Unit 4 Flashcards
What is low vision or visually impaired
-Significant vision loss that cant be corrected with glasses or contacts, medication, treatment or sx
Moderate visual impairment
20/70 to 20/60
Severe visual impairment (legally blind)
20/200 to 20/400
or a visual field of 20 degrees or less
profound visual impairment
20/500 to 20/1000
or a visual field of 10 degrees or less
WHO - meaning
world health organization
WHO classifys near total visual impairment as..
less than 20/1000 or a visual field of 5 degrees or less
WHO classifys total visual impairment as..
no light perception (NLP)
WHO classifys functional visual loss as..
when an individual is unable to see well enough to perform the activites of daily living (ADLs) needed to survive
Disorders associated with low vision
-cataracts
-glaucoma
-macular degeneration
-retinal dystrophies
-diabetes
is vision loss slow or fast with cataracts?
Slow, gradually progressive process
How to help vision when you have cataracts
-A change in gls rx may be helpful up to a point until sx is required
-Sx removal of the cataract and insertion of a lens implant
what are other symptoms of cataracts besides blurry vision?
glare around lights
difficulty with night vision
color distortion
what causes cataracts?
-age
-diabetes
-smoking
-excess alchohol use
-eye injury
-prolonged use of corticosteroids
-prolongers exposure to sunlight or radiation
types of cataracts
-age related cataracts
-traumatic cataract
-radiation cataract
-congenital or pediatric cataract
-“secondary cataracts” PCO / capsule thickening (happens after cataract sx)
what are 3 kinds of age related cataracts?
-nuclear sclerotic
-cortical
-posterior subcapsular cataract
what is secondary cataract
-occurs after cataract sx
-called a posterior capsular opacification
-most common complication after cataract sx
-capsulotomy performed with YAG laser
prevention of cataracts
-UV protection
-protective (safety eyewear)
-quit smoking
-diet (Fruit, veggies, leafy greens, whole grains, nuts)
treatment of cataracts
-updated gls rx
-brighter (increased) light
-anti glare coating (Cut down light scatter / glare )
-magnifying lenses
-sx
types of lenses
-monofocal
-extended depth of focus (vivity)
-multifocal
PCO - posterior capsular opacification
-film or haze that forms on membrane/behind lens implant after cat sx
Refractive lens exchange
cat sx procedure but without the patient having a significant cataract
-Done mainly for refractive puposes (ppl that dont qualify for LASIK, PRK)
-RLE often used for “self play” procedures
ex px has very early cat but wants to “que jump” to have it removed before its “riped”
Glaucoma
-Causes vision loss and blindness by damaging the optic nerve
-second most common cause of blindness worldwid
hallmarks of glaucoma
-loss of peripheral vision
-high intraocular pressure
-optic nerve damage
can glaucoma be irreversible?
if left untreated it is irreversible and can result in drastic visual field loss
glaucoma treatment
-medication
-laser treatment (trabeculoplasty)
-surgery (trabeculectomy)
retinal dystrophies
degenerative diseases of the retina
-Retinitis pigmentose is the most common
what is retinitis pigmentost
-low vision and legal blindness occur from as early as childhood to as late as the fourth decade of life
-at this time, there is no specific cure or treatment for RP
what does retinitis pigmentosa affect?
-the light receptor cells
1. Rods
-loss of vision begins in the periphery
-causes problems with night vision
2. Cones
-responsible for central and color vision
-affected later
treatment for retinitis pigmentosa
-low vision aids
-correcting other eye problems (refractive error, cataract)
-experimental treatments (gene therapies)
type 1 diabetes
lack of insulin
type 2 diabetes
not enough insulin
-insulin is not working properly
types of daibetes
-type 1
-type 2
-gestational diabetes (during pregnancy)
risk factors of diabetes
-length of time w diabetes (more than half of ppl w/ diabetes will develop DR)
-uncontrolled diabetes
-high blood pressure
-high cholesterol
most common eye disease in diabetics
diabetic retinopathy
diabetic retinopathy
-significant cause of blindness in adults of working age
-can be progressive and usually affects OU
-worsens if blood sugars are uncontrolled
-
symptoms of diabetic retinopahty
early stages usually dont have symptoms
changes may come and go
proliferative retinopathy
-most severe stage
-growth of leaky blood vessels, vitrous hemorrhages lead to severe vision loss or blindness
macular edema
-collection of fluid in the macula
-can occur in every stage
-causes blurred and/or distorted central vision
-resulting in difficult w. reading and daily activites
treatment for diabetes
-early stages
(moniotring)
-later stages
injections (anti-VEGF)
laser treatment (PRP)
sx (vitrectomy)
macular degeneration
-results from damage to the macula
blurs central vision
makes it harder to see faces, read, drive
-May not notice vision loss in early AMD
DRY Macular Degeneration
(nonexudative)
-Drusen - tiny yellow/white deposits in the retina
-Results from the eyes inability to dispose of water products
-Can be hard, small and scattered
-Can be large, soft, and closer together
