Progressive Lenses Flashcards
with progressive lenses, instead of hard ledge, the curve _
gradually slopes off from top to bottom (results in unwanted astigmatism)
add power can be measured _
with lens clock (not ideal way)
astigmatism contour plot shows distribution and amount of _
each lines represents _D
cylinder
0.50
mean power plot:
mean power =
sphere + 1/2(cyl)
mean power plot shows magnitude and distribution of _
plus power change
eye-path power profile is a graph of _
power from fitting cross, through channel, and near zone
eye-path power profile reveals _ at 95% of add
shows _ of near zone power
corridor length
stability
on eye-path power profile, x-axis=_
y-axis=_
add power
distance above or below vertical center of lens
design parameters for progressive lenses:
base/add power
corridor length
near zone width
distance zone characteristics
the ultimate progressive:
distance viewing like SV
8x35 intermediate
executive near zone
no blur
if wide, clear distance produces:
hard line along 180, excessive astigmatism below 180
wide intermediate produces:
cyl in distance, extra-long corridor
extra wide reading area produces:
excessive blur, swim sensation, short channel not very functional
_ area is most critical, patients are more sensitive to blur during this viewing
distance
soft designs produce:
cyl in distance, extra long corridor
in high add powers, near zone _ dramatically; distance confinement _
decreased; increases (also gets smaller)
rotational PALs:
_ lens for both eyes,
used by _
same
twisting
multidesign PALs
- one design fits all
- manufacturer prescribed lens
family design:
_ designs, patient sticks with one
specific lifestyle
consistent (4)
PALs designed specifically for hyperopes: reduced _ especially at _ makes _ zone extra wide to achieve this, put extra cyl at _
visual field
near
near
distance
PALs designed specifically for myopes:
clear _ is most desirable
usually don’t need width at near due to minifying effect
to achieve this, put extra cyl at _
distance
near
