Ophthalmic Optics
25%of exam
Ocular Anatomy and Refraction
10%of exam
Ophthalmic Products
20%of exam
Instrumentation
15%of exam
Dispensing Procedures
20%of exam
Laws, Regulations and Standards
10%of exam
Quick Facts
- Exam
- NOCE (ABO Basic)
- Credential
- ABO Certified Optician
- Items
- 125 delivered, 100 blueprint
- Time
- 2 hours
- Pass
- Criterion-referenced, cut unpublished
- Fee
- $225 (NOCOP $250)
- Delivery
- Prometric or ProProctor
- Retake
- 14 days, three attempts
- Renewal
- Every 3 years
- Blueprint
- Feb 2025 handbook
Transposition Steps
Add, flip, rotate ninety
Add cyl to sphereFlip the cylinder signRotate axis 90 degTotal power unchanged
Minus vs Plus Cylinder
Minus cylinder
- Cylinder written negative
- Sphere is most plus
- Lab and optometry standard
Plus cylinder
- Cylinder written positive
- Sphere is most minus
- Common on medical Rx
Same lens, two notations
Anisometropia Picker
- Imbalance below threshold→No prism correction(Recheck symptoms)
- Vertical imbalance at near→Slab-off prism(Bicentric grinding)
- Choosing the slab lens→Most minus or least plus(Adds base up)
- Prefers a molded lens→Reverse slab-off(Base down, more plus)
- Wants a simple fix→Separate single vision readers(Set lower OCs)
- Small imbalance only→Lower both optical centers(Reduces induced prism)
Prescription Notation
- OD
- Right eye, oculus dexter
- OS
- Left eye, oculus sinister
- OU
- Both eyes together
- Sphere
- Power in every meridian
- Cylinder
- Extra power one meridian
- Axis
- Meridian without cylinder power
- Add
- Extra plus for near
- PD
- Pupillary distance in millimeters
- Plano
- Zero sphere power
- DV, NV
- Distance vision, near vision
- BI, BO
- Base in, base out
- BU, BD
- Base up, base down
- Balance lens
- Cosmetic match, no correction
Prentice's Rule
Prism equals centimeters times diopters
Decentration in centimetersPower in diopters10 mm equals 1 cm5 mm, 2 D, 1 prism
Vertex Move: Plus vs Minus
Plus lens closer
- Effective power weakens
- Order more plus
- Matters above 4.00 D
Minus lens closer
- Effective power strengthens
- Order less minus
- Matters above 4.00 D
Closer needs more plus
Core Optical Formulas
- Prentice's rule
- Prism = decentration cm x F
- Spherical equivalent
- Sphere + half the cylinder
- Transposition
- Add cyl, flip sign, rotate
- Oblique meridian
- S + C times sin^2 theta
- Nominal lens power
- F = F1 + F2
- Surface power
- (n2 - n1) / radius m
- Sagitta
- h^2 x F / 2000(n-1)
- Vertex compensation
- F / (1 - dF)
- Minimum blank size
- ED + 2 decentration + 2
- Decentration per lens
- (frame PD - PD) / 2
- Frame PD
- A + DBL
- Near PD
- Distance PD minus 3-4 mm
- Add power
- Near minus distance power
- Accommodation needed
- 1 / working distance meters
Prism Base Direction
Plus toward center, minus toward edge
Plus below OC: base upMinus below OC: base downBase sits at thick edge
Slab-Off vs Reverse Slab
Conventional slab-off
- Ground bicentrically
- On more minus lens
- Adds base up
Reverse slab-off
- Molded into the blank
- On more plus lens
- Adds base down
Opposite lens, same result
Prism and Imbalance
- Prism diopter
- 1 cm shift at 1 m
- Plus lens prism
- Base toward the optical center
- Minus lens prism
- Base away from optical center
- Below OC, minus
- Induces base-down prism
- Below OC, plus
- Induces base-up prism
- Horizontal prism
