Final Exam Part 3 Flashcards
Patients with photophobia
Media opascities, retinal dystrophies that affect cones (acromatopsia, C/R dystrophies, some patients with RP), Oculocutatneous albinism, congenital anterior segment disease (aniridia, peter’s anomaly) congenital glaucomas.
Strategies for photophobia
Tinted lenses, polarization, close fitting sunder, brim on hat, use of direct incandescent instead of fluorescent.
Tints that improve VA with cataracts
Yellow to amber that block short wavelengths. May just improve contrast. Does not help reading acuity or performance.
ARMD/DR and tins
Less evidence of improvement with tints. More likely to benefit if cataracts also present. Need to trial and prescribe based on symptoms.
Tints for RP, Chromatopsia, and cone/cone rod dystrophies
Dark amber to Red tints (2-6% transmission)
Albninism Tints
Light amber in room and dark amber in son. Photo chromatic tint with additional 50% amber tint.
Who does driveway work well for
Albinism.
Photosensitivity in RP
May be due to fact cones and rods both affected or that cones become more active once rods die.
Melanopsisn Retinal Ganglion Cells
Respond to light ind. of rod/cone to function on circadian rhythm. Respond to blue light. Slow onset but lasting response.
Noir Medical Technologies
Most comprehensive line of tints.
Cocoons
4 tints but low cost.
Contact Lens optoins
Improve optical correction in nystagmus.
Aniridia tx
opaque soft lenses to create pupil for cosmoses and light attenutation
Achromatopsia/Con dystrophies and cl
Red tint are helpful.
Strategies for Dealing with field loss
Optical (lenses/prisms) or compensatory training (orientation and mobility/ eye movement training for central field loss)
Field loss that can be helped with lenses/prism
General peripheral contraction with near normal VA (RP and late stage glaucoma) and hemianopsia.
Mini faction strategies
Use reverse telescopes. Equal to equivalent power in reverse).
Goal with magnification strategies
Want field of at least 20 degrees and Va no less than 20/100.
Why is bioptic a good option
Since person only needs to access minefield with orienting to a new area.
Why do patients need to adapt to reverse telescopes
Things appear further than they really are.
Ocutech
handheld and bioptic field expansion telescopes
Designs for vision
0.45x bioptics
Conforma
BITA reverse telescope
Cheap reverse telescope
door peep
Optical management of hemianopsia
Sector prisms.
Best hemianopsia candidates of sector prisms
Good central vision, no neglect, good mobility.
Sector prism basics
Need at least 20. Base direction toward field loss. Usually applied to eye with temporal field loss. Can do binocular sector prism if patient has difficult with diplopia. Allows patient to access peripheral field quicker.
Fitting Sector Prism
Begin with fresnel stick on or trial. Place prism edge 2 mm temporal to visual axis. Go on back side if using stick on.
Peli Lens
applied to superior and inferior field. Avoid diplopia and allows view of normal and expanded field. Apply the superior first.
Sector prism training in office
image shift training-have pt. touch images, decreased va (especially fresnel) wayne
sector prism training at home
constant wear, walk in familiar areas first, laser pointing while walking, video games.
Orientation and Mobility training
Help people with severe vision loss to determine where they are (orientation) and how to navigate (mobility). Provided in school up to 21. Provided by commission for the blind for legally blind adults.
When should O&M training occur?
Before the patient with progressive field loss (RP, progressive glaucoma) loses all their vision.
CVA or acquired field loss O&M
Important to put in rehabilitation. Rehab occupation al therapists are skilled in helping patient with acquired field loss lear to scan.
O&M basic instruction
Maximize all senses, self protection, sight guided techniques, cane or other technology, strategies to find direction, Navigate street crossings.
Central Field Loss Help
Patient with new scotooms are generally not aware of the position and size. Awareness of scotoma may aid in establishing a fixation strategy. Your near VF evaluation can be helpful in demonstrating scotomas to the patient.
Training for central field scotoms
Teach them to use PRL (typically inferior or superior to primary scotoma). Do fixations with awareness of stimuli in paracentral field. Saccades with localization (non-reading to reading), pursuit activities.
Services for birth to 18
special education services (21 if developmentally delayed)
Services for 18 and up
Commission for the blind. Other nonprofits.
Commission for the Blind criteria
Must have “legal blindness” criteria.
Birth to age 2 services
Early intervention
Age 3-21
Special education
Commission for the blind services
Independents living services including O & M. Vocational rehabilitation including training on adaptive software and other technology.
Why do early intervention
Allows to level the playing field for kids with VI.
Teachers of the Visually impaired
Training to assist in all aspects of education for children with visual impairment. Usually have 20-30 students and work with IEP. May have specific training for early intervention, Orientation and mobility, deaf blind, brail instruction.
