Are flashcards effective for the ABO exam?

Yes. Flashcards use active recall — retrieving an answer from memory — which research shows is one of the most effective ways to make information stick, especially in short sessions spread over several days. That matters for facts like the dioptric power formula, Prentice's rule, lens index and Abbe values, and the boxing-system frame measurements.

What topics do the ABO flashcards cover?

Every ABO content area: Ophthalmic Optics (the largest — lens power, prism, Prentice's rule, transposition, vertex distance), Ophthalmic Products (materials, treatments, multifocal designs), Dispensing Procedures (PD, segment height, the boxing system, pantoscopic tilt), Instrumentation (lensmeter, lens clock, pupillometer), Ocular Anatomy & Refraction, and Laws, Regulations & Standards (ANSI Z80/Z87, FDA, FTC).

Do these flashcards match the current ABO (NOCE) exam?

Yes. Every card is written to the ABO-NCLE Basic exam content outline — Ophthalmic Optics (25%), Ophthalmic Products (20%), Dispensing Procedures (20%), Instrumentation (15%), Ocular Anatomy & Refraction (10%), and Laws, Regulations & Standards (10%) — and to official guidance from ANSI, the FDA, and the FTC, so you study exactly what the exam tests.

How should I study with these flashcards?

Mix the modes: flip to learn, type to test recall, match for speed, and quiz to check yourself. Spend the most time on Ophthalmic Optics — at 25% it is the largest area — and make the dioptric power formula, Prentice's rule, and transposition automatic before moving on.

Are the ABO flashcards free?

Yes — 100% free, all four study modes, no paywall and no sign-up.

What is a diopter (D)?

The unit of lens power — the reciprocal of the focal length in meters. Power (D) = 1 ÷ f (m).

Power (D) = 1 ÷ focal length (meters). A +2.50 D lens focuses at 1 ÷ 2.50 = 0.40 m = 40 cm.

Focal length of a +5.00 D lens?

f = 1 ÷ 5.00 = 0.20 m = 20 cm.

Plus (convex) lens — effect on light?

Converges parallel rays to a real focal point; corrects hyperopia and presbyopia; thicker in the center.

Minus (concave) lens — effect on light?

Diverges parallel rays to a virtual focal point on the incoming side; corrects myopia; thicker at the edge.

What is Prentice's rule?

Prism (Δ) = decentration (cm) × lens power (D). Gives the prism induced by looking away from the optical center.

Prism from looking 5 mm off-center through a 4.00 D lens?

Δ = 0.5 cm × 4.00 D = 2.0 Δ. (Convert 5 mm → 0.5 cm first.)

How is prescribed prism ground into a lens?

By decentering the lens (Prentice's rule) or by a prism-grind, moving the optical center relative to the visual axis.

The prism diopter (Δ): 1 Δ deviates light 1 cm at 1 m (1 cm per meter).

How do prisms at right angles combine?

By vector (Pythagorean) addition: resultant = √(a² + b²). E.g. 3 Δ up + 4 Δ out = √25 = 5 Δ.

Lens transposition — the 3 steps?

1) New sphere = sphere + cylinder. 2) Reverse the cylinder sign. 3) Rotate the axis 90° (keep 1–180).

Transpose +2.00 +1.00 × 090.

→ +3.00 −1.00 × 180 (optically identical, minus-cyl form).

What is the spherical equivalent (SE)?

SE = sphere + (cylinder ÷ 2). For −2.00 −1.00 × 090, SE = −2.50 D.

What is vertex distance?

The distance from the back surface of the lens to the front of the cornea.

Effect of moving a minus lens away from the eye?

It acts stronger (more minus). A plus lens moved away acts weaker.

When is vertex-distance compensation significant?

Around ±4.00 D and stronger; weak prescriptions are negligibly affected.

The front (or reference) surface curvature of a lens, read in diopters with a lens clock; sets the lens's form.

Best-form (corrected-curve) lens — purpose?

A base curve chosen to minimize oblique (marginal) astigmatism for off-axis gaze.

How do you estimate a lens's total power from its surfaces?

Add the front and back surface powers algebraically (with sign).

Effective power vs nominal power?

Effective power is the lens's power experienced at the eye's plane, which shifts with vertex distance.

What is the optical center (OC) of a lens?