- Same base adds, opposite subtracts
- Vertical prism
- Opposite bases add, same subtracts
- Splitting prism
- Half each eye, opposite bases
- Vertical imbalance
- Vertical prism difference at near
- Symptomatic imbalance
- Roughly 1.5 prism D difference
- Slab-off lens
- Most minus or least plus
- Slab-off prism
- Base up in reading zone
- Reverse slab-off
- Base down on more plus
Vertex Move Rule
Closer: more plus, less minus
Farther: less plusFarther: more minusCompensate above 4.00 D
Vertex and Effective Power
- Vertex distance
- Cornea to lens back surface
- Typical vertex
- About 12 to 14 mm
- Compensate above
- Powers over 4.00 D
- Plus moved closer
- Order more plus power
- Plus moved farther
- Order less plus power
- Minus moved closer
- Order less minus power
- Minus moved farther
- Order more minus power
- Effective power
- Power at the corneal plane
- Compensated power
- Power ordered for new vertex
- Measuring tool
- Distometer against closed lid
Phoria vs Tropia
Phoria
- Latent deviation
- Fusion keeps it aligned
- Shown by cover test
Tropia
- Manifest deviation
- Visible with both open
- Constant or intermittent
Hidden versus visible turn
Ocular Anatomy
- Cornea
- Most of eye's refraction
- Aqueous humor
- Fluid in anterior chamber
- Iris
- Controls pupil diameter
- Crystalline lens
- Changes shape to accommodate
- Ciliary body
- Accommodation and aqueous production
- Vitreous humor
- Gel in posterior segment
- Retina
- Rod and cone layer
- Rods
- Dim light and periphery
- Cones
- Color and fine detail
- Fovea
- Sharpest central vision point
- Optic nerve
- Carries signal to brain
- Optic disc
- Blind spot, no receptors
- Sclera
- Tough white outer coat
- Extraocular muscles
- Six move each eye
Refraction and Pathology
- Myopia
- Focus in front of retina
- Hyperopia
- Focus behind the retina
- Astigmatism
- Two different focal meridians
- Presbyopia
- Age-related accommodation loss
- Anisometropia
- Unequal power between eyes
- Aniseikonia
- Unequal retinal image size
- Amblyopia
- Reduced acuity, healthy structure
- Glaucoma
- Often raised intraocular pressure
- Cataract
- Clouded crystalline lens
- Macular degeneration
- Central vision loss
- Scotoma
- Blind area within field
- Aphakia
- Crystalline lens absent
- Pseudophakia
- Intraocular lens implanted
- Nystagmus
- Involuntary rhythmic eye movement
- Strabismus
- Misaligned visual axes
- Diplopia
- Double vision
Accommodation and Acuity
- Accommodation
- Plus power the eye adds
- Amplitude
- Maximum accommodation in diopters
- Near point
- Closest clear focus distance
- Far point
- Farthest clear focus distance
- Range of vision
- Near point to far point
- Snellen 20/20
- Normal distance visual acuity
- Snellen 20/40
- Reads 40-foot line at 20
- Legal blindness
- 20/200 corrected or 20-degree field
- Cover test
- Reveals phoria or tropia
- Convergence
- Eyes turn inward together
Boxing System Letters
A width, B height, DBL bridge
Frame PD = A + DBLED is longest diameterGC is box center
Polycarbonate vs Trivex
Polycarbonate
- Index 1.586, thinner
- Abbe 30, more fringe
- Lower cost
Trivex
- Index 1.53, thicker
- Abbe 43-45, clearer
- Lightest at 1.11
Thinner versus clearer
Lens Material Picker
- Child or sports wear→Polycarbonate(Impact first)
- Job needs Z87 rating→Polycarbonate or Trivex(High impact)
