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Canadian Certified Optometric Assistant > Module 6: Ophthalmic Frames > Flashcards

Module 6: Ophthalmic Frames Flashcards

1
Q
  • holds lenses
  • called eyewire
  • plastic/metal
  • full/semi/ rimless
    -semi=string mount=beleved flat lens
  • combination=plastic top/metal bottom
A

Front

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2
Q

-frame front joins 2 eyewires together
- supports on px nose
- Saddle/keyhole/modified saddle
- saddle= one curve> distribute weight evenly
- modfied saddle= added nosepads
-keyhole= old fashion keyhole>top flares out> rests at side nose= not on the crest
-metal frames = nosepads

A

Bridge

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3
Q
  • attached to “gaurd arms/pad arms”
  • guard arm shapes (horiztonal ?/inverted U) or (American arm gaurd/ European arm guard)
  • attached with screws/snap on/clips (rayband)
  • plastic/silicone/ceraminc/glass/titanium
  • plastic = hard & durable
  • silicone = soft but replaced often (allergy is red/itchy)
  • can have customized guard arms onto plastic frame
A

Nose Pads

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4
Q

-located @ outer edge of frame front
- hinges located here (mounted on or in/connect to temple)
-endpiece and temple have half barrels to connect
- Barrel is where the screw goes to hold peices together
- some frames are continous (no endpiece)
- 3 types
1) Mitre (45 * angle meeting point)
2) Butt (90* angle meeting point)
3)turn-back (frame wraps around to meet temple)

A

Endpieces

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5
Q
  • attach to frame front & wrap around ears
    -butt end = temple location closest to frame front
  • bend= first starts to bend at the ear
    -shank/shaft/length to bend (LTB)= distance between butt end/bend
    -earpiece = part that wraps around ear
    -skull/paddle/spatula= most common, silicone tips (doesn’t wrap ear)
  • Library- wraps skull not ear (take on/off freq)
    -cable= tight wound coil, wraps around whole ear to lobe (children, doesn’t slide)
    -Spring hinge= take impact
A

Temples

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6
Q
  • insertion/mounting/glazing = same thing
A

Lens insertion/removal

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7
Q
  • heat usually used acetate (zyl)
    -Optyl MUST have heat or will SNAP
  • cellulose propionate/polyamide = cold mounting/snapping (squishy thin plastic)
A

Plastic insertion

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8
Q

-clean from debris
-warm up temple (air blower)
-frame facing you> temple edge in first
-both thumbs> push front surface @ naval side
-double check in place around
- can do bridge adjustments while still warm
-rolling= lens rolls over frame> correct eyewire inward

A

Zyl/ Optyl insertion

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9
Q
  • requires heat (optyl more so)
    -wrap lens w/ soft cloth
  • air blower > bridge area
    -thumbs back lens @ bridge> push outwards
    -bead heater= frame parallel to top beads> constant movement (no lens protection)
A

Zyl/Optyl removal

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10
Q
  • same as zyl but no wrapping or heating required
A

Polyamide/polypropionate insertion/removal

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11
Q

-same as zyl but use warm water to heat up

A

Nylon insertion/removal

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12
Q
  • uses screws to loosen eyewire/lens
  • match lower/upper curves
  • use hockey puck/work bench (prevent slipping)
  • consider self-tapping screw (pointed tip/can be shortened)
A

Metal frame insertion/removal

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13
Q

l - lenses mounted directly to bridge/temples
- small holes drilled nasal/temple
-screws/nylon plugs secure lens to frame
- screws earier to replace

A

Drilled rimless insertion/remova

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14
Q
  • nylon cord/semi-rimless
    -check cord properly threaded
  • place lens in top frame first
  • used hook ribbon to control nylon placement
  • start at nasal end> stretch over lens
  • check cord tension
A

String mounted insertion

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15
Q
  • use ribbon> pull string away from lens@ temple
A

String mounted removal

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16
Q
  • older metal frames made of gold
  • combo of alloys (nickle/copper/trace elements)
  • most common
    -wide range of colours
  • corrosion resistant
  • less allergic reactions
  • holds adjustments well
A

Monel metal Frame

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17
Q
  • alloy metal (iron/chromium)
  • mostly childrens frames
  • light weight
    -strong and thinner than Monel
  • cheaper than titanium
    -corrosion resistant
  • hypoallergenic
  • limited colours
    -difficult to solder
  • hard to curve for high case curves
A