Identification of children who need IEP in Oregon
Must be documented by ophthamoligst or optometrist. Acuity is 20/70 or less in better eye with correction, VF is restricted to 20 degrees in better eye, student has progressive visual condition to reduce either acuity or field to the above criteria. Student is unable to be tested but demonstrates inadequate visual function (use with very young children)
Optometrist’s role for qualifying Children
May not be able to get VA (have lots of tests), In borderline cases or when no VA measurements must see if VI is impacting development or education. Look at other visual dysfunctions like ocular motor control and adaptive skills
Are visual adaptations necessary for the child
Ultimately this is not our call. The special education team determine eligibility. Your information and opinion go into the decision.
How optometrists help education plan
Get them the best LV device, educate those making the decision. Make sure you educate and counsel.
What special ed folks need to know
acuity, which eye dominant, binocular field, is refractive correction helpful, ocular motor restrictions, nystagmus, color vision, contrast sensitivity. Recommendation for education materials, recommendations for LV technology or aids.
Restricted driving
20/50-20/70
Minimum binocular horizontal field
100-140 degrees.
Disability Evaluation
based on VA and field. Report.
Mandatory reporting
Some states have laws you must report someone driving with 20/70 or worse. Not required to inform patient.
Video Magnification systems: desktop units (standard CCTVs)
Provides adjustable magnification up to 50x (best device if acuity worse than 20/200). Comforatable working distance. Can adjust print and background contrast. Can perform other near tasks that require detail vision.
Portable desktops
Work well for students or people on the go (moderate vision impairment.
Disadvantages of CCTV
Expensive, not as portable, Magnification may be effective for patients with central scoots or limited central viewing area.
Portable video magnifers
Moderate magnification. Must consider patients fine motor control. Same contrast as CCTV.
Computer based accessiblity
patient with mild-moderate VI can use built in accessibility options on Windows or Mac OS.
Text to speech options
Almost all printed material is now available in digital formation and reliable software can convert text to speech.
Apple features
Screen magnifiers, text to speech, speakable commands.
IPAD and Iphone
Ultimate technology for mild to moderate impaired. Tactile interface. MAC accessibility plus APPS. Those with vision worse than 20/400 can’t really use.
Bookstore and Read2Go
Gives people with print disability free access to many books. Must verify liability by doctor.
Typoscope
Reading slit to isolate print, reduce reflective glare
Tactile aids
Press on dots. Raised keyboards.
Equivalent power of an focal telescope
zero
Magnification of focal telsecopes
on LIM helps.
Mts
Measured far VA/Demand at far or -fobj/feyepeice
Objective lens
Gathers light from some object. Always a positive lens.
Faster lens
An objective lens that is better at gathering light
Galilean max magnification
4x.
Keplerian max magnification
8x is practical but are available up to 12.
Eyepiece ocular lens
Positive in kleperian and negative in gallean.
Tube length
fobj+Feyepeince
Keplerian Erecting prism
Most have a roof-pecan prism. Made up of two unique prisms separated by air. Light will refract off the prism and some light is lost.
What will you see when viewing through objective lens of kleperian
A fain line bisecting the image. This is a reflection of the roof edge of the prism
Does actual tube length change with klperian
NO. However the physical seperation can be shortened.
Porro Prism
Those used in binoculars. The prism is made up of two right angle prisms offset and roasted by 90 degrees.
Field Lens
Another option when compact size is not an issue. Introduce a third positive lens between the objective and eyepiece lens. This acts as a field stop
Field lens magnification
-1. (i.e. will invert lens but no additional magnification)
Tube length increase with field lens
4x focal length of the field lens.
Stops
Physical structures such as lenses and apertures
Aperture stop
Limits tha mount of light entering the system
Field stop
Limited the field of view of the system
Entrance pupil
Image of aperture stops formed in front of aperture stop
Exit pupil
Image of aperture stop formed behind aperture stop
Entrance port
image of field stop formed in front of entrance stop
Exit port
image of field stop formed behind entrance stop
What about if there are no lenses in front of stop
Then entrance pupil and port is coincidence with stop
What if there are not lens behind stop
Then exit pupil and port equal the stop.
Objective lens
Functions as both the aperture stop and entrance pupil (no lens in front)
Keplerian exit pupil
Formed behind the eyepiece
Eye relief
Distance that the keplerian exit pupil forms.
Maximum brightness with keplerian
occurs when the eye relief matches the eyes entrance pupil (3mm behind the cornea)
How are keplerian telescopes marked
magnification then diameter of entrance pupil
Exit pupil diameter calculation
entrance pupil/magnificaiton
MTS
Entrance pupil diameter/exit pupil magnificaton
Measuring exit pupil diameter and eye releif
Hold at arms length and a light will float behind the eyepiece lens. Can measure them directly.
