Non- optical devices Flashcards
Types of non- optical devices for LV px
Glare and filters Typoscopes Image enlargement Copy-holders and clip-boards Writing guides and black marker pens Information Lighting Contrast enhancement 
why could u get glare and photophobia
could be due to pathology: • Corneal pathologies • Retinitis pigmentosa • Albinism • Diabetic retinopathy • Macular degeneration • Glaucoma • Uveitis • Cataract
what are the different types of glare
– Disability glare:
Impairs the patient’s visual performance
– Discomfort glare:
Light within the visual field causes discomfort
– Reflection glare
E.g. reading a shiny book
– Dark adaptation: problems
Difficulty when moving from light to dark
– Light adaptation:
Difficulty when moving from dark to light

manage photophobia and glare
Treatment of the underlying cause Reduction or removal of light source/scattered light Blocking the light source using shields, visors, hats etc Changing position Tints Typoscopes
what’s a disability glare
– Increase in contrast threshold due to scattered veiling luminance across retinal image
– Short wavelength cut-off filters e.g. UV absorbing filters
may benefi/ poloroid filters
– Shade or broad brimmed hat vital (car sun visor effect)
– Contrast enhancement
this will improve visual acuity, visual comfort and mobility skills

Whats a discomfort glare
no effect in VA
Broadly neutral tint (neutral density filter affects all
wavelengths equally)
– Photo-chromic grey or brown (Transitions)
– Hilco drop-in behind the lens grey filter
– No gain from short wavelength blocking filter e.g.
yellow Hilco drop-in filter
– Shading has less effect but still valuable
px difficulty adapting dark/light
filters
moving light- dark- can use a grey filter- lower the adaptive state of retina when going back to light
problem dark-light- cone dysfunction? u could use red filter- to minimise rod bleaching
whys a typoscope goood
Reduce back scatter
Can increase reading rate and fluency with media opacities
Self made and commercially available from RNIB and banks
Same effect as negative contrast (white text on black background) on CCTV (EVES)
large print
magnification device doesn’t have to be as high-
so easier to use magnifying device swell
however limited tuff in big print, heavy as more pages, limited books available. can also use bigger font size/bigger screens
Disadnavtage- printing is expensive-time consuming- waste of paper-
remember acuity reserve
software for pcs
speech outback cursor and mouse enhancements reverse display magnification hands free scrolling
keytop stickers
lettering of keys bold and bigger so u can orientate urself on the keyboard
clip board /copy holders
to hold page steady and flat is a big help
comfortable wd
easy to obtain
cheap
writing guides/ black marker pen
to write
enhnace contrast
training>?
where can ur px get info from
HES local orgnisations rnib partially sighted self help groups eye contionleaflets interenet
lighting should be localised and portable
low energy fluorescent- high initial cost- bbut cold light source, uniform white light, low running costs
whereas a tungsten light may be more cheaper to begin with, it has higher running costs, gets more hot.
