MT2 Material Flashcards
conditions that cause overall field loss (or general constriction)
- glaucoma
- retinitis pigmentosa
- trauma
- proliferative diabetic retinopathy with extensive PRP
- retinopathy of prematurity
describe some characteristics of overall field loss
- only a small central island of vision remains
- pt may not realize until it is 5-10 degrees
- usually a gradual process
- pts will start to show compensatory scanning when field loss is gradual
conditions that cause hemianopic field loss
- aneurysm or stroke (cerebral lesion) most common: think R/L homon. hemi.
- central nervous system tumors: think bitemporal hemi for pituitary tumor
- demyelinating diseases (MS): optic neuritis
- optic neuropathies: think bilateral altitudinal for AION
- head trauma (TBI or ABI)
what does prism therapy help the patient to do?
-prism causes displacement of object in pts blind area to area on retina where there is useful vision (image jump)
prism displaces an image towards the
apex of the prism
one diopter of prism will shift the image ___ degrees towards apex
0.57
what patients are more successful candidates for prism therapy?
- hemianopsias of recent onset
- the better the acuity (macular sparing)
device summary for overall constriction (2 options)
- orientation and mobility
- minification devices (reverse telescopes)
device summary for hemianopic loss
-prism
what is the goal of sector prism for treatment of hemianopic field loss
-to develop scanning skills to provide peripheral information
-to have smaller eye movements needed to see into non-seeing field
an “awareness system” from the diplopic image
what is the downside to Gottlieb prism design?
- due to the alternation between the prism and the rest of the lens, perception can be quite jumpy
- also it is very thick and too far into patient’s visual axis
what are the fitting principles if you do fit Gottleib prism?
- starting point is limbal (if fit is too tight, eye jumps in and out too frequently)
- round (different size segments)
what is the basis behind expansion prism therapy?
how it works, where the prisms are, how much, etc.
- increased field of view with peripheral prism
- 40-57 diopter fresnel
- monocular fit
- superior and inferior
- peripheral diplopia but clear single central vision
describe the fitting process of expansion prism? (steps)
- monocular fit (on side of VF defect)
- upper segment first (demonstrate increased field, training, cleaning and care)
- 2 week adjustment
- lower segment
- 2 week adjustment
- prism ground into lens
when can mirrors be used? (in what type of VF loss)
hemianopic field loss only
but rarely prescribed
how are mirrors (for hemianopic field loss) mounted?
mounted on the top nasal area of the glasses on the eye that has the field loss
(point it towards the field loss)
in a reverse telescope, a patient views through the ___ lens
objective
in what conditions do reverse telescopes work the best
- low powered telescopes (<2.5)
- patients with good VA
- used for sighting
if a patient is using minus lenses for overall field loss, what do they have to do to see the image clearly?
accommodate, use their add, or remove their myopic glasses to see the image clearly
as minus lens is held close to the eye, what happens to accommodation and minification?
- accommodation increases
- minification decreases (tube length decreases)
what are the main categories for Sensory Substitution Devices?
- Audio Substitution
- Relative Size
- Tactile Substitution
what are the 3 types of evaluations we do at clinic for technology?
- 10 minute overview (general overview)
- 20-30 minute technology evaluation (eval of patient’s needs and specific goals, technology only)
- Type one Evaluation (2-3 hours, writing plan for dep. of rehab, life plan on all aspects)
what are some examples of Relative Size devices?
- CCTVs
- Handheld Electronic Magnifiers
what is the proper positioning for a computer or CCTV?
- 20-25 inches from screen
- monitor tilt 10-20 degrees if possible
- test for contrast, magnification, illumination
- watch patient to see if they are looking up, sideways, etc.
what are some features of handheld electronic magnifiers?
- portable, different sized viewing screens
- digital mag from 3.5x - 14x
- freeze frame, several contrast modes
- removable standard battery or charger
- handles, reading stands
- some connect with TVs or monitors for increased screen size and mag
- some can store images
example of a handheld electronic magnifier
Ruby XLHD by Freedom Scientific
examples of portable CCTV’s
- Transformer (computer assisted relative size device)
- Acrobat (stand alone relative size)
- Davinci (stand alone)
- ONYX by freedom scientific
what does an audio substitution devices (standalone) do?
- devices that can be used with Audio only and require no computer interface
- they can be attached to a screen and become a relative size device also
(ex: Clear Reader by Optelec)
what are some Specialty Glasses options?