- Rimless drill mount→Trivex(Resists cracking)
- Low Rx, best optics→CR-39(Abbe 58)
- Rx above 4.00 D→1.60 or 1.67 index(Thinner edges)
- Rx above 8.00 D→1.74 index(Thinnest option)
- Wants lightest lenses→Trivex(Gravity 1.11)
- Color fringe complaint→Raise the Abbe value(Lower index)
- Needs top scratch resistance→Crown glass(Heavy and brittle)
Lens Materials
- CR-39
- Index 1.498, Abbe 58
- Crown glass
- Index 1.523, Abbe 59
- Trivex
- Index 1.53, Abbe 43-45
- Polycarbonate
- Index 1.586, Abbe 30
- Mid index 1.60
- Abbe near 36 to 42
- High index 1.67
- Abbe near 32
- Ultra high 1.74
- Abbe near 32
- Lightest material
- Trivex, gravity 1.11
- Heaviest common
- Crown glass, gravity 2.54
- Best plastic clarity
- CR-39, highest Abbe
- Inherent UV block
- Polycarbonate and Trivex
- Higher index means
- Flatter curves, thinner lens
- Lower Abbe means
- More color fringe peripherally
Minimum Blank Size
ED plus twice decentration plus two
ED from frame shapeDecentration per lens2 mm chipping allowance
Bifocal vs Progressive
Flat-top bifocal
- Visible segment line
- Wide stable near
- No intermediate power
Progressive
- No visible line
- Intermediate corridor
- Soft peripheral blur
Field width versus seamless
Multifocal Picker
- Wants no visible line→Progressive(Blended corridor)
- Shallow B measurement→Short corridor progressive(Check minimum height)
- Needs wide near field→Flat-top 28 bifocal(Stable near)
- Needs the widest near→Executive bifocal(Full width ledge)
- Computer plus reading→Trifocal or office lens(Intermediate zone)
- Progressive nonadapt→Flat-top bifocal(Accepts the line)
- First presbyopic add→Progressive, low add(Easier adaptation)
Lens Designs
- Single vision
- One power throughout lens
- Flat-top 28
- Flat segment, 28 mm wide
- Round segment
- Curved top, older style
- Executive
- Ledge across full width
- Trifocal
- Distance, intermediate and near
- Progressive
- Blended corridor, no line
- Short corridor PAL
- Fits shallow B measurement
- Aspheric
- Flatter, thinner, less magnification
- Lenticular
- Central bowl, thin carrier
- Blended bifocal
- No line, blurred junction
- Freeform
- Digitally surfaced point by point
- Base curve
- Front curve of lens
Coatings and Tints
- AR coating
- Cuts reflections, raises transmission
- Surface reflection
- About 4% per uncoated surface
- Scratch coat
- Hard layer, not scratchproof
- Hydrophobic layer
- Sheds water and smudges
- UV treatment
- Blocks up to 400 nm
- Photochromic
- UV darkens, heat weakens
- Windshield problem
- Glass blocks activating UV
- Polarized
- Blocks horizontal reflected glare
- Mirror coating
- Reflects light off front
- Gradient tint
- Dark top, clear bottom
- Tint density
- Percent of light absorbed
- UV-A range
- 315 to 400 nm
- UV-B range
- 280 to 315 nm
- HEV blue light
- About 380 to 500 nm
Frame and Boxing System
- A measurement
- Horizontal box lens width
- B measurement
- Vertical box lens height
- DBL
- Distance between the lenses
- ED
- Twice longest geometric center radius
- Frame PD
- A plus DBL
- Geometric center
- Center of the box
- Datum line
- Horizontal midline of box
- Temple length
- Commonly 135 to 150 mm
- Frame marking
- 52-18-140 is eye-bridge-temple
- Eyewire
- Rim that holds lens
- Zyl
- Cellulose acetate, heat adjusted
- Monel
- Nickel alloy, most common
- Titanium