Stainless Steel Frame

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18
Q
  • used in pure form or mixed alloy
  • extremely strong/durable
  • very light weight
  • common in rimless frames
  • hypoallergenic
  • corrosion resistant (humid climates)
  • blended with nickel= memory metal
  • expensive
  • limited colours
A

Titanium Metal frames

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19
Q
  • regaining popularity
    -wide variety colours
  • non-corrosive
  • light weight
  • difficult to adjust
  • finish scratches easily
  • cannot solder
    -pad arms/hinges must be riveted
  • repairs difficult
A

Aluminum metal frames

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20
Q
  • revolutionary titanium nickel alloy
    -light weight
  • durable/flexible
  • keep shape after twisting
  • great for children
  • hard to make adjustments
A

Flexon metal frames

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21
Q

-Zyl/ Zylonite
- rolled into sheets/ parts stamped out
- variety of colour/texture
- designs vary due to dye lots changing
-hinges sunken by heat/rivet
-can be tinted
- heated for adjustments
- has metal core to hold shape
- heavier
- tends to fade
- break in cold weather
- milk white coating with age
- overheating = blisters

A

Cellulose acetate plastic frames

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22
Q
  • “propionate”
  • injected into molds
  • thinner plastic
  • malleable feel
  • must be cold mounted
  • lighter than acetate
  • cheaper
  • very sensitive to heat
  • has no material memory
  • lens inserted room temp
  • acetone/alcohol= discolouration
A

Cellulose Propionate plastic frame

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23
Q
  • nylon blend
  • injected into molds
  • thinner/malleable
    -cold mounting lenses
  • heat = shrinks eyewire
  • light weight
  • flexible
  • strong/scratch resistant
  • colours don’t fade
A

Polyamide plastic frames

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24
Q
  • trademarked material
    -epoxy resin
  • has memory
  • bent any shape with heat>cooled
    -re-heated returns to original shape
    -high luster
  • will break/snap without heat first
  • never opaque
    -hypoallergenic
    -wide range colours
A

Optyl plastic frames

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25
Q
  • sports/safety/sunglasses
  • durable
  • not flexible
  • solid colours only/limited
  • light weight
  • hypoallergenic
    -impact resistant
  • adjusting/mounting difficult
  • brittle when dehydrated
  • soak in water monthly
A

Nylon plastic frame

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26
Q
  • protective shields/sport/safety
  • same material as lenses
    -impact resistant
  • lenses can be moulded into frame (one unit)
    -virtually unbreakable
    -limited colours
  • difficult to adjust
  • avoid acetone
A

Polycarbonate plastic frames

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27
Q
  • “graphite”
  • alternative to metal frames
  • nylon mixed strands carbon fiber
    -light weight
  • thinner than acetate
  • always opqaue
  • limited colours
  • can snap adjustments in cold
  • difficult to adjust
  • not great for high base curve lens
  • eyewire close with screws
A

Carbon Fiber plastic frames

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28
Q
  • unfreezing
  • use oil/heat/ ultrasonic cleaner
  • loctite= loosen with heat
A

Remove stuck screws

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29
Q
  • extractor/slotting file/punching/drilling)
    -grasp with plier> twist out threads
  • use long screw &nut OR self-tapping screw
A

Remove broken screw

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30
Q
  • barrels spread apart
  • remove screws first
  • use double nylon plier/needle nose plier
    -press bottom/top hinge together
  • space with paper clip/ cardboard
A

Tighten loose hinge

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31
Q
  • use quality cutter
  • ant clean edges (risk of injury to fingers)
  • flat rasp/thumb file to soften edges
  • cover exposed frame areas prevent damage
A

Cut/File long screws

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32
Q

-peening/nail polish/ adhesive sealant
- not common
- use loctite ( not in hinges)
- peening =plier (splays) screw across opening
- clavulis press can help

A

Secure screws

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33
Q
  • temple hinge= key factor
  • same barrel size/ # of barrels
A

Replace temples

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34
Q
  • notice mounting type/size/material
  • changing style/size = frame adjustments
A

Replace nose pads

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35
Q
  • match colour/length
  • cut off old with pliers/ heat & slide
  • straighten bend first= easier
A

Replace plastic earpiece covers

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36
Q
  • cutting/filing
  • thinner metal temples ideally
A

Shorten long temple

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37
Q

-some plastic frames can shrink with heat
- metal frames = lens liner (1/4 eye size)> into bevel

