you can dictate and the words will be automatically typed into the field

• Siri must be activated for dictation to work

Speak Screen

• Speak screen will read text on your device in email, iMessages, web pages and books

• Once activated, you need to swipe down from the top of the page with two fingers, or tell Siri to Speak Screen

Voiceover

• VoiceOver is a gesture-based screen reader that allows an individual to use iOS even if they cannot see the screen • When activated, VoiceOver

describes everything happening on the screen• Simple gestures allow the

user to navigate the device• Dragging your finger on the

screen tells you what is there• Tap to hear descriptions• Double tap to activate

Apps

• iBooks/eReader apps▫ iPads/iPhones can be used as an eReader▫ Font sizes can be enlarged and brightness can be

adjusted