Test 1: Optical and Non-Optical Devices Flashcards
first visit at MCO
review consulting letters and questionnaire - understand goals
perform exam to understand function - VA, VF, CS, know better eye or binocular, consider conventional spectacles, predict starting magnification
demonstrate devices and near goals
ocular health screening
loan useful devices
second and subsequent visits
review how the loaned devices helped or why they weren’t successful
demonstrate more devices to help goals
device training of final devices recommended - record time spent face to face with patient
order devices
dispense devices
prescribing rational
case history - tasks VA - level of magnification VF - limitations CS - lighting needs monocular - better eye binocular - fusion possible refraction - conventional bifocal vs SV optical devices
optical device categories
microscopes magnifiers telemicroscopes telescopes electro-optical
optical characteristics of devices
magnification
FOV
working distance
mobility
each optical system has its own optical characteristics
advantages and limitations of each optical system must be appreciated relative to the functional properties
which devices or functional optical properties will help your patient
microscope (chart)
mag 8-48D
FOV largest comparable
work distance shortest comparable
mobility generally precludes
magnifier (chart)
mag 2.5x hand, >5x stand or pocket
FOV adjustable, personal comfort
work distance adjustable, personal comfort
mobility portable, acceptable
telemicroscope (chart)
mag 2-8x
FOV smallest comparable
work distance longest comparable
mobility generally precludes
telescope (chart)
mag 2-10x handheld, 2-6x bioptic, >10 binoculars
FOV small, hand largest, bioptic smallest
work distance not applicable, distance use
mobility full field precludes, bioptic ok
electro-optical (chart)
mag 2-60x
FOV larger and faster processing
work distance more normalized
mobility precludes
telescopes
hand-held clip on spectacle mounted - bioptic, full diameter, miniaturized binoculars CL designed intraocular lens designed intraocular telescope
telescopes FOV
smaller field of view with greater mag adequate FOV with powers 10x less than 6 deg FOV not practical larger FOV with shorter vertex distance keplerian have larger FOV than galilean compensate law of optics by making telescope physically larger
handheld telescopes
hand occupied
mobility less restricted
powers up to 10x
variable vertex distance - with or without glasses, affects FOV
bioptic telescope
hands free
smaller size reduces field
mobility less restricted
powers up to 6x - can go higher but not feasible
may include refractive error in telescope
most expensive
full field telescope
mounted geometrical center of frame larger diameter - larger FOV precludes mobility powers up to 8x may include refractive error in telescope varied cost
clip on telescopes
full field characteristics removable affordable powers 2-4x wear habitual glasses longer vertex distance increased weight instability
binoculars
physically bigger larger FOV better light gathering capability consider when power needed is greater than 10x usually has at home
telescopes
rule of thumb handheld 2-10x full field 2-8x bioptic 2-6x binoculars 2-18x
telescopes formula
to calculate mag needed - dist VA/desired task size at distance
telemicroscopes
intermediate distances handheld clip on binocular spectacle - geometrical center monocular spectacle - geometrical center bioptic mounted bifocal position
handheld tele microscope
appropriate for tests at intermediate distance 20-100 cm
focusable or fixed focus
very small field of view
if a reading cap is built into the scope - set working distance if nonfocusable, determined by internal lens, 4D cap = 25 cm fixed - focusable 25 cm and closer
hands not free
mobility not affected
difficult to master
clip on telemicroscope
intermediate tasks small field of view optics internal (not a cap) focusable or fixed at near mounts in geometrical center - full field mounted, heavy poor centering monocular mobility not a factor
binocular tele microscopes
intermediate tasks
binocular spectacle - geometrical center usually, full field mounted, may mount as angled bifocal, can order monocular, may include refractive correction
internal optics or cap - 20-100 cm working distance, cap determines working distance - 2D to 6D
mobility a factor
hands free
small field of view
same as a surgical telescope
bioptic mounted telemicroscope
telescope mounted above the frames geometrical center - bioptic position, may include correction