A

Loose lens in eyewire

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38
Q
  • not all metals can be soldered
  • short-term fix
A

Solder broken metal frame

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39
Q
  • remove broken cord
  • cut diagonal end new string
  • string thru nasal end first> clamp> push thru lower hole
  • check cord length> string into lower temple> insert lens> pull tight> mark/dent placement
    -remove lens
  • re-string cord into TOP temple hole
  • use ribbon to control cord
  • insert lens
  • clip off extra cord leaving 3mm
A

Broken nylon cord

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40
Q
  • replace screws and bolts
  • might need washers prevent lens damage
  • nylon plugs = correct pliers
    -use tape to protect lens
    -clip backside of plug/ take out
  • move tape to front holes> puncture w/pin
  • insert new at back first
    -pressing backside> green handle trimmer> cut plug flush front lens
    -push pin to open the cut end tubes> enlarge/flare w/ pin circular motion
    -remove tape
    -insert metal mount> gently rocking
  • blue tip gripping pleir> gently close plier
A

Repair rimless

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41
Q
  • heat pan/ salt pan/ glass beads/ air blower
  • rotate for even heating
  • salt = hotter than air blower
  • stir salt with wooden spoon
  • wrap in cloth prevent damage
A

Heating equipment

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42
Q
  • remove lenses before ultrasonic cleaners
  • ultrasonic cleaner 1-2 mins
  • soft toothbrush> mild soap
  • palstic not ideal for ultrasonic (soap/water)
A

Cleaning equipment

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43
Q
  • Bench alignment= aligned before adjusting frame
  • benching when back from lab
  • make sure all screws are tigth
  • bridge> eyewire>endpieces>temples
A

Standard Alignment

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44
Q

-horizontal alignment= endpeice/eyewire/bridge are level

A

Bridge alignment

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45
Q

-one lens tilts out/ other tilts in (one lens closer to cheek)
- view bridge from side
- not parallel

A

X-ing

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46
Q

-view from the front
- one lens higher off the table (bridge bent)

A

Skewing

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47
Q
  • view bridge from top
  • one lens more forward than the other towards the eye/face
A

Coplanar adjustment

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48
Q
  • suppose to follow curves of skull/head
  • too much face form = distortion
  • adjust is px PD is less than frame PD
A

Face form

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49
Q
  • should be 90* parallel to eyewire/hinge
A

Temples

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50
Q
  • angle of bottom lens
  • usually 8-10* inward> toward cheeks> further from eyes
  • both side should match
A

Pantoscopic tilt

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51
Q
  • angle of bottom AWAY from cheeks> top closer to eyes
A

Retroscopic tilt

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52
Q
  • no tilt/ straight verticle downwards
    -2* of tilt changes OC by 1 mm
A

Orthoscopic tilt

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53
Q
  • should be 45*
  • same distance from hinge each side
A

Earpeices

54
Q
  • temples should cross at center bridge
  • keep closed while adjusting
  • use temple-angling/finger-peice (parallel jaws)
A

Temple fold

55
Q

-use nosepad pliers/snipe nosed pliers/needle nose pliers/square-round pliers
-Frontal angle (tops closer/ bottoms further apart)
-Splay angle ( inside edge closer than outside)
-Verticle angle (bottom tip closer to eyewire/ top further from eyewire)

A

Nose pads

56
Q
  • only touching the px nose/ side of head/ ears
A

Fitting triangle

57
Q
  • check if bend is located infront of ear
  • dissappear behind ear> no visible curve
A

1 Temple bend

58
Q
  • only touching slightly @ top of ear
  • too much pressure= frames moving forward
  • too little pressure= lacks stability
  • unequal pressure = vertex distance error
  • lens IN-temple IN/ lens OUT- temple OUT
  • adjustments at butt ends/endpeices
A

2 Temple spread

59
Q
  • OD too high? raise OD hinge upwards
  • OS too low? bend OS hinge downwards
  • watch panto tilt/ cheek touching
  • even with uneven ears
A

3 Level Front front should look horizontally level

60
Q
  • sitting too low/high on nose (OC decentered)
  • use bridge-widening/ narrowing pliers
  • change nose pad distance
  • watch vertex distance (needle nose pliers)
A

4 Frame height

61
Q
  • full surface nose pad touching the nose
  • uneven contact = marks/soreness
  • sit halfway between crest & inner canthus
  • too big if pressing into inner canthus
    -silicone pads sticky OR soft (depends on px)
A

