Dispensing Final Flashcards
Which factor is normally NOT considered essential in fitting th progressive add
Specificying the nasal rotation of the ptrogressive channel
The fitting cross for a general purpose ptorgressive addition lens would be fitted higher than specified by the lens manufacturer in what condition
The progressive is used to inhibit accommodative esotropia in children
when children are fin with ptrogressive addition lenses, yet still have the ability to accomodate just as other children do, the fitting cross is usually fit
4mm above pupil center
Children fitted with progressive addition lenses should not wear those lenses for sports or play ? T or F
False
Progressive lens fitting crosses should be set lower for the first-time wearer to aid in adapting to the lenses T or F
False
Prism is verified at a different locationo n the ptrogressive add lens from where the distance Rx is verified? T or F
True
The fitting cross is at the major reference point? T or F
False
A synonym for major reference point is?
prism reference point
If a progressive lens design changes as ad power changes, the lens is called a mulitdesign lens? T or F
True
Adaptation to progressive addition lenses involves changes in the respective eye and head movements used in fixation
True
Although all of the factors listed below are important in the fitting of ptrogressive addition lenses, which factor has the most influence on wearer satifaction
fitting accuracy
In practice the power of the near addition is seldom measured when verifying progressive lenses
True
What method for viewing the hidden markings on a progressive addition lens is NOT suggested
Hold the lens so that its surface may be viewed in a mirror by reflected light
A frame has been selected for a progressive addition lens wearer. Some of the parameters of the frame and frame fitting are listed…..What would be considered problematic?
The laboratory order form specifies a binocular distance PD of 65
The frame is an aviator shape
When a wearer does come back with a compleain, the most straighforward wat to check for possible problems is to first put the progressive markings back on the lenses and see if they are correct in relation to where they shoul be when the rx is worn? T of F
True
Unwanted peripheral cylinder power in a progressive add lense, increases how?
Increases as the add power increases
Compared with a soft design, a hard design usually provides a wider area of high visual acuity in the distance portion of the lens. T of F?
True
Progressive power can change from distance to near zones in either a rapid or slow fashion. If it changes in a rapid fashion, then what will not occur?
The near zone is generally smaller
Distance and intermeidate and near zone widths influence each other. When one zone is made larger or wider, teh other two zones will become narrower or smaller? T of F
True
Contour plots record the surface elevation for the front surface of a ptrogressive addition lens. T or F
False
What is not demonstrated by contour plots
The expected increase or decrease in chromatic abberation throughout the lens
What lens design is more likely to have higher amoutns of peripheral astigmatism
Hard design
Would a prgoressive add lens with a spherical upper front surfaces be more likely hard or soft?
Hard
Is a progressive addition lens specifically designe for frames with a narrow B dimenstion more likely to resembel a hard or soft design
Hard
Is a presbyoopic emmetrope who is used to crystal clear distance vision more likely to complain about a progressive addition lens with a hard or soft design
soft
Whihc lenst type does NOT requrie free-form type of lens generating to make the lens
Progressive made as semifinished lenses and completed in labratory
Position of wear lenses are able to correct or comepensate for all but which of the following?
It can correct everything vertex distance panto change base curve induced cyl/sphere
near variable focus lenses have a powere degression..Degression is??
The range in power of a variable focus lens from the total near power of the lens to the power found at the top of th lens
Near variable focus lenses are used for small office environments, and all have 50% of the add poewr in the upper portion of the lens? T of F
False
Near variable focus lens design will be used for presbyopes with all differnt amounts of add power. How many power ranges do near varialbe focus lenses have for each particular brand?
1, 2, 3…as man as there are add powers
Suppose a variable focus lens made by a certain manufacturer comes with a recommended power range of 1.25 fore weares who have a +2.25 add. This particular wearer has a distance correction of -0.50 +0.75 x 090 for OD and OS…and an add of +2.25.. What pwere would be verified in the upper portion of the lens?
+0.50 +.75 x 090
A near variable focus lens has a +1.25 -0.50 x010 power in the upper portion of the lens. It has a power of +2.75 -0,50 x 010 in the lower portion what is the degression (power range) of the lens?
+1.50
Near variable focus lense are all fit exactly like standard progressive addition lenses, measuring monocular PDs and placing the fitting cross under the pupil?