lens is a frame referred to as a carrier - corrects refractive error
hands free - move head to position scope
mobility possible
smallest field of view - small diameter
internal optics or a reading cap - cap converts telescope to intermediate or near use (telemicroscope)
telescope with a reading cap
is a tele microscope
determining magnification and working distance of a telescope with a reading cap - focal distance of the plus cap dictates the working distance 4D=25 cm
total power of tele microscope is the power of the telescope times the magnification power of the cap
4x telescope with 6D cap
4x (6D/4D) = 6 x or 24D
6D cap gives 16.6 cm working distance
24D microscope gives working distance of 4.16cm
microscopes
full field half eye executive bifocal round segment bifocals press on bifocals loupes uncorrected myopia high plus contact lens fresnel lens
full field microscope
larger diameter largest field of view necessary close working distance 2-20 cm power 2x to 15x - 12.5 to 1.7 cm generally monocular may correct refractive error precludes mobility - swim effect
half eye microscope
half a lens
less field of view
close working distance
binocular - powers 4D to 16D, with base in prism - 4D has 6BI, 8 D has 10BI
monocular - powers 2x to 12x may correct refractive error
no distance correction
limited mobility
bifocal and clip-on microscopes
executive, round, press-on - smaller diameter, reduces field of view, close working distance, more mobility, powers 1x to 6x, distance correction
clip-on - larger diameter and field of view, WD longer due to loupe holder, removable for mobility, powers 1x to 12x, affordable, peak/AGFA styles available
microscope magnification factors
power of a microscope in X equals diopters divided by 4 - 25cm used as relative distance
20D lens provides 5x magnification
formula for calculating magnification needed to read 1M (20/50) V=MxD = mag needed in D to read 1M
magnifiers
handheld pocket stand illuminated or non-illuminated - handheld, stand, pocket dome/bar
handheld magnifiers
hands aren't free find focal point (focused) difficult if tremor powers practical to 20D - >20D difficult to maintain focus variable working distance portable mobility not a factor affordable illuminated or non illuminated
pocket magnifiers
very portable powers 5D to 56D use for short term tasks - spotting affordable mobility not a factor find focal point variable working distance difficult if tremor
stand magnifiers
fixed focal point
ease of use - even if tremor, arthritis, etc.
diverging rays - requires 2.5D accommodation or bifocal to clear image
powers 8-60D
hands not free
mobility not a factor
use for longer reading tasks
illuminated magnifiers
handheld, pocket, stand
often preferred vs non-illuminated devices - improves reading, especially if reduced high contrast frequency
incandescent, halogen, LED available (LED most popular)
stand magnifiers magnification
D/4 +1 = power for european devices
dome and bar magnifiers
fixed focal point not diverging rays affordable powers 2D to 6D hands not free type of stand magnifier
electro-optical devices at MCO
primer/max magni-cam acrobat/transformer CCTVs merlin pebble
primer and max with track
handheld mouse
magnicam
better handheld mouse magnifier
transformer/acrobat
kind of like a projector
CCTVs
closed circuit TV
so expensive so a lot of patients want it used
enhanced vision merlin
has OCR - text to audio
VES autofocus telescope
Jordy was the first one but no longer made
far view by optelec
distance and near both
freeze frame and then magnify capability
computer magnification/accessible reading
zoomtext magic lowbrowse victor stream kindle/nook ipad/android tablets
the iPad as a visual aid
app list handout use of iPad as a magnifier using apps pinch and drag function reverse contrast voice over and verbal texting applevis.com
accessible technology
cellphones - jitterbug, apple iPhone, knfbReader mobile (nokia) takes photos then reads text
non-optical devices
reading stands typoscopes tints bold writing pens lamps
tints
glare reduction - grey (decreases contrast), amber (increases contrast), any other to lesser degree
enhanced vision - yellow, red, orange, amber, red (color deficiencies achromatopsia), magenta (blue cone monochromatism), blue (rod or retinal dystrophies, RP)
NOIR
corning and chadwick
lamps
incandescent
fluorescent
natural
Ott light / Verilux
non-optical rehabilitation products
clocks drop dispenser remote measuring cups watches all kinds of stuff