5 nose pad angles

62
Q
  • 2 bends
    1) behind root of ear (ear joins head)
  • too far forward = temple lift up
    2) inward curve match skull shape
A

6 temple/earpiece

63
Q
  • pull frame forward> check equal tightness
    -lift the frame up & drop back down
  • ask if feeling too tight/loose
  • dont place on top of head when not using
A

7 Final check

64
Q

1)appropiate for lens Rx (consider lens weight & thickness)
2)fit px facial structure (face shape/skin tone)
3)perform for intended use (computer/sports)
4)should look attractive
- dont make assumptions about px budget
- ask open-ended questions
- listen (dont interrupt px)
- offer high qaulity/ attractive FIRST (px often buy first frame tried on)
- px concerned cost> offer mid-range next
- discuss durability
-avoid letting px browse alone> maintaine control
- don’t show more than 2-3 frames at a time
- square face = rounded edges
- wide jaw = high temples
-high bridge = saddle style (shorter illusion)
- green skin undertone= avoid yellow/green/blue
- explain WHY features of frame style
- give technical reason for disagreements

A

Frame selection

65
Q
  • offer to return with friend/family
  • seek opinions of coworkers
  • send the px home with 2 styles
  • take a photo
  • suggest returning another day (refreshed)
  • encourage looking through fashion mags
A

Indecisive px

66
Q

-also working with parent
-adress child/important opinion too
-frames flatter than adults
-wider bridges
- shorter temples
- fit around ears with high rx (balance weight)
-child must like or won’t wear

A

Children

67
Q
  • dark frame =draw attention features
  • light frame = minimize facial features
  • explain WHY its complimentary
    -Square = rounded edges (softer angles)
    -Oval = anything
  • Triange = oval/midheight temple
    -inverted triangle = higher temples
  • Round = squared edges/ higher temples (create angles)
    -Diamond= shallow ovals/geometrics/rectangles/
    high temples
  • Rectangle= round/square/ mid height temple (soften)
A

Face Shape

68
Q
  • shaft/shank should not press into the side of head
  • should not see any gaps side of head
  • major critia of frame fit
  • wide front hindge helps narrow PD
    -spring hinge can accidentally look good fit
A

Head Width

69
Q
  • most important fit features
  • no gaps/ no slips (px wrinkle nose)
A

Bridge of nose

70
Q

-must match to saddle or contoured bridge
-comfortable
-bad fit = red marks on crest
-try keyhole

A

Crest Angle

71
Q

-ideal fit (top bridge & frontal) no gaps
- poor fit = red marks/discomfort

A

Frontal Angle

72
Q
  • nose to face
  • cant adjust saddle/keyhole
  • nose pads with pliers
A

Splay Angle

73
Q
  • can change pantoscpoic angle
  • compare ear height to eye position
  • try higher/ lower temple placement styles
  • low ears = mid-height/low temple (avoids retroscopic angle)
  • high ears= higher temple (avoid resting on cheeks)
A

Ear Height

74
Q

-minumum of 35mm required
-too long = discomfort/end seen below lobes
- too short=no length to bend/ will slip off
- measure length to bend (LTB)
- extra front hinge= fit longer

A

Temple length

75
Q

-consider skin tone/hair colour/ eye colour
- colour should enhance skin colour
- right colour avoids under eye shading
- warm =camel/gold/peach/orange/warm blue
-cool=black/silver/pink/jade/plum
-skintones= pink/red/orange/blue/yellow
-under eye shading= clear/shallow bottom half
- frame colour should make face brighter

A

Px skin tone

76
Q

Px own frame

A
  • check durability
77
Q
  • choose smaller frame
  • match px PD with frame PD (eye size&bridge)
  • full frame
    -longer front hinge
    -thicker frame hides more lens
  • nose pads help fit
    -high index with AR
  • request lab move bevel back
  • compare vertex with phoropter
A

High Minus/Plus Rx

78
Q

-2.00 and above
- less round (avoid axis shifting)
-bridge fit = less frame rocking/axis
- eyewire hide changes in lens thickness

A

High cylinder Rx

79
Q

= evenly touch only 1mm movement
- lower bridge = shorter looking nose (saddle)
- keyhole= longer looking nose