- Nueyes
- Orcam
- Iris Vision
- AIRE
- Patriot
relative size/ audio substitution computer programs
magnify or read: OCR
- Magic
- Fusion
- Kurzweil
- Open Book
- Dolphin Guide
- Supernova
audio substitution computer programs
- FUSION (Jaws)
- NVDA
- Window Eyes
- Supernova screen reader
- Dolphin guide
sensory substitution programs (voice)
-Dragon Naturally Speaking (dictation software- voice)
list 5 programs you can use:
- FUSION (mag/ OCR)
- Jaws (screen reader)
- Window Eyes (screen reader)
- Magic (magnification/ OCR)
- Dolphin Guide (screen reader)
list 5 programs you can use:
- FUSION (mag/ OCR)
- Jaws (screen reader)
- Window Eyes (screen reader)
- Magic (magnification/ OCR)
- Dolphin Guide (screen reader)
the Light House International sampled older adults seeking vision rehab and what % had depression (both major and subthreshold)
7% had major depression
27% had subthreshold depression
whether a person with vision loss becomes depressed or not seems to depend on:
the impact the vision loss has on a person’s functioning rather than to the actual severity of vision loss
whether a person with vision loss becomes depressed or not seems to depend on:
the impact the vision loss has on a person’s functioning rather than to the actual severity of vision loss
how is Chronic Depression (Dysthymia) described as?
- less severe than major (comes and goes)
- can linger often 2 years or longer
- may be gene/ brain chemical related but majoy life stressors, chronic illness, medications, and relationship/ work problems are often the cause
what are the symptoms and diagnostic criterion for Chronic Depression (Dysthmyia)?
- main symptom: low, dark, or sad mood on most days for at least 2 years (in children for 1 year)
- 2 or more of the following symptoms will be present almost all of the time (feelings of hopelessness, too little or too much sleep, low energy or fatigue, low self-esteem, poor appetite or overeating, poor concentration)
what is Major Depression (Clinical Depression) described as?
- difficult to work, study, sleep, eat, and enjoy friends and activities
- several times in a lifetime
what are the symptoms and diagnostic criterion for Major Depression (Clinical Depression)?
-symptoms that are present every day for at least 2 weeks (fatigue, loss of energy, feelings of worthlessness, guilt, impaired concentration, indecisiveness, insomnia or hypersomnia, diminished interested or pleasure in almost all activities, restlessness, feeling slowed down, recurring thoughts of death/suicide, weight loss or gain)
Generalized Anxiety Disorder (GAD) affects what # and % of the population? how many of those are treated?
6.8 million (3.1% of pop)
only 43.2% are receiving treatment
what does GAD often co-occur with? is there a gender predilection for GAD?
- major depression
- women twice as likely
% and gender predilection for: Panic Disorder
2.7%, women twice as likely
%, gender predilection, and age of onset for: Social Anxiety Disorder
6.8%, equally common in men/ women, typically begins around age 13
%, gender predilection, age of onset for: specific phobias
8.7%, women twice as likely, begins in childhood (average age 7)
% and gender predilection for: OCD
1.0%, equally common, average age of onset 19
% and gender predilection for: PTSD
3.5%, women more likely
% and gender predilection for: Major Depression
6.7%, women more prevalence
average age on onset for Persistent Depressive Disorder (dysthymia)
1.5%, average age 31
anxiety disorders affect what % of children between 13 and 18
25.1%
trends in motor vehicle accident deaths (age groups)
- peaks in 20-24 and older than 70-75
- males> females at all ages
per mile driven, fatal crash rates increase starting at age ___-___ and are highest among drivers ___ and higher
70-74
85
what are some major health considerations with driving?
- Chronic Medical Conditions (cardiovascular, neurologic, psychiatric, metabolic, musculoskeletal)
- Unpredictable Events/ Episodic (seizure, angina, syncope, hypoglycemia attack, sleep attack)
- medications
- vision
is visual acuity strongly associated with relative safety and crashes?
not definitively related to safety and crashes, at best is weakly associated with crash involvement
DMV’s vision considerations for:
Impaired Visual Acuity
-failure to read road signs and/or recognizable hazards in a timely manner
DMV’s vision considerations for:
Impaired Peripheral Vision
- failure to react to a hazard coming from the driver’s far left or far right
- failing to heed a stop light suspended over an intersection
- weaving while negotiating a curve
- driving too close to parked cars
DMV’s vision considerations for:
Impaired Night Vision
- failure to react to hazards located directly in front of the vehicle
- tailgating
- failure to steer when necessary (low contrast features)
DMV’s vision considerations for:
Impaired Glare Resistance/Recovery
.
DMV’s vision considerations for:
Impaired judgement of distance
.
DMV’s vision considerations for:
Impaired eye movements
.
DMV’s vision considerations for:
Impaired visual perception
.
what are some things to consider when designing a Bioptic telescope?
- frame: sturdy and adjustable
- adequate B measurement
- prescription: carrier lens, ocular lens of telescope
- filters
- telescope mounting angle and position
what type of telescope apparatus uses simultaneous vision?
Bita: Bi-Level Telemicroscope Apparatus
what are some Bioptic Telescope concerns with driving?
- vibration causing image instability
- ring scotomas
- jack-in the box phenomena
- duration of carrier to telescope fixation changes
what are some Bioptic Telescope concerns with driving?
- vibration causing image instability
- ring scotomas
- jack-in the box phenomena
- duration of carrier to telescope fixation changes
what training steps would you go through before driving?