Brightness and telescope
When a telescope is used to view a true point source the retinal image is brighter but does not increase in size. An extended object will have a retinal image increase in size but may become dimmer because of light loss due to reflection or because telescopes exit pupil is smaller than patient’s pupil
Brightness of Keplerian telescope
Square of exit pupil diameter. i.e. entrance pupil/magnifaction squared.
Reduction in brightness
1-(diameter of exit pupil/diameter of patients pupil) squared
When will there be no dimming with patient pupil
when it equals exit pupil or is smaller
Galilean Telescopes
Exit pupil is formed between the two lenses.
Galilean telescope brightness
Depends on patient pupil as well.
Angular FOV
based on image vignetting of 50%
Real FOV
determined by light rays that pass through the center of entrance pupil and graze the edges of entrance port. Can also say that equal to rays that pass through entrance pupil and graze edges of field stop
Apparent FOV
in image space. deterred by rays that pass through center of exit pupil and gaze exit port (field stop)
Maximum FOV for keplerian telescope
Occurs when telescopes exit pupil is coincidence with eyes entrance pupil. Size of aperture stop, exit pupil, and entrance pupil do NOT limits FOV>
Maximum FOV for Galilean telescope
Max FOV when eyepiece lens is positioned as close as possible to the eye.
Telescope vergence
MtssquareU/1-tMtsU.
When can use use shortcut for vergence
when object vergence or magnification is - or small. V=MtssquareU.
Klperian magniciation
Negative!
Fixed Focus Telescope
Set as focal. Common with spectacle mounted fitting options.
Adjustable focus telescope
Common for handheld or autofocus devices.
Decreasing tube length
Can compensate for low amounts of myopia.
Increase tub length
Can compensate for non zero object mergence (not focal) or hyperopia.
Binocular telescopes
Must have similar RE in both eyes
What magnification can be worn
Less than 3.
Bioptic mounting
Generally in superior portion with the object lens tilted upward about 20 degrees. patient lowers head to view.
Binocular Bioptic
Must have tilting very precise between the two
Contact lens telescope
Patient fit with high minus CL and high plus power lens which functional as galilean telescope. Highest mag is about 1.5-1.7x.
How to get near vision with CL telescope
Move spectacles down nose, including an add in specs, using a separate near spectacle prescription (3D greater than that needed for distance)
IOL telescope
Put in a negative power IOL (along with any hyperopia) and plus spectacles lenses. Can only get 2x.
Intraocular Telescope
Two models 2.2x (24 Fov) and 2.7x (20 for). Must be 75 or older with stable ARMD and cataract. Telescope is implanted in worse eye if VA is 20/200 or better in each eye or determined by patient surgeon if VA in both eyes are worse than 20/200.
Object/Image size comparison for telescope magnification
Use a repeating pattern and subjectively look at difference in size
Entrance/Exit pupil compairsion
Works with kleperian. Hold up and look at light behind the eyepiece.
Lensometer verification of telescope
Place objective lens in contrast with lens rest. Place a high power lens on eyepiece of telescope. Focus the lensometer. Divide the trial lens power by the lensometer reading.
What about if patient prescription is include
Subtract it from V (trial lens power)
What does the Trial lens correlate to?
V.
What is the lensometer reading
U.
Keplerian Telescopes pro
Higher quality optics
Galilean telescopes pro
inexpensive and 85% light transmittance
Disadvantages of telescopes
Reduced FOV, ring scotoma around head borne biopics, need patient training, difficulty to find objects
Galilean telescopes dis
Noticeable chromatic and peripheral abberations
Keplerian dis
relatively expensive and less than 70% light transmittance
When consider binocular telescope
when similar RE and relatively good VA (better than 20/200).
Telescope
Combines a telescope with a plus lens to allow viewing of objects of a finite distance.
Reading cap
considering a thin lens in contact with objective lens
What can a reading cap be
An actual plus lens, a fixed focus telescope with additional plus power in objective lens, a portion of the plus power of the objective lens when tube length is increased for a focusable telescope.
Few with reading cap
Mts X F cap. Technically Mts changes with F cap but this is negligible. Will decrease FOV though
Prescribing a telemicroscope
Determine the near magnification required and equivalent Feq 2. Determine desired working distance=Reading cap 3. Solve for telescope magnification
When working distance is 50 cm or greater
Use focusable telescopes
Work working distance less than 50 cm
use fixed focus telescopes with a reading cap or fixed focus telescopes.
Benefit of reading cap
Cap power can be changed and so working distance can vary. Should only be done with monocular correction.
Advantages of Telemicroscopes
Greater working distance than spectacle lens, Adjustable wd, possibility of binocular correction beyond 10D. Better illumination of reading material possible, heads free with head borne, wide angle telescopes available for increased FOV
Disadvantages of telemicrospes
DOF is critical, Effective field is smaller than spectacles (and smaller with focusable), not good for pt. with constricted fields, Expensive.