The point where light passes with no prismatic deviation; ideally placed in front of the pupil.

Prism base directions?

Base-up (BU), base-down (BD), base-in (BI, toward the nose), base-out (BO, toward the ears).

Apex vs base of a prism — light bends toward which?

Light bends toward the base; the image displaces toward the apex.

Convergence requirement at near vs distance?

Near PD is smaller than distance PD because the eyes converge for near tasks.

What is magnification's relationship to plus power?

Plus lenses magnify (enlarge) the image; minus lenses minify (reduce) it.

Power in an oblique meridian (approx)?

Cylinder power in a meridian θ from the axis ≈ cyl × sin²θ added to the sphere.

Reading the lab order: what does '−3.00 DS' mean?

−3.00 diopters sphere with no cylinder (a purely spherical lens).

What is induced anisometropic prism at near?

Vertical prism imbalance from unequal lens powers when the patient reads below the OCs (Prentice's rule per eye).

Which structure bends the most light entering the eye?

The cornea — about two-thirds of the eye's focusing power (large air-to-tissue index change).

Role of the crystalline lens?

Fine-tunes focus by accommodation; its stiffening with age causes presbyopia.

The light-sensitive layer at the back of the eye that converts light into neural signals.

The small central retinal area responsible for the sharpest, most detailed central vision.

What does the iris do?

Controls the amount of light entering the eye by changing the pupil size.

What is the optic disc / blind spot?

Where the optic nerve exits the retina — it has no photoreceptors, creating a natural blind spot.

Myopia — where does light focus, and the correction?

In front of the retina (eye too long / cornea too steep); corrected with minus lenses.

Hyperopia — where does light focus, and the correction?

Behind the retina (eye too short / cornea too flat); corrected with plus lenses.

Uneven corneal/lens curvature focusing light at two meridians; corrected with cylinder.

Age-related loss of accommodation (mid-40s onward); corrected with a near add.

The condition of no refractive error — light focuses exactly on the retina.

What is accommodation?

The eye's ability to increase its focusing power for near objects by changing lens shape.

What does 'add' in a prescription mean?

Extra plus power for the near (reading) zone, added to the distance prescription for presbyopia.

OD, OS, OU — what do they mean?

OD = right eye (oculus dexter), OS = left eye (oculus sinister), OU = both eyes (oculus uterque).

Order of the prescription columns?

Sphere, Cylinder, Axis, then Add and any Prism/Base.

What is the axis in a prescription?

The meridian (1–180°) along which the cylinder's correcting power is oriented.

The tough white outer coat of the eye that protects and maintains its shape.