-No treatment for late dry AMD
-Special dietary supplements may be able to stop intermediate AMD from turning to late AMD
geographic atrophy
the main cause of vision loss in dryMD
vitamins for macular degeneration
-vitalux
-AREDS 2
WET AMD (exudative)
-affects only 10-15% of ppl who have AMD
-vision loss is due to bleeding and leaking of abnormal blood vessels as well as scarring
-treated using intravitreal injections that inhibit the growth of new, abnormal blood vessels
symptoms of macular degeneration
-early dry AMD doesnt have any symptoms
-intermediate dry AMD may be associated with mild blurriness in central vision or trouble seeing in low light
-Late AMD can cause straight lines to appear wavy or crooked
risk factors of macular degeneration
-age 55+
-family history
-race (Caucasion)
-smoking
how to lower risk for AMD
-quit smoking
-get regular physical activity
-maintain healthy blood pressure and cholesterol levels
-eat healthy foods (leafy greens)
reduced contrast sensitivtity
-the ability to disinguish between finer and finer increments of light vs dark
altered colour vision
-some disorders are associated with specific color vision changes;
-blue/yellow loss in retinal disease
-red/green loss in optic nerve disease
-blue/yellow loss in early glaucoma
Optical low vision aids
-magnifiers
-specs
-bioptics
-telescopes
Non optical low vision aids
-special lighting
-talking devices
-audio books
-plastic typoscope signature guide
-large print calendar
-talking tape measure / talking scales
-liquid level indicator
keyboard label
-stick on foam dots
-orange tape
-braile
-apps
Magnifiers
-Need to ask what near activites they enjoy
-Remember: The more plus power the short the working distance
-Adaptation can be challenging
Hand held magnifier
-Must maintain proper focal distance
-half way between the matieral and the eye
stand magnifier
rests on page and is moved across reading material
page magnifier
lies flat on page, enabling hands-free use
Dome magnifier (brightfield)
magnification 4x power
lens diameter; 65mm
-distortion free lens
Prismatic spectacles
-range in power +4D to +10D and include base in prism in OU to help the px converge easily
-the prism power is typically two more than the dioptric power of the spec
-+10D will have 12 base In in each eye for a total of 24PD
-the stronger the lens the closer working distance is required
what are bioptics
-they are miniature telescopes mounted to the top of eyeglasses
how does bioptics improve vision
make the image larger and lets many low vision individuals see clearer and further away
video magnifier portable
-full HD camera
-3x to 15x magnification
OrCam MyEye
-consists of a camera that is affixed to gls
-3 main functions
1. reading text
2. product recognition (describe objects, colours, barcodes)
3. facial recognition
-helps visually impaired know what is around them
OrCamRead
costs less but is only used for reading
-used for ppl with mild low vision, reading fatigue and reading difficulties -including dyslexia
-reads text aloud
important tests to establish levels of low vision
-VF
-contrast sensitivty
-glare testing
-color vision
-extraocular muscles
-pupil evaluation
vision testing for low vision pxs
-important to get the most accurate VA (may take more time)
-using charts such as ETDRS, bailey-lovie, feinbloom
-ETDRS is considered the best due to its standardization
(equal letters per row, spacing of letter and spacing between rows)
-
refraction sequence may need to be altered for low vision pxs by using…
-often using a trial frame instead of phoropter
-use larger steps when changing lenses
-use high powered JCC lenses
diff types of VF tests
-confrontation
-compuarized (automated)
-goldmann perimetry
conditions that can affect contrast sensitivty?
-cataracts
-posterior capsule opactiy (following cat sx)
-glaucoma
-refractive sx
-diabetic retinopathy
-Contact lenses
what can be done for pxs with contract sensitivty?
-ensure appropriate lighting conditions
-use of high contrast colors to label commonly used items
-accessibility functions on smart devices, bold text, reverse contrast
-appropriate filters for outdoor glare
examples of vision aids to help improve contrast sensitiviy?
daylight floor lamp
-acetate yellow print enhancer
-fit over polarized sunglasses
glare disability
decrease in vision that occurs when glare causes a reduction in contrast between the background and the object of regard
-generally caused by some sort of media opacity
how is glare testing done
-with a brightness acuity tester or brightness acuity meter
-using several diff levels of glare
examples of low vision aid to reduce glare
-plastic typoscope signature guide
-black/grey polarized
Types of extraocular muslces
-Covertest / if px can fixate for cover testing, may be limited to
-Hirschberg
-Krimsky
Hirschberg test
-light is shone from 33cm away and the cornea light reflexed are observed
Krimsky test
-way to approximately measure strabismus
-horizontal/vertical prism is placed over the deviating eye until both reflexed are central
schedule follow up appts for low vision pxs
to assess adaptation and effectiveness
initally every 3 to 6 months to monitior progress and make neccessary adjustments