False
No occupational progressive lenses meant for small offices and computers come with distance powers in the top of the lens-onlyintermediate powers? T or F
False
Usint the rule of thumb for prism thinning of progressvie addition lenses how much prism thinning would be expected for the follwoing
+3.00 -0.75 x 090 add +2.25
-3.00DS ad +1.00
1.5pd BD
None required
+3.00 -0.75 x 130
add 1.50
what prism thinning should be giving?
0.75pd
For progressive addition lens how much yoked BD should be given
-3.50 -0.50 x 180
add +2.00
none
Lenses are surfaced in a finishing Lab? T or F
False
which type of lens has the same power over the entire lens
Single vision lens
What term is a synonym for a finished lens?
Uncut lens
A frame tracer is often used in conjuction with?
a lens blocker
Of the steps in lens fabrication, which process occurs last?
Edging
What is the proper steps in the edging process?
Find lens axis and MRP location, Centration, Blcoking, Edging
When spotting a single vision lens for edging in reference to edged lense orientation the lensmeter ing dots will be on?
the cylinder meridian
Whigh point should always appear either exactly in front of (or somewhat below) the wearer’s pupil
geometric center
If there is no prescrived presim in the prescription, what point will not be the same?
NRP
Horizontal pattern size is measured horizontally through the central hole in the pattern? T or F
False
For a plano cylinder, light passes through the ( ) meridian undeivated
Axis
The longer the wavelentht of the UV rays, the greater the likelihood of biologic damage? T or F
False
Single, high-level amounts of UB radiation can be damaging, but the eye is able to recover from long-term, low level amounts of UV exposure with out being affected? T or F
False
A persons ability to work effectively under a situation of reduced illumination increases with age? T or F
False
Coatins for plastic lenses are purely for scratch resistance and have no AE properies
False
When a int and an AR coating are both desired, plastic lenses should be dyed before the AR coating is appleid?
True
Although in certain instances acuity may increase when a 10% neutral-density filter is worn in bruight sunligh, persons older than age 40 years experience poorer vision if the filter is darker than 10%
True
Normal transmission for average sunglasses runs between 15% and 30%
True
Exposure to sunlight over an extended period of time will reduce the time needed for the eye to dark adapt
False
Yellos tints help nighttime driving becuase they eliminate blue haze
False
With AR coatins, it is possible to have any one of a range of reflex colors or no color at all and still produce an efficient coating
True
The quality of the AR coating is not indicated by the eveness of the reflex color of the coating
False
An AR coating will make a lightly tinted lens perform better at night than it otherwise would perform with the tint but no AR coating
True
The process of adding an AR coating to a tinted plastic lens sometiems chanegs the color of the tint
True
AR coating the back surface of a pair of sunglasses is not advisabel because it lets more light throught the lens
False
An AR-coated lens is best cleaned in office by using an ultrasonic cleaner
False
An AR coated lens is helpted by use of an antifog or antistatic agent
False
Mirror coating provided good prote tion from sunlight if combined with a tint but allows more UV and IR than a nonmirrore coated lens of equal transmission
False
What type of light is an AR coating most effective against
light entering straigt on
An antiscrath coating is usually affected by exposure to antitfog and antistatic agents
Flase
UV or color dyeing a plastic photchromic lens makes the pthochromic aspects of th lens work better
False
Lense that absorb the short end of the visible spectrum may help reduce some types of glare
True
In denoting the amount of light absorbed by the lens, if numbers such as 1,2,3 are used, the higher the number the more light is allowed to pass the lens?
False
There is no such thing as a glare control dye
False
Glare control type lenses will not cause a decrease in scores on standardized color testing for color dectives
False
For neutral gray glass sun lens of plus power with the tint in the glass, as plsu power increases??
the transmission decreases
Which UV radiation has the longest wavelength
UVA
What ocular condition is associated with with increasing severity with increased sun exposure
Cataracts
Glass blower’s cataract is believed to be caused by?
IR radiation
A light pink tint is good for?
Even absorption across the visible spectrum
A yellow ting is good for?
Adviasable for night driving
Skiing
increased contrast
Gray tints are good for?
God for color defectives
Green tints are good for
Highest transmissions of visible light found in the middle of the visible spectrum
Poor IR absorption is associated with?
Dyed plastic lens
Tint varies with thickness??
Tinted glass
A color deficient individual will readapt to the induced color changes for which of the following lenses?
NONE
As a secondary effect, antiscratch coatings will??
reduce lens reflections
what is the most effective method to use when attempting to match a new glass photochromic replacement lens with an older glass phtotchromic lens?
Reharden the old lens with the new
A person has new lenses and has been wearing them for a month. SHe now decides she would like to have them AR coated. THe lenses are lightly scratched. IF the lenses are then AR coated??