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What is a diopter (D)?: The unit of lens power — the reciprocal of the focal length in meters. Power (D) = 1 ÷ f (m).
Lens power formula?: Power (D) = 1 ÷ focal length (meters). A +2.50 D lens focuses at 1 ÷ 2.50 = 0.40 m = 40 cm.
Focal length of a +5.00 D lens?: f = 1 ÷ 5.00 = 0.20 m = 20 cm.
Plus (convex) lens — effect on light?: Converges parallel rays to a real focal point; corrects hyperopia and presbyopia; thicker in the center.
Minus (concave) lens — effect on light?: Diverges parallel rays to a virtual focal point on the incoming side; corrects myopia; thicker at the edge.
What is Prentice's rule?: Prism (Δ) = decentration (cm) × lens power (D). Gives the prism induced by looking away from the optical center.
Prism from looking 5 mm off-center through a 4.00 D lens?: Δ = 0.5 cm × 4.00 D = 2.0 Δ. (Convert 5 mm → 0.5 cm first.)
How is prescribed prism ground into a lens?: By decentering the lens (Prentice's rule) or by a prism-grind, moving the optical center relative to the visual axis.
Unit of prism?: The prism diopter (Δ): 1 Δ deviates light 1 cm at 1 m (1 cm per meter).
How do prisms at right angles combine?: By vector (Pythagorean) addition: resultant = √(a² + b²). E.g. 3 Δ up + 4 Δ out = √25 = 5 Δ.
Lens transposition — the 3 steps?: 1) New sphere = sphere + cylinder. 2) Reverse the cylinder sign. 3) Rotate the axis 90° (keep 1–180).
Transpose +2.00 +1.00 × 090.: → +3.00 −1.00 × 180 (optically identical, minus-cyl form).
What is the spherical equivalent (SE)?: SE = sphere + (cylinder ÷ 2). For −2.00 −1.00 × 090, SE = −2.50 D.
What is vertex distance?: The distance from the back surface of the lens to the front of the cornea.
Effect of moving a minus lens away from the eye?: It acts stronger (more minus). A plus lens moved away acts weaker.
When is vertex-distance compensation significant?: Around ±4.00 D and stronger; weak prescriptions are negligibly affected.
What is base curve?: The front (or reference) surface curvature of a lens, read in diopters with a lens clock; sets the lens's form.
Best-form (corrected-curve) lens — purpose?: A base curve chosen to minimize oblique (marginal) astigmatism for off-axis gaze.
How do you estimate a lens's total power from its surfaces?: Add the front and back surface powers algebraically (with sign).
Effective power vs nominal power?: Effective power is the lens's power experienced at the eye's plane, which shifts with vertex distance.
What is the optical center (OC) of a lens?: The point where light passes with no prismatic deviation; ideally placed in front of the pupil.
Prism base directions?: Base-up (BU), base-down (BD), base-in (BI, toward the nose), base-out (BO, toward the ears).
Apex vs base of a prism — light bends toward which?: Light bends toward the base; the image displaces toward the apex.
Convergence requirement at near vs distance?: Near PD is smaller than distance PD because the eyes converge for near tasks.
What is magnification's relationship to plus power?: Plus lenses magnify (enlarge) the image; minus lenses minify (reduce) it.
Power in an oblique meridian (approx)?: Cylinder power in a meridian θ from the axis ≈ cyl × sin²θ added to the sphere.
Reading the lab order: what does '−3.00 DS' mean?: −3.00 diopters sphere with no cylinder (a purely spherical lens).
What is induced anisometropic prism at near?: Vertical prism imbalance from unequal lens powers when the patient reads below the OCs (Prentice's rule per eye).
Which structure bends the most light entering the eye?: The cornea — about two-thirds of the eye's focusing power (large air-to-tissue index change).
Role of the crystalline lens?: Fine-tunes focus by accommodation; its stiffening with age causes presbyopia.
What is the retina?: The light-sensitive layer at the back of the eye that converts light into neural signals.
What is the macula?: The small central retinal area responsible for the sharpest, most detailed central vision.
What does the iris do?: Controls the amount of light entering the eye by changing the pupil size.
What is the optic disc / blind spot?: Where the optic nerve exits the retina — it has no photoreceptors, creating a natural blind spot.
Myopia — where does light focus, and the correction?: In front of the retina (eye too long / cornea too steep); corrected with minus lenses.
Hyperopia — where does light focus, and the correction?: Behind the retina (eye too short / cornea too flat); corrected with plus lenses.
What is astigmatism?: Uneven corneal/lens curvature focusing light at two meridians; corrected with cylinder.
What is presbyopia?: Age-related loss of accommodation (mid-40s onward); corrected with a near add.
What is emmetropia?: The condition of no refractive error — light focuses exactly on the retina.