- Light, strong, hypoallergenic
- Bridge types
- Saddle, keyhole, adjustable pads
Lens Clock vs Lensmeter
Lens clock
- Reads one surface
- Calibrated at 1.53
- Needs index correction
Lensmeter
- Reads back vertex power
- Any lens material
- Gives axis and prism
Surface versus total power
Verification Tool Picker
- Check sphere and axis→Lensmeter(Back vertex)
- Check add power→Lensmeter, lens flipped(Front vertex)
- Check base curve→Lens clock(Correct for index)
- Check center thickness→Calipers(At reference point)
- Check vertex distance→Distometer(Corneal apex)
- Check pupillary distance→Pupilometer(Corneal reflex)
- Check segment height→Millimeter ruler(From lower rim)
- Check eyewire length→Circumference gauge(Groove length)
Instruments and Uses
- Lensmeter
- Back vertex power and axis
- Focimeter
- Another name for lensmeter
- Lens clock
- Surface curve, calibrated 1.53
- Distometer
- Vertex distance to cornea
- Pupilometer
- Corneal reflex pupillary distance
- Calipers
- Lens or frame thickness
- Millimeter ruler
- PD, seg height, frames
- Circumference gauge
- Eyewire groove length
- Lens marker
- Dots optical center, axis
- Frame warmer
- Softens zyl before bending
- Angling pliers
- Bend temples and endpieces
- Pad pliers
- Adjust the nosepad arms
- Digital centration system
- Photo based fitting measurements
Lensmeter Technique
- First step
- Focus eyepiece on reticle
- Lens position
- Back surface against stop
- What it reads
- Back vertex power
- Sphere target
- Single lines in focus
- Cylinder target
- Triple lines in focus
- Minus cylinder reading
- Most plus sphere first
- Axis read
- From the drum scale
- Add power
- Flip lens, read front vertex
- Add value
- Near minus distance reading
- Prism read
- Target off the center
- Prism beyond range
- Add an auxiliary prism
- Marking centers
- Dot at target center
- PAL verification
- Use manufacturer circle markings
Seg Height vs Fitting Height
Seg height
- Rim to segment top
- Bifocals and trifocals
- Often at lower lid
Fitting height
- Rim to pupil center
- Progressive lenses
- Design sets the minimum
Segment top versus pupil
Nonadapt Picker
- Blur at distance→Verify sphere, cylinder, axis
- Blur at near only→Check add and seg height
- Floor appears to curve→Compare base curve, tilt
- Eyestrain with doubling→Check PD and prism
- Swim in the periphery→Check PAL fit and tilt
- Color fringes off center→Check Abbe and decentration
- Lashes brush the lenses→Add tilt or vertex
- Frame keeps sliding down→Adjust pads and temple bends
Fitting Measurements
- Monocular PD
- Bridge center to each pupil
- Binocular PD
- Pupil to pupil total
- Near PD
- About 3-4 mm less
- Seg height
- Lower rim to segment top
- Fitting height
- Lower rim to pupil center
- Bifocal placement
- Usually at lower lid margin
- Trifocal placement
- At the lower pupil margin
- Vertex distance
- Cornea to lens back
- Pantoscopic tilt
- Bottom rim closer to face
- Martin's rule
- 1 mm drop per 2 deg
- Face form
- Front wraps around the face
- Measure posture
- Natural head and eye position
- Adjust frame first
- Fit before taking measurements
Adjustment Fixes
- Frame sits low
- Narrow the nosepads
- Frame sits high
- Widen the nosepads
- Frame slides down
- Bend temples behind the ears
- Temples pinch head
- Increase the temple spread
- Bridge pinches nose