Brain Injured patients has ____ in population
Increased in advances in neonatal medical care.
Etiologies of Brain Injury of Malformation in Pediatric poulation
hypoxic/ischemic encephalopathy, trauma (ends or eco)-hydrocephalus to shaken baby, infections or other agents teratogenic agents affecting CNS, Genetic syndromes due to chromosomal or specific genetic errors lead to neurometabolic conditions and CNS malformation
Result of brain inury
Development delay, cerebral palsy/physical handicaps, intellectual disability, seizure disorder, delay/absent language functions, behavior disorder (autism), sensory dysfunction (including vision)
Visual consequences of early brain injury
Poor acuity, VF loss or neglect (both LV), oculomotor dysfunction, optic atrophy, reduced cortical level visual processing ability.
Cortical Vision Impairment
Reduced visual function that cannot be account for by anterior visual pathway or RE OR anterior visual pathway pathology does not account for the depth of visual function reduction.
Leading cause of VI in children
CVI
Manifestation of CVI
Poor and variable attention and performance, inconsistent central fixation, more responsive to peripheral visual stimuli and moving objects, difficulty with figure found, inability to simultaneously process different sensory modes (touch and hearing dominate), severe visual-motor integration disability (looks away when touching object)
What system doesn’t work as well with CVI
parvo
Primary Visual cortex
subconscious processing of the visual scene to make sense to the rest of the brain. Main job is FG and analyzing edges, colors, depth, and contrast.
Visual spatial stream
Dorsal stream to parietal lobe (where)
Visual Identification
Ventral stream to Inferior temporal lobe. What is it.
Visual spatial perception
Dorsal stream directs action. Subconscious analysis of visual scene. Integrates visual information with other sensory and motor input. Determines location of objects and directs attention to allow accurate eye, head and body movement to the object.
What does visual spatial perception dependen on?
Gross and fine motor development. Basis of visual motor integration.
Temporal lobe
in Ventral path. Contains our visual library for face recognition, form recognition, path recognition. Requires functional primary visual pathway, attention to details, direct fixation, accommodation, convergence, sensory and motor integration for confirmation.
Language is
primary vehicle for cementing ID concepts.
Form Perception
Early learning through manipulating of real 3D objects. Gets transferred to 2d representations and language. Difficult for CVI with abstract.
Should you prescribe to CVI patient?
Would the average child get to six years of age and have amblyopia from this? Takes a more significant prescription if patient not using central vision.
VF tx
Help the child accurately scan to make up for the field loss.
How long for LV exam
1.5-2 hours
Space for LV practice
Need a quiet area to demo LV aids.
Documation with Low vision exams and coding with Evaluation and management.
- > 50% of visit must be spent in counseling 2. total time 3 describe content of counseling or coordinated care
Billing for extended time with Low vision exam
Can bill if exam more than 29 minutes
Physical Medical Code
Used for OTs and PTs but can be used by OD. Bill for each 15 minutes of contact. Bill for any rehabilitation that occurs (i.e. learning how to use tools)
Rehab Vision Therapy
Such as teaching to use EF or VF awareness or using training to regain independence.
Rules for use of physical medicine
Patient must be able to improve, goals are defined, must discontinue if no improved over 2 visits, cannot be over 8 visits in 90 days. Must see doctor at least once every 60 days.
Mark up for LV aids
50%
What is photophobia occur in those with cone dystrophies
Melanopsin absorbing ganglion cells.
How does a red filter help
Stops transmission of blue light. Also helps rods from hyper saturation
What did tint study find worked best
Red tint with 13-17% transmission
Who did not benefit from the red tint
oculocutatneus albinism
What did not have a relationship in scotoma study
Patient age, acuity, stoma size, density, or duration of onset. Location of PRL.
What develops spontaneously with bilateral central scotomas affect fovea
One or more PRL. Normally it is right next to the scotoma. Can also have multiple PRL
Are scotomas typically symmetrical in ARMD
NO. They are asymmetrical.
How many patients were unaware of their scotoma?
56%
How may were aware of their vision disapeearing
44%
Why did they select real prism
ease with mobility
why did they select fake prism
more comfortable vision.
Acuity Reserve
The size that can be ready comfortably.
what acuity predicts you will get down to 1m
0.85 logMar
Higher acuity reserves are associated with
better aided acuity
Do guidelines need to differ between LV cause?
No.
Contrast sensitivity for 1 M reading
must be 1.05 or better
Mean acuity reserve
2x
Those with low aided reading acuity have ___ acuity reserves
low
Those with great aided reading acuity have ____ acuity reserves
large
reading speed and low vision aids
Will read as fast as they do clinically. Not affected by lv aid.