What is accommodation?: The eye's ability to increase its focusing power for near objects by changing lens shape.
What does 'add' in a prescription mean?: Extra plus power for the near (reading) zone, added to the distance prescription for presbyopia.
OD, OS, OU — what do they mean?: OD = right eye (oculus dexter), OS = left eye (oculus sinister), OU = both eyes (oculus uterque).
Order of the prescription columns?: Sphere, Cylinder, Axis, then Add and any Prism/Base.
What is the axis in a prescription?: The meridian (1–180°) along which the cylinder's correcting power is oriented.
What is the sclera?: The tough white outer coat of the eye that protects and maintains its shape.
What is the cornea made transparent by?: Its avascular, regular collagen arrangement and controlled hydration.
Where is aqueous humor and what does it do?: Fluid in the anterior chamber that nourishes the cornea/lens and maintains intraocular pressure.
What is the pupillary (near) reflex triad?: Convergence, accommodation, and pupil constriction when shifting to a near object.
Index of refraction of CR-39 plastic?: 1.498 — the standard plastic; excellent optics (Abbe ≈ 58) but thick in strong Rx.
Index of crown glass?: 1.523 — excellent optics (Abbe ≈ 59); heavy and breakable, rarely dispensed now.
Index of polycarbonate?: 1.586 — most impact-resistant; low Abbe (≈ 30); inherently blocks UV.
Index of Trivex?: ≈ 1.53 — light, impact-resistant, drillable; higher Abbe (≈ 43–45) than polycarbonate.
Common high-index values?: 1.60, 1.67, and 1.74 — progressively thinner/flatter for strong Rx, with lower Abbe.
What is the Abbe value?: A measure of chromatic dispersion. High Abbe = crisp optics; low Abbe = color fringing/edge blur.
Higher refractive index means…?: The material bends light more, so the lens can be made thinner and flatter for the same power.
Most impact-resistant common lens material?: Polycarbonate — the standard for children's, safety, and sports eyewear.
Best material for rimless mounts?: Trivex — light and drillable; polycarbonate can crack at drill holes.
How does a photochromic lens darken?: It reacts to UV light, not visible light, becoming dark outdoors and clearing indoors.
Why do photochromics darken less in a car?: The windshield blocks most UV, the trigger they need, so they stay relatively clear.
What do polarized lenses do?: Block reflected horizontal glare from roads/water using a polarizing filter.
Purpose of an anti-reflective (AR) coating?: Reduces surface reflections, improving light transmission, night vision, and cosmetic clarity.
Purpose of a scratch-resistant (hard) coating?: Hardens the soft surface of plastic/high-index lenses to resist scratching.
FT-28 bifocal — what does '28' mean?: The width of the flat-top reading segment in millimeters (28 mm wide).
Executive (Franklin) bifocal?: A bifocal whose reading segment spans the entire width of the lens.
What is a trifocal?: A multifocal with distance, intermediate, and near zones (e.g. a 7×28 trifocal).
What is a progressive addition lens (PAL)?: A line-free multifocal with a gradual power change from distance through intermediate to near.
What is the add power?: The extra plus power in the near zone of a multifocal, supplied for presbyopia.
Bifocal segment styles?: Flat-top (FT/D-seg), round seg, curved-top, and executive/full-width.
What is a tint used for?: Cosmetic color, light reduction, or contrast enhancement; gradient or solid.
How is glass made impact-resistant?: By chemical or thermal (air) tempering, since glass is not inherently impact-resistant.
What does a mirror coating do?: Reflects a portion of incident light off the front surface to cut brightness; cosmetic too.
Specific gravity — why does it matter?: It drives lens weight; lower specific gravity (e.g. Trivex) gives lighter lenses.
Single-vision lens?: One power across the whole lens — corrects a single refractive distance need.
Aspheric lens benefit?: Flatter, thinner, lighter design that reduces magnification and distortion in plus lenses.
What does a lensmeter (lensometer) measure?: Sphere, cylinder, axis, add, and prism of a finished lens, and locates the optical center.
Why focus the lensmeter eyepiece first?: To eliminate the operator's accommodation so your eye doesn't add/remove power and bias readings.
Single clear lines with no second focus mean…?: A spherical lens (no cylinder correction).
How is cylinder axis read on a lensmeter?: Rotate until the single (sphere) lines and the triple (cylinder) lines are each sharp; note the axis.
What is a lens clock (Geneva lens measure)?: A 3-pin gauge that reads a surface's curvature (base curve) in diopters.
Lens clock calibration index?: Calibrated for crown glass, index 1.523; readings need correction on other materials.