- training at home first
- training as a passenger
- driver assessment program (like St. Judes)
- driver rehabilitation OT possibly
do most states allow Bioptic telescopes? what restrictions may they place?
-most states do
-restrictions on VA, VF, Mag, Daylight only
(and can’t be used to meet standard VA requirements)
can states require different renewals based on age?
yes, 1/2 of states have special aged based procedures for renewal
(shorter, in-person, vision, physical, driving test, etc.)
when do states often require you to report to the DMV?
any loss of consciousness, possibly seizures, Alzheimer’’s, etc. but some may just encourage it
what are two formula’s we can use for contrast?
- Weber
- Michelson
as the object size decreases, is more or less contrast needed to see the object?
more
as vision improves, the contrast sensitivity ____ and the contrast threshold _____
sensitivity increases
threshold decreases
as vision improves, the contrast sensitivity ____ and the contrast threshold _____
sensitivity increases
threshold decreases
what is a qualitative measure that is often a better predictor of visual performance than VA
contrast sensitivity
list some contrast tests
- VCTS: Vistech
- Pelli-Robson Chart
- Lighthouse Letter Contrast Sensitivity Test
- Low Contrast Bailey Lovie
- MARS chart
list some contrast tests
- VCTS: Vistech
- Pelli-Robson Chart
- Lighthouse Letter Contrast Sensitivity Test
- Low Contrast Bailey Lovie
- MARS chart
which contrast test tests one size (low spatial frequency) and has 18 different levels of contrast, but can NOT generate a curve unless held at different distances
Pelli-Robson Chart
which contrast test has over 4 spatial frequencies, measures all channels of contrast sensitivity, and can create a contrast sensitivity curve?
Vistech Contrast Test System (VCTS)
which contrast test is for near testing at 50cm, has letter by letter contrast steps, and uses the same letters as Pelli-Robson
-Lighthouse Letter Contrast Sensitivity Test
what contrast test has a standard chart at 90% and reduced chart at 8% contrast
Low Contrast Bailey-Lovie (LCBL)
on the Low Contrast Bailey-Lovie (LCBL) test, what is indicative of below average performance?
a decreased in acuity of more than 0.15 log units (1.5 lines on logMAR chart)
what chart is the MARS chart most similar to?
Lighthouse test, but it has a score report
what are some treatment options for decreased contrast?
- increasing illumination
- using contrast enhancing light filters
- modifying foreground and background colors
- magnification
how does lighting requirements change with age and why?
-needs increased illuminance b/c loss of transmittance and light scatter of short wavelengths
what is the inverse square law of illumination?
illuminance = I / d^2
what are the units for illuminance?
- lux (meters)
- foot-candles (feet)
- watts (W)
when do you have to use the cosine law?
if the light source is not perpendicular to the reading material or surface
what is the cosine law?
illuminance = (cos a) (power of source) / (square of source to surface distance)
what is a greater factor: position of the light or wattage of the bulb?
position of the light
things the patient can use or change about their lighting:
- type of bulb (subjective)
- flexible arm
- metal shade
- position over better eye shoulder
- edge of lamp shade near eye level
- proper angle (subjective)
which type of glare causes discomfort, fatigue, and increases with age
discomfort glare
what type of glare interferes with vision and causes reduced visual performance
disability glare
treatment options for glare
- fit over filters
- tints
- lighting (position, gooseneck arm, metal shade)
- colored acetate sheets (yellow), reading helpers
what 2 companies make fit-over filters and what type of lenses do they make
NoIR and Cocoons
-polycarbonate with numerous tints, but plano lens blanks
what filters are used for patients with Achromatopsia?
reds, magentas, purple
T/F: glare is reduced as the source is moved away from the line of sight
T
pros/cons of Relative Size Magnification (RSM)
pros: can be used in combo with other devices, acceptance b/c large print and increased contrast
cons: limited mag (usually no more than 18 print), limited availability
what is “the process of moving within environment”
mobility
what is “knowing how to move purposefully within that environment”
orientation
what is the Argus II
-special glasses outfitted w/ a video camera and video processing unit that sends signals to a wireless receiver implanted in the eye
requirements for the Argus II
- age 25 years or older
- have RP that has progressed to the point of having “bare light” or no light perception in both eyes
- previous history of useful visual form
- be willing to receive post-implant f/u, device fitting, visual rehab and travel to clinical center
study results of device off vs. device on for Argus II
- object localization (89%)
- motion discrimination (55%)
- discrimination of oriented gratings (33%)
- partial restoration of functional vision- performed statistically better with system on
what is the alpha IMS retinal implant
-sub-retinal implant, available overseas, placed b/w RPE and photoreceptors, a 1,500 electrode stimulates inner retina
what is the brainport V100?
“using tongue to see” using video camera mounter on pair of glasses and flat intra-oral devices with electrodes
(takes training and expertise)