A

Noses -fixed bridges

80
Q
  • minimal vertex distance (close= wider reading)
  • needs more panto(reading area closer to eye)
    -verticle dimension lens allow min fitting height plus 15mm
  • avoid large frames in high Rx
  • avoid aviators
A

PAL

81
Q
  • frame matieral important
    -spring hinges useful
  • cushioned nose pads for impact
  • must comply with Canadian Standards Assoc.
A

Sports/Safety

82
Q

-noses still growing (short and flat)
- skin more senstive
- deeper than normal eyewire groove (lens secure)

A

Children

83
Q
  • skin is thin/tender/slow to heal
  • nose and behind ears more irritated
  • nose pads as large as possible
  • easy to put on and off (arthritis)
A

Elderly

84
Q
  • drawn box of outside lens edges
    -accurately measures lens size (A)
  • does not measure frame size
    -also measures Distance between lenses (DBL)
  • important for lens frabrication when sending order to lab without frames present
  • allows seg. & pupil height to lowest part on lens
A

Boxing System

85
Q

the measurement of the lens horizontally at the widest point (A)

A

The lens size

86
Q

The measurement of the lens vertically at the deepest point of lens (B)

A

The lens height

87
Q

The horizontal line 1/2 way bewtween top and bottom lens edges

A

Datum Line

88
Q

The difference between (A) and (B) measurements

A

Frame difference

89
Q

where the lens bevels are closest to another

A

Distance between lenses (DBL)

90
Q

-The exact centre of the lens
- not related to OC

A

Geocentre (GC)

91
Q

-Distance between geocentres
- calculated as (A) + (DBL)

A

Frame PD

92
Q
  • helps decide smallest blank size
  • 2x the distance of geocentre to furthest lens edge
    (the longest radius from the geocentre)
A

Effective Diameter (ED)

93
Q
  • has several meanings
  • sometimes = DBL
    -somtimes = width of datum line
  • sometimes= circumference of lens
  • WATCH OUT
A

(C) measurement

94
Q
  • 3 measurements
    1) eye size
    2) bridge size
    3) temple length
A

Frame markings

95
Q
  • First # marked on frames
A

Eye size

96
Q
  • Second # marked on frames
A

Bridge size

97
Q
  • printed/located on the bridge
  • has a box symbol between both #
A

Accurate (A) + (DBL)

98
Q
  • printed/located on the temple
  • dash between both #
  • smaller eye size = shorter temple length
    -frame might come in various size options
A

Inaccurate frame measurements (dont use for lab)

99
Q
  • # usually on the temple
  • 3rd frame measurement
A

Frame Temple length

100
Q

-not recorded on frames
- measure with PD ruler
- front temple hinge > bend of temple

A

Length to bend

101
Q
  • 2mm increments
  • adult 48mm-64mm
A

eye size (A) options

102
Q

-14mm-24mm

A

bridge size (B) options

103
Q
  • 5mm increments
  • 110mm-130mm children
    -120mm-150mm adults
A

Temple size options

104
Q

-measures distance between pupils (mm)
- abbrv. PD
-OC infront of visual axes thru pupils
- several techniques available
- distance = numerator
-near =denominator

A

Interpupillary Distance

105
Q

-used in equipment failure
- home visits
- crooked/uneven noses

A

Corneal reflection pupillometer

106
Q

When px is focused on a distance target

A

Distance PD

107
Q

-Narrower measurement
- eyes converging
-near targets @ 40cm

A

Near PD

108
Q

The distance between two pupils

A

Binocular PD

109
Q

The distance from each pupil> nose center

A

Monocular PD

110
Q
  • 40 cm infront of px
  • eye level
    -hold ruler horizontal on px bridge
  • rest hand on cheek/forehead
    -px look at your open eye
    -OS open> line up 0mm> px OD pupil
A

Binocular distance PD with ruler

111
Q
  • use penlight @ below px eye> point of reflection in each pupil
    -outside edge OD pupil> inside edge OS
A

Uncommon Binocular distance PD

112
Q

-you use better eye infront of px @ px nose
-px focus on open eye (@ nose)
-px OD pupil center > OS pupil center

A

uncommon Binocular near PD

113
Q
  • use regular binocular set up with ruler
  • note the (mm) at the center of px nose= OD
  • subtract OD(mm) from binocular # = OS
A

Monocular PD with ruler

114
Q
  • most accurate PD measurement
  • hold device level
  • allign vertical black line with px pupil
  • set at infinity oo = distance
  • intermediate= 55-75mm
  • near = 40mm
A