On high-index material, the lens clock reads…?: Lower than the true surface power (it under-reads), requiring correction.
What does a distometer measure?: The vertex distance between the back of the lens and the cornea.
What is a pupillometer?: A corneal-reflection instrument that measures monocular and binocular PD accurately.
For an accurate distance PD with a pupillometer, fixate on…?: A distant target so the eyes are in parallel (non-converged) alignment.
Front-vertex (neutralizing) method for add — why?: It removes the influence of differing back-vertex distances between distance and near zones.
How is add power found on a lensmeter?: Subtract the distance sphere reading from the segment (near) sphere reading.
What does a thickness caliper measure?: Center and edge thickness of a lens, in millimeters.
How is prism read on a lensmeter?: By the displacement of the target center from the lensmeter's reticle center (in Δ).
Manual vs automated (digital) lensmeter?: Both read power/axis/add/prism; the automated unit displays values digitally, reducing operator error.
What is the marking/dotting step on a lensmeter?: Marking the optical center and the 180° (horizontal) reference for layout and prism checks.
PD ruler technique for monocular PD?: Measure from the nasal-bridge center to each pupil/corneal reflection separately.
What is a pattern (former) used for?: A template of the frame's eyewire shape used by the edger to cut the lens to size.
Geneva lens measure on a steeper surface reads…?: A higher diopter value (more curvature).
What instrument verifies that lenses meet the prescribed Rx before dispensing?: The lensmeter — used to check power, axis, add, prism, and OC against ANSI Z80.1 tolerances.
Binocular vs monocular PD?: Binocular PD is pupil-to-pupil total; monocular PD is each pupil's distance from the nose center, measured separately.
Why measure monocular PD?: Faces are rarely symmetric — it places each OC in front of its pupil to avoid unwanted prism.
Near PD vs distance PD?: Near PD is smaller because the eyes converge for near tasks.
What is pantoscopic tilt?: The angle where the bottom of the frame front sits closer to the face than the top.
OC adjustment guideline for pantoscopic tilt?: Lower the optical center ~1 mm for every 2° of pantoscopic tilt.
Effect of uncompensated tilt on a high-plus lens?: Unwanted vertical prism and oblique astigmatism.
What is face-form (panoramic) angle?: The horizontal wrap of the frame front so the lenses curve back toward the temples.
Where is a flat-top bifocal seg typically set?: At or just below the lower eyelid margin / lower limbus.
Where is a PAL fitting cross set?: At the patient's pupil center in primary gaze, per the manufacturer's layout.
Seg-height measured from where?: From the lowest point of the lens shape up to the desired seg top (or fitting cross).
Vertex distance — best definition?: From the back surface of the lens to the front of the cornea.
The boxing system encloses each lens in a…?: Rectangle (box) — used to standardize frame and decentration measurements.
A measurement (boxing)?: Horizontal width of the lens box — the eye size.
B measurement (boxing)?: Vertical height of the lens box.
DBL?: Distance between lenses — the bridge size (gap between the two lens boxes).
ED (effective diameter)?: The longest diagonal across the lens box from its geometric center; drives minimum blank size.
Reading '52□18 140' on a temple?: 52 mm eye size · 18 mm bridge (DBL) · 140 mm temple length.
Boxing (geometric) center PD?: A + DBL — the frame's mechanical center distance; compare to the patient PD to find decentration.
How much to decenter if frame PD > patient PD?: Decenter each lens inward by half the difference so each OC sits over the pupil.
Standard alignment / 'four-point touch' — what is it?: A properly adjusted frame rests evenly: both temples and both pads/sides contact without rocking.
Adjusting a frame that sits too high?: Lengthen the temple bend / adjust pads so the frame lowers to the proper vertex and pantoscopic angle.
Why warm a zyl (acetate) frame before adjusting?: Acetate becomes pliable with heat; adjusting it cold risks cracking the plastic.
Verifying seg height after edging?: Confirm the seg top sits at the marked height relative to the patient's pupil/lower lid.
Temple types?: Skull (most common), library (straight), comfort-cable, and riding-bow temples.
Bridge types on a frame?: Saddle, keyhole, and adjustable nose-pad bridges.
What does ANSI Z80.1 cover?: Tolerances for prescription (dress) ophthalmic lenses — power, cylinder, axis, add, and prism.
ANSI Z80.1 sphere power tolerance (≤6.50 D)?: ±0.13 D; above 6.50 D it is about ±2%.
ANSI Z80.1 cylinder axis tolerance trend?: Tightens as cylinder rises: ±14° (very low cyl), ±7°, ±5°, ±3°, down to ±2° (cyl >1.50 D).
