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How much vergence is induced at 6m?
How much vergence is induced at 4m?
Why is there a need for relaxation of accomodation
- consulation anxiety in some px
- induced vergence at 6m
What is the range of testing with the HIC?
- sphere: normal chart
- cyl: 2 vert fan charts
- balance: isolate 6/9 letters
- mono endpt
- Chevron=tips, blocks=wings and tips
- add fog
- used for high cyl and keratoconous
- long pinhole- blur circles contracted
- fog, rotate for bv, reduce fog, rotate 90, reduce for bv deduce cyl
how do cyclopegics work?
paralyse ciliary muscle and iris constrictor papillae
When would you use cyclopegics?
- px reports ast but no apparent rx
- unstable endpts in rx/ret
- convergent strabismus
- sig esophoria
- low accom amp
- obj more positive than sub
how much deviation of accom is ok before worrying?
20% from expected amp
cyclo results- what action should be taken when +0.50, +1.00?
- 1. nothing
- 2. psuedomyope/ latent hyp
What is the average result of cyclo? hyp/myp?
- dry rx+0.50
- more plus
- more minus
what are some problems with cyclo?
- increase aberrations
- reduces dof
- alters accom-conv
- toxic/allergic effects
- incon to px
- lens prescribed cant be worn for long
Tentative add at 20, 44, 60 yo?
10, 4, 0 loss of 1D every 4 years
For prolonged viewing how much amp is used?
- normal- 1/2
- young- 2/3
- ill- <1/2
What lighting is used for FCC and UFCC and why?
- room light/ no additional light- increase depth of focus= less blur
- this is how they would read with at home
Procedure for testing a presb patient
- Entering vision: unaided VA/ habitual VA, habitual near VA, amp of accom
- Obj Rx: ret
- Subj Rx: refine sphere, cyl, +1.00D test, balance
- Near: UFCC, FCC, NRA, PRA, linear range of clear vision
At what cyl does spectacle effectivity change for near vision?
Near cyl method?
- reduced snellen chart+ JCC- clc retina- spher from FCC
What is an adequate fog for near JCC on 20yo?
what is UFCC?
balance accom for near without convergence
Value for UFCC in young adult?
- established accom employed relative to testing distance (with convergence)
- near base
Value for FCC in young adult? why difference from UFCC?
- convergence acting, less accom required
- how much the px can relax their accom
- elderly have none so no relaxing
NRA norms in young adult?
- not +10 since that is monocular, cant get that much at 40cm
How much accom can exert
PRA norm in young adult?
in a pre-presbyopic px, where is nra/pra taken from?
in a presbyopic px, where is nra/pra taken from?
Linear range of clear vision?
- dioptric midpoint
- carried out last
- chart out then in
What caution should you take when prescribing a psuedomyope?
- limit -ve lenses!
- try an add instead! :)
- review in 6 months
What clues are there to exposing a psuedomyope?
- asthenopia more severe
- intermittance distance blur
- reduced/varible va
- low amp accom fr age
- more minus on subj/ret than normal
- ret fluctiations
- minus lenses dont provide much clarity
- clinical history of anxiety
- bv abnorm
what risks are there when it comes to hyperopes?
- strabismus/ amblyopia in children
- what stage should you prescribe?
What is the problem with hyperopic children and ast
- low a causes more asthenopia
- larger a= px gives up trying
Should 0.50DC be prescribed?
- old- yeah may need it
- if sphere is rly huge
- must be able to improve vision couple of letters
never ______ prescrbie cyl!
over, always lesser cyl value
what counts as anisometropia in hyp/myp/ast?
What considerations need to be amde for anisometropia?
correct dominant eye to best va
what is meant by the apparent early onset of pres?
- latent hyp becoming manifset
- only give px 'reading' glasses
- do not over correct add
how to treat an amblyope?
- aniso: fully correct good eye
- and mpmva amb eye
- BV training
- full rx BE goal in stages
- BV training
Cutoff considerations for child age 1
- myp: -3
- hyp: +4.5
Cutoff considerations for child age 3
- myp: -1.5
- hyp: +3
Cutoff considerations for child age 5
- myp: -1
- hyp: +1.5