Pupillometer Binocular

115
Q

-use occuler
- best for px muscle issues
- px with strabismus

A

Pupillometer Monocular

116
Q
  • staff larger or narrower PD than px w/ ruler
  • not at the same height at px
  • px moves head
  • inaccurate directions to px
A

PD errors

117
Q
  • measure outer canthus OD> inner canthus OS
    -outer limbus OD cornea> inner limbus OS
    -px wear frame>dot pupil center> measure distance
    -Children/ parkinsons/cerebral palsy
A

ruler PD with special needs

118
Q

-amount of near OC lens (mm) to distance OC
-near PD always smaller than distance PD
-distance PD (-) near PD = inset (binocular)

A

Segment Inset (PAL/Bifocal)

119
Q
  • amount of angle deviates from vertical
    -bottom eyewire close to face
    -critical from eyes distance to OC on lens
A

Pantoscopic Tilt

120
Q

-location prism or OC
- height is important
-more than 5mm above (+)/below(-) datum line = lens too thick at edges (unappealing cosmeticall)
-not telling lab vertical measurement= lab uses datum line
- horizontally = px PD

A

Major Reference Point (MRP)

121
Q

1) adjust frame to px
2) be at eye level to px
3) px looks at your nose
4) raise px chin= frame perpendicular to floor
5) draw horizontal line at pupil
6) measure distance from line to bottom lens
!!! missing step 2 =calc. drop of MRP based on *of panto tilt!!!

A

How to measure MRP

122
Q
  • MRP places 1mm below pupil for every 2* of pantoscopic tilt
    (8* panto = MRP 4mm below pupil)
  • automated tech for Freeform does for you
A

Natural line of sight

123
Q

-distance between lens and px cornea
- use px rx phoropter (12-14mm)
- high rx (7.00 -/+) = changed power with too close/too far from cornea
-measureed with distometer

A

Vertex Distance

124
Q

-px closes eyes
-pre-adjusted frame
-at frame/face side rest flat tip @ eyelid
-press button until reaches back of lens
-read scale
-compare refracted vs frame vertex
-difference of 1-2mm can shift rx
- Freeform tech does this for you
- No vertex reconding lab uses default 12/13mm

A

Meausreing Vertex

125
Q

-Curve of the front of the frame
-ideally curve follows px head shape
- too much/too little curve = optical issues
-Freeform requires measurement

A

Face form (wrap)

126
Q

-use chart
-place frame OD eyewire flat @ dotted line
-line up OS and note * of angle

A

How to measure Face Form

127
Q

-location at which multifocal power> facial structure> shape of frame
- must use extact frame size
- (+)/(-) 1mm for every 2mm of frame size required
- frame size 54mm wants (sample is 52mm) = adding 1mm vertical height

A

Segment Height (seg height)

128
Q
  • be at px eye level
  • not eye level = parallax (skews mesurements)
  • px be in normal/comfortable position
    -focus straight ahead
    -px look at your oppostie eye/nose
    1) 0mm rule at pupil measure to bottom lens
    2) mark pupil> draw horizontal line
    3) seg devices sit inside bevel (child/ height difference OD/OS
  • check twice (have px relax in between)
    -flattop line @ bottom pupil
    -round bifocal @ bottom pupil (+) 1mm
    -PAL line @ center pupil
    -flattop trifocal @ bottom pupil (-) 1mm
  • add 0.5mm to compensate frame groove
A

How to measure Seg Height

129
Q
  • tall px= seg height lower than normal
  • neck conditions(chin down)= higher height
  • uneven height is ok
  • show px line on bifocal/trifocal
  • can balance out if less than 3mm diff OS/OD
A

Troubleshooting Seg Heights

130
Q
  • center pupil marked (fitting cross location)
  • MRP usually 2-4mm below fitting cross
  • use centration charts
A

PALSeg. Heights

131
Q
  • must be using lower portion for near work
    -reading area must be placed higher
  • flat top = measure @ center pupil
  • PAL = center pupil (+) 4mm
A

Childrens seg height

132
Q

-lenses before cut/shaped to frame
-the smallest lens size that will fit
-keeps lens edges thinner
- reduces lens weight
-SV can be kept at stock (pre-made)
- MF seg determines MBS large enough (using scale chart)

A

Minimum Blank Size (MBS)

Canadian Certified Optometric Assistant (9 decks)

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