ANSI Z80.1 add-power tolerance?: ±0.12 D for adds up to +4.00 D; ±0.18 D above.
What does ANSI Z87.1 cover?: Occupational and educational personal-eye-protection (safety eyewear) impact requirements.
Marking 'Z87+' on safety lenses means…?: The lenses meet the high-velocity (high-impact) requirement of ANSI Z87.1.
FDA impact-resistance rule citation?: 21 CFR 801.410 — dress (street-wear) eyeglass lenses must be impact-resistant.
The FDA drop-ball test?: A 5/8-inch (~16 g) steel ball is dropped 50 inches onto the lens, which must not fracture.
Are polycarbonate/Trivex individually drop-ball tested?: Usually no — they are certified impact-resistant by the manufacturer and exempt.
FDA rule vs ANSI Z87.1 — difference?: FDA 801.410 = minimum impact for dress eyewear; ANSI Z87.1 = higher-impact occupational safety eyewear.
What is the FTC Eyeglass Rule?: Prescribers must give the patient a copy of the eyeglass Rx at the end of the exam, free, without being asked.
Can a seller require purchase to release a prescription?: No — under the FTC Eyeglass Rule the Rx must be released regardless of whether the patient buys from you.
What does the FTC Contact Lens Rule do?: Provides similar Rx-release protections for contact lenses.
Scope of practice for an optician?: Interpret prescriptions and fit/measure/dispense eyewear — not diagnose or treat eye disease.
How is HIPAA relevant to opticians?: It requires safeguarding patients' protected health information (PHI) in the optical office.
Does state licensure for opticians vary?: Yes — some states license/certify opticians and others do not; ABO certification supports licensure where required.
Who administers the ABO Basic (NOCE) exam?: The American Board of Opticianry & National Contact Lens Examiners (ABO-NCLE).
What does an out-of-tolerance lens require?: Remaking the lens — it must meet ANSI Z80.1 before it is dispensed.
OSHA's role for prescription safety eyewear?: OSHA requires employers to provide ANSI Z87-compliant eye protection in hazardous workplaces.
UV protection responsibility when dispensing?: Advise UV-blocking lenses/coatings; polycarbonate and Trivex inherently block UV.
Focal length of a −2.00 D lens?: f = 1 ÷ 2.00 = 0.50 m = 50 cm (virtual, on the incoming-light side).
Decentration to make 3 Δ in a 6.00 D lens?: Δ = d(cm) × P, so d = 3 ÷ 6.00 = 0.5 cm = 5 mm.
Combine 2 Δ base-up and 1.5 Δ base-in.: Resultant = √(2² + 1.5²) = √6.25 = 2.5 Δ.
Resultant of 6 Δ and 8 Δ at right angles?: √(36 + 64) = √100 = 10 Δ.
What is sagittal depth (sag)?: The depth of a curve's bulge; relates surface power, lens diameter, and thickness.
Why does a stronger minus lens have thicker edges?: More diverging curvature is needed, removing material from the center and leaving the edge thick.
Compensated power for a strong lens worn closer than refracted?: Recompute with the effective-power/vertex formula; a minus lens worn closer needs slightly less minus.
Minus cylinder vs plus cylinder form — same lens?: Yes — they describe the identical lens; transposition converts between them.
Lensmaker's idea: power adds across two surfaces?: Approximate total power ≈ front surface power + back surface power.
What is chromatic aberration in optical terms?: Different wavelengths focus at slightly different points; worse with low-Abbe materials.
Image displacement through a prism?: Toward the apex; the eye rotates toward the apex to refixate.
Base-in prism is prescribed to help with…?: Convergence problems (it shifts images outward so the eyes converge less).
What is the choroid?: The vascular layer between the retina and sclera that nourishes the outer retina.
What is the vitreous humor?: The clear gel filling the posterior cavity that helps maintain the eye's shape.
What are rods and cones?: Retinal photoreceptors: rods for low-light/peripheral vision, cones for color and detail.
What is the fovea?: The cone-rich center of the macula giving the sharpest vision.
What is the limbus?: The border where the cornea meets the sclera.
What is the conjunctiva?: The thin membrane covering the white of the eye and the inner eyelids.
Anisometropia?: A significant difference in refractive power between the two eyes.
Why do hyperopes tire at near?: They must accommodate even for distance, leaving less reserve for sustained near work.
What is amblyopia?: Reduced vision in an eye that did not develop normally ('lazy eye').
What is the near point of accommodation?: The closest distance at which the eye can keep an object in clear focus.
UV protection of polycarbonate?: Inherently blocks essentially all UV up to about 380–400 nm.
Why might a patient see edge color fringes?: Low Abbe value (chromatic aberration), most noticeable peripherally in strong/large lenses.