- Widen the pad angle
- Lashes touch lenses
- More tilt or vertex
- One side high
- Change that temple's ear bend
- Zyl frames
- Heat before bending
- Metal frames
- Adjust cold with pliers
- Fitting triangle
- Nose plus two ears
- Four-point touch
- Front lies flat, aligned
- Alignment order
- Front, then temples, then pads
- After adjusting
- Reverify PD and seg height
Nonadapt Complaints
- Distance blur
- Verify sphere, cylinder, axis
- Near blur only
- Check add and seg height
- Floor seems curved
- Base curve or tilt changed
- Objects look smaller
- More minus power added
- Objects look larger
- More plus power added
- Eyestrain and doubling
- Check PD and unwanted prism
- Peripheral swim
- PAL fit, base curve, tilt
- Color fringes
- Low Abbe, off-center viewing
- Narrow reading area
- Corridor or fitting height off
- Chin lifted to read
- Progressive fitted too low
- New frame, same Rx
- Check PD, tilt, vertex
- Lenses feel heavy
- Consider Trivex or higher index
- Persistent complaint
- Reverify before remaking lenses
Axis Tolerance Ladder
Fourteen, seven, five, three, two
0.25 D cyl: 14 deg0.50 D cyl: 7 deg0.75 D cyl: 5 deg1.50 D cyl: 3 degAbove 1.50 D: 2 deg
Z80.1 vs Z87.1
ANSI Z80.1
- Dress eyewear accuracy
- Power, prism, fit tolerances
- Not impact protection
ANSI Z87.1
- Occupational eye protection
- Impact tests and markings
- Frame and lens rated
Accuracy versus protection
Z80.1 Power Tolerances
- Sphere to 6.50 D
- Plus or minus 0.13 D
- Sphere over 6.50 D
- Plus or minus 2 percent
- Cylinder to 2.00 D
- Plus or minus 0.13 D
- Cylinder 2.00 to 4.50
- Plus or minus 0.15 D
- Cylinder over 4.50 D
- Plus or minus 4 percent
- Add to 4.00 D
- Plus or minus 0.12 D
- Add over 4.00 D
- Plus or minus 0.18 D
- Cylinder under 0.12 D
- Axis tolerance not defined
- Cylinder to 0.25 D
- Axis plus or minus 14 deg
- Cylinder to 0.50 D
- Axis plus or minus 7 deg
- Cylinder to 0.75 D
- Axis plus or minus 5 deg
- Cylinder to 1.50 D
- Axis plus or minus 3 deg
- Cylinder over 1.50 D
- Axis plus or minus 2 deg
- Progressive sphere to 8.00
- Plus or minus 0.16 D
- Progressive cylinder to 2.00
- Plus or minus 0.16 D
- Progressive cylinder to 3.50
- Plus or minus 0.18 D
Z87 Marking Ladder
Z87 basic, plus is high
Z87-2 marks Rx framesBasic lens 3.0 mmHigh impact 2.0 mm
FDA Ball vs Z87 Ball
FDA 801.410
- 5/8 inch ball
- 50 inch drop
- All dress lenses
Z87.1 basic impact
- 1 inch ball
- 50 inch drop
- Safety eyewear only
Bigger ball means safety
Z80.1 Prism and Fit
- Prism reference point
- 0.33 prism D, or 1.0 mm
- Vertical imbalance
- 0.33 prism D mounted
- Vertical over 3.375 D
- 1.0 mm PRP height difference
- Horizontal imbalance
- 0.67 prism D mounted
- Horizontal over 2.75 D
- 2.5 mm from specified PD
- Segment height
- Plus or minus 1.0 mm
- Segment height pair
- Difference within 1.0 mm
- Fitting cross height
- Plus or minus 1.0 mm
- Fitting cross horizontal
- Within 1.0 mm monocular PD
- Multifocal segment inset
- Within 2.5 mm near PD
- Segment tilt
- Within 2 deg of 180
- Base curve, if specified
- Plus or minus 0.75 D
- Center thickness
- Plus or minus 0.3 mm
- Localized error exempt
- Beyond a 30 mm circle
ANSI Z87.1 Safety
- Z87 marking
- Basic impact rated
- Z87+ marking
- High impact rated
- Z87-2 frame
- Prescription safety frame
- Basic lens thickness
- 3.0 mm minimum
- Thickness exception