Teh scratches will be more evident
A pair of glasses with SRC lenses is best adjusted using?
a forced air warmers
Disregarding impact resistance and taking only transmission characteristics into consideration which method is best for hardiening a photochromic lense
chemical temper
What color lens is “Kalichrome H”
Yellow
the tint may be remoced and reapplied for which types of lenses
vacuum coated and plastic
What lenses should not be AR coated
Lightly tinted glass lenses
sun lenses
glass photchromic lenses
-can all be AR coated
The problem of annoytin internal lens reflections occurs most often in?
Low minus powered clear lenses
what contributes to the rapid darkeingin of a photochromic lense
UV, Previous exposrues and cold
A polarizing ophthalmic lens should be orientated so as to eliminate
horizontally vibrating waves
A prescription ground polarizing lens is characterized by
a stretched sheet of polyvinyl alcohol
when inserting a lens, if success is not achieved on the first try, heat the fram and the partially inserted lens together, then push the partially inserted lens the rest of the way into the bevel?
False
The lower eyewireof the frame is rolled forward when the lense is inserted. After several attempts to straighten it and reinser the lens, the forward rolled eyewire still reamisn a problem. One solution is to straigten the eyewire and try inserting the lens from the back
True
If salt from a solat pan sticks to the frame, what ma be done to alleviate the problem
Add talcum powder to the salt
A pair of edged multifocal lenses are helt back to back. Their segemtns overlap exactly. WHich of the follwoing statements hould NOT be made?
The cylinder axes are correct
There will ne no unwanted vertical prism in the prescription
The best way to heat nylon frames is ??
hot water
what type of frame may be heated until it bends under its own wight
Optyl
what frame materials shrink when plunged into cold H2O
cellulose acetate
propionate
What fram materials may shring when heated
polyamide
which frame material do best by cold snapping the lenses into place
polyamide
carbon fiber
polycarbonate
Types of frames that do not adjust well are?
polycarboanate
carbon fiber
polycarbonate frames neither stretch nor shringk when heated
True
A paire of frames is labeled Optyl. the temples have metal reinforcing running the length of th temples. These temples ??
Do not require very much heat before adjusting
To remove lenses after a cellulose acetate frame is heated, it is easiest to push a lens out by placing the thumbs on the?
Back side of the lens inferiro nasally, pushing the lens with the thumbs while pulling the eyewire with the fingers
Eyewire closure pliers are used?
to close the eyewire of a metal frame around the lens to allow for lens size evaluation
When restringing a nylon cord mounting, the ends of the cord are threaded through two holes in the nasal and two holes in the tempral side of the fram. WHich hole is threaded first?
The cord is always threaded through the lower hole first
We are inserting a grooved lens in a nylon cord frame. The nylon cord is the correct length and in the mounting. Now the upper part of the lens is pressed into the upper eyewire of the frame. WHen this is being done, where should the cord be?
On the front surface of the lens
To get the end of a nylon cord out of the groove mounting when it is stuck in the groove, the best thing to use is?
a dental pick
When the cord of a nylon cord fram has lost its elasticity, remove the lens and heat the cordthis will shrink the cord, retightening the lens. THe lens will remain tight almost as long as it did after first being inserted?
False
WHen the lense is complegely inserted into the frame bevel, yet the lower edge appears to be sticking out slightly, what is the problem most likely to be?
A rolled eyewire
What type of lens will not give evidence of being twisted or rotated in the frame when being checken in a lensometer
spherical lens
If a cellulose acetate fram has been stretched by a previous lens that was ground too large (making the new lenses too small for the frame) what is the best way to remedy the problem?
lheat th frame and plunge it into cold water
A pair of glasses is being verified. One lens is obviosuly in a rotated position, yet the axis of the cylinder for this lens is correct when read on the lensometer. What might be the cause
Lens was edged off axis
what is the easiest way to chck fo a rotated lens after lens inseration when the lenses are flat top multifocals?
use a straight edge and hold it along the top of both multifocal segments. Both seg tops should be parallel to the straight edge.
If a person with a high minus spectacle Rx swithces to contact lenses, the power in the contact lens would be ( ) the power in the spectacle lens??
Less than
If a single vision lens is placed in the lensometer in the reverse position (concave side toward the ovserver) the poewr value obtained is a masure of the ?
front vertex power
The back vertex power is greater than the front vertex power if??
A thick lens has a convex front surface and a plan backs urface