Gradient tint?: A tint that is darker at the top and fades lighter toward the bottom.
Polarized lens axis orientation?: The filter is oriented vertically to block horizontally polarized reflected glare.
Photochromic activation depends on what two factors?: UV exposure and temperature — they darken more in cold, less in heat and in cars.
Difference between FT-28 and FT-35?: Segment width: 28 mm vs 35 mm reading area.
Round-seg bifocal use?: A small round reading segment; less image jump location but a curved dividing line.
Image jump in a bifocal?: The sudden prismatic shift as the eye crosses the seg line; least with the OC at the seg top (executive/no-jump).
What is a Trivex advantage over polycarbonate besides Abbe?: Lighter weight (lower specific gravity) and better tensile strength for drilled mounts.
Aspheric lens trade-off?: Flatter/thinner but requires correct vertex/pantoscopic fitting to perform well.
Tinted lens for general sun wear density?: Commonly ~70–85% absorption (about 15–30% light transmission).
Mirror coating is applied to which surface?: The front (convex) surface of the lens.
What is a high-index trade-off?: Thinner/lighter but typically lower Abbe (more aberration) and more surface reflection (AR recommended).
Bifocal add typically ranges?: About +0.75 D to +3.00 D depending on the patient's near demand and age.
Reading add on a flat-top with the lensmeter front-up?: Use the front-vertex (neutralizing) method: read distance, then seg; subtract.
Compound prism on a lensmeter — how found?: Vector-combine the vertical and horizontal target displacements (Pythagorean).
Spotting/marking three dots on a lens — purpose?: Marks the optical center (middle dot) and the horizontal 180° reference.
Why is the lensmeter target a cross of single + triple lines?: Singles read one principal meridian (sphere), triples the other (cylinder); axis when both are sharp.
Geneva lens clock correction factor depends on?: The lens material's actual index vs the 1.523 calibration index.
Distometer scale reads in?: Millimeters of vertex distance.
Automated lensmeter advantage?: Faster, reduces operator accommodation/parallax error, and reads progressive power maps.
Pupillometer corneal reflection method?: Uses the light reflex on the cornea to mark each pupil center for monocular PD.
Seg height too high — symptom?: The patient hits the reading zone too soon and complains the distance field is small.
Seg height too low — symptom?: The patient must depress their gaze excessively or tilt the head to read.
Pantoscopic tilt typical range?: About 8°–12° for everyday wear.
Wrap (face-form) typical range?: A few degrees for dress eyewear; high-wrap sport frames need power compensation.
Vertex distance typical value?: Roughly 12–14 mm for standard fittings.
Decentration per eye if patient PD 62, frame PD 70?: Total in-decentration 8 mm → 4 mm inward per lens.
Minimum blank size estimate?: ED + 2 × (decentration) + a few mm tolerance.
Standard alignment checks?: Frame front straight, even temple spread, level fronts, proper pad/temple contact (four-point touch).
Adjusting nose pads to lower a frame?: Widen/spread the pads so the frame settles lower on the nose.
Adjusting temples for a frame sliding down?: Add or increase the temple bend behind the ear (earpiece) for grip.
Why measure seg height with the frame on the patient?: It must reflect the actual fitted pantoscopic tilt and how the frame sits.
Monocular PD use case (high power)?: Essential — it prevents induced prism by centering each OC over its own pupil.
Frame PD vs patient PD mismatch effect if uncorrected?: Off-center OCs induce unwanted (usually base-out or base-in) prism.
ANSI Z80.1 cylinder power tolerance (≤2.00 D cyl)?: About ±0.13 D.
ANSI Z80.1 prism tolerance at the OC (single vision)?: Between the eyes: vertical imbalance ±0.33 Δ, horizontal ±0.67 Δ.
Z87-2 marking means?: Prescription safety eyewear meeting ANSI Z87.1 (the '-2' denotes Rx).
Steel ball weight/size in the FDA drop-ball test?: 5/8 inch diameter, about 16 grams (0.56 oz).
Drop height in the FDA drop-ball test?: 50 inches.
Who must receive a copy of the eyeglass Rx, and when?: The patient, at the completion of the eye exam, automatically and free (FTC Eyeglass Rule).
Does the FTC rule require a fitting fee waiver?: No — but the prescription itself must be released without conditioning it on a purchase.
Optician vs optometrist vs ophthalmologist?: Optician dispenses eyewear; optometrist examines/prescribes; ophthalmologist is a medical/surgical eye physician.
Where ABO certification is required by a state, it supports…?: Meeting that state's licensure standard for opticians.
Recordkeeping/PHI handling standard for opticians?: HIPAA — protect patients' protected health information.

