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
PALs designed specifically for emmetropes:
emphasis to offer maximum _ fields
all (intermediate, near, distance)
_ patients are the most difficult to be successful with
emmetropic presbyopes
freeform is also known as _
digital surfacing
traditional lenses perform optimally only for a limited number of rx powers, optical performance _ as it deviates from that
deteriorates
with digital/freeform progressives, PAL is on _ surface
back
with digital PALs, intermediate and near zones are _, therefore, minimum _ is experienced
wider
swim
seg heights in digital lenses can range in fitting height from _ (used to be _)
11mm, 22mm
freeform power ranges from _ to _, out to _ cyl
+6 to -10, -4 cyl
digital PALS cost:
225-800
What is almost the single most important thing to do when measuring for PAL?
PRE-ADJUST THE FRAME (and take mono PD)
If patient can see near/intermediate with only one eye, but not both together, what is the problem?
Incorrectly mono PD
Seg height for tall patients should fit _
lower
When fitting sunglass PALs, fit seg _
lower
higher add =
_ unwanted cyl
_ near and intermediate zones
more
smaller
(these patients take a longer time to acclimate)
as you go from fixed 11mm to 18mm corridor, the intermediate zone _
grows
you have complete control over intermediate zone with (fixed or variable)?
fixed
variable designs require a _ or higher height
18mm
variable designs sacrifice:
a good transition zone
(soft or hard designs) are easier to acclimate to?
soft
(soft or hard designs) offer largest zones (near OR intermediate)
hard
today’s PALs are a mix of _
hard and soft designs
the only location where prism can be read
Prism Reference Point (PRP)
book on PALs?
Progressive Lens Identifier
what marking is very important?
FITTING CROSS LOCATION
you must know amount of _ when fitting PAL
faceform and pantiscopic tilt, minimum vertex distance too
when fitting PALs, preadjust with _ degrees of _ tilt
8-12, panto
for computer PALs
you need _ measurement
pupils must be within _mm of datum line
near PD
5
for PALs,
avoid _ frames
nose pads are _
deeper is better for _
aviator
good
desirable
always leave _ on PAL when fitting to pupil center
markings
after adjusting PALs, check _ vision, then _, then _
distance, near, intermediate (demonstrate where it’s not usable)
when adjusting a troubled PAL patient, you must _
REMARK THE LENSES
3 magical adjustments for troubled PAL pt:
- increase panto angle
- increase faceform
- reduce vertex distance