- 2.5 mm if +3.00 D
- High impact thickness
- 2.0 mm, no exception
- Basic drop ball
- 1 inch ball, 50 inches
- High mass test
- 500 g pointed, 50 inches
- High velocity spectacles
- Quarter inch ball, 150 ft/s
- Goggle velocity
- 250 feet per second
- Face shield velocity
- 300 feet per second
- Assembly rating
- Lowest rated part governs
- D3, D4, D5
- Splash, dust, fine dust
- V marking
- Photochromic lens
- Usual safety lenses
- Polycarbonate and Trivex
FDA and FTC Rules
- 21 CFR 801.410
- Impact resistant eyeglass lenses
- FDA drop ball
- 5/8 inch ball, 50 inches
- Ball weight
- About 0.56 ounce
- Glass Rx lenses
- Each lens individually tested
- Plastic Rx lenses
- Statistical sample per batch
- Exempt from testing
- Slab-off, lenticular, prism segment
- Exempt lenses still
- Must be impact resistant
- Records kept
- Three years, open to FDA
- Contact lenses
- Not covered by 801.410
- Prescriber may override
- Written finding and notice
- FTC Eyeglass Rule
- 16 CFR Part 456
- Rx release
- Immediately after refractive exam
- Release conditions
- No fee, no purchase required
- Digital Rx copy
- Needs verifiable affirmative consent
- Contact Lens Rule
- 16 CFR Part 315
- Passive verification
- Eight business hours to respond
Standard Editions
- ABO blueprint source
- February 2025 candidate handbook
- NOCE blueprint
- 100 questions, six domains
- Z80.1 current
- Z80.1-2025 supersedes 2020
- Z80.1 change
- Tolerance table fully revised
- Z87.1 current
- ANSI/ISEA Z87.1-2025
- OSHA accepts
- Z87.1 2010, 2003, 1989
- Practice analysis
- ABO-NCLE conducted 2019
- Exam refresh cycle
- About every three years
- Tolerance figures listed
- Z80.1-2015 quick reference values
- Prescribed prism, 2025
- New tolerances added
Common Traps
Blueprint count vs delivered items
Blueprint counts 100 questions ≠ Form delivers 125 items
Z80.1 vs Z87.1
Z80.1 checks accuracy ≠ Z87.1 checks impact
FDA ball vs Z87 ball
FDA drops 5/8 inch ≠ Z87 drops 1 inch
Effective vs compensated power
Effective is at cornea ≠ Compensated is ordered power
Seg height vs fitting height
Seg height to segment top ≠ Fitting height to pupil
Index vs Abbe value
Index sets thickness ≠ Abbe sets color fringe
Which lens gets slab-off
Conventional on more minus ≠ Reverse on more plus
Lens clock reading
Clock assumes index 1.53 ≠ Other materials need correction
Frame PD vs patient PD
Frame PD is A plus DBL ≠ Patient PD is anatomic
Prescription release rule
Given free and immediately ≠ No purchase can be required
Phoria vs tropia
Phoria is latent ≠ Tropia is manifest
Last Minute
- 1.Optics 25%, Products 20%, Dispensing 20%
- 2.Instruments 15%, Anatomy 10%, Laws 10%
- 3.125 items shown, 100 blueprint
- 4.2 hours, on-screen calculator allowed
- 5.Prentice: prism equals cm times D
- 6.Transpose: add, flip, rotate 90
- 7.Vertex closer means more plus
- 8.Sphere tolerance 0.13 D, then 2%
- 9.Add tolerance 0.12 D
- 10.Axis tolerance tightens as cylinder grows
- 11.Seg and fitting height 1.0 mm
- 12.Z87 basic lens 3.0 mm
- 13.Z87 high impact 2.0 mm
- 14.FDA drop ball 5/8 inch
- 15.Poly Abbe 30, CR-39 Abbe 58
- 16.Trivex is the lightest material
- 17.Slab-off goes on more minus
- 18.Frame PD equals A plus DBL
- 19.Martin: 1 mm per 2 deg
- 20.Eyeglass Rx released free, immediately
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