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By Career EmployerUpdated Jun 19, 2026

200+ free ABO flashcards — 4 ways to study

ABO Flashcard of the Day

The classic card. Do you know this one?

Click Study Flashcards above to open the flashcard hub — hundreds of ABO opticianry cards you can flip, match, type, or quiz yourself on. Every card is drawn from the ABO-NCLE Basic (NOCE) content outline, so you study exactly what the opticianry exam tests.^[1] Pair them with our free practice questions and study guide.

ABO Flashcard Study Modes

Most flashcard sites give you one thing: a card to flip. Ours has four modes so you can both learn the material and prove you know it — the difference between recognizing an answer and recalling it under pressure.

Flip (Study) — the classic card. Flip term ↔ definition, shuffle the deck, and mark each card “Got it” or “Still learning.”
Match (Game) — a timed game: pair each term to its definition as fast as you can. Great for cementing lens materials, tube colors of standards, and the boxing-system measurements.
Type (Recall) — read the definition and type the term. Typing forces true active recall instead of passive recognition.
Quiz (Test) — multiple-choice questions generated from the cards, so you can self-test exactly like exam day.

Free ABO opticianry flashcards from Career Employer — active recall for the ABO Basic (NOCE) exam

Why Flashcards Work for the ABO Exam

Flashcards aren’t busywork — they’re built on active recall: pulling an answer out of memory strengthens it far more than re-reading notes. Pair that with spacing — short sessions across several days rather than one cram — and you retain more in less time.

That matters on the ABO, where facts like the dioptric power formula, Prentice’s rule, lens index and Abbe values, the boxing-system measurements, and the ANSI/FDA standards must be instantly available. Used alongside our practice questions and study guide, flashcards turn review time into measurable progress.

ABO Flashcards by Topic

The cards are organized by the ABO-NCLE content areas. Weight your study toward the heaviest one — Ophthalmic Optics is 25% of the scored items:^[1]

ABO Basic (NOCE) content areas and their scored-item weight
ABO content area	Weight
Ophthalmic Optics	25%
Ophthalmic Products	20%
Dispensing Procedures	20%
Instrumentation	15%
Ocular Anatomy & Refraction	10%
Laws, Regulations & Standards	10%

How to Get the Most Out of These Flashcards

Start early, review daily. Begin flashcards as you cover each content area, not the week before — a few minutes a day beats one marathon session.
Use Type and Quiz, not just Flip. Recognizing the right answer is easy; recalling and choosing it is the real test.
Drill the optics formulas hardest. Power = 1 ÷ f, Prentice’s rule, and transposition are the densest, most-tested ABO content — make them automatic.
Mirror the exam weighting. Spend the most time on Ophthalmic Optics — it carries the most points.
Lock in the high-yield facts. Lens index and Abbe values, the boxing-system letters, and the ANSI Z80.1 vs Z87.1 split are repeatable points.
Then prove it. When the cards feel easy, confirm with our practice questions — aim for strong, even scores across all six areas before exam day.

ABO Flashcards FAQ

Hundreds of free ABO flashcards, organized across the six content areas tested on the ABO Basic (NOCE) opticianry exam — from lens optics, prism, and transposition through lens materials, frame fitting and PD measurement, the lensmeter, and ANSI/FDA/FTC standards. They're free to use with no account required.

References

1.American Board of Opticianry & National Contact Lens Examiners (ABO-NCLE). “ABO-NCLE Basic Exam Candidate Handbook (February 2025) & NOCE Content Outline.” abo-ncle.org. ↑
2.American National Standards Institute (ANSI). “ANSI Z80.1 — Prescription Ophthalmic Lenses & Z87.1 — Personal Eye Protection.” ansi.org. ↑
3.U.S. Food & Drug Administration (FDA). “21 CFR 801.410 — Impact-Resistant Lenses in Eyeglasses.” fda.gov / eCFR. ↑

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