ABO Optician — All Questions

What is the focal length of a +2.00 D lens?

• a.10 cm
• b.50 cm✓
• c.25 cm
• d.200 cm

Focal length in meters equals 1 divided by the lens power in diopters. 1 / 2.00 = 0.50 m, or 50 cm. A stronger plus lens would have a shorter focal length.

A lens has a focal length of 25 cm. What is its dioptric power?

• a.+2.00 D
• b.+25.00 D
• c.+0.25 D
• d.+4.00 D✓

Power equals 1 divided by focal length in meters. 25 cm = 0.25 m, so 1 / 0.25 = +4.00 D. Focal length and power are reciprocals of one another.

Light traveling from a less dense medium into a more dense medium will do what?

• a.Stop completely
• b.Speed up and bend away from the normal
• c.Slow down and bend toward the normal✓
• d.Continue at the same speed

When light enters a denser medium (higher index of refraction) it slows down and refracts toward the normal. This bending of light is the basis of how lenses focus rays.

Which lens material has the highest Abbe value, meaning the least chromatic aberration?

• a.1.67 high-index
• b.CR-39 (1.498)✓
• c.Polycarbonate
• d.1.74 high-index

CR-39 plastic has an Abbe value near 58, the highest among these options, so it produces the least chromatic aberration. Higher-index materials such as 1.67 and 1.74 have lower Abbe values and more color dispersion.

A minus (concave) lens forms what type of image and has what type of focal point?

• a.No image at all
• b.Real image, real focal point
• c.Virtual image, virtual focal point✓
• d.Real image, virtual focal point

A concave minus lens diverges light, so its rays only appear to come from a point behind the lens, creating a virtual focal point and a virtual, upright image.

The power of a lens surface increases as its radius of curvature does what?

• a.Stays the same
• b.Decreases (steeper surface)✓
• c.Increases (flatter surface)
• d.Doubles the index

Surface power is inversely related to radius of curvature. A shorter radius means a steeper, more curved surface and greater power; a longer radius means a flatter surface and less power.

What is the total power of a lens with a front surface of +6.00 D and a back surface of -2.00 D (thin lens approximation)?

• a.+3.00 D
• b.+4.00 D✓
• c.+8.00 D
• d.-4.00 D

For a thin lens, total power is the algebraic sum of the front and back surface powers. +6.00 + (-2.00) = +4.00 D.

Vergence describes what property of light?

• a.Its polarization angle
• b.Its intensity
• c.Its color wavelength
• d.The spreading or converging of light rays✓

Vergence is the degree to which light rays diverge or converge, measured in diopters. Plus lenses add convergence (plus vergence); minus lenses add divergence (minus vergence).

The base curve of a lens refers to which surface?

• a.The bevel edge
• b.The segment line
• c.The temple curve
• d.The reference curve from which the lens is made, usually the front✓

Base curve is the fixed reference curve used as the starting point for making a lens, conventionally the front surface. The back surface is then ground to achieve the required prescription power.

Add power on a multifocal lens represents what?

• a.The prism amount
• b.The distance sphere power
• c.The additional plus power for near vision✓
• d.The cylinder axis

The add is the extra plus power in the reading segment that supplements the distance prescription to help a presbyopic patient see clearly at near. It is always a plus value.

If the distance Rx is -3.00 D and the add is +2.00 D, what is the total power in the reading portion?

• a.-5.00 D
• b.+2.00 D
• c.-1.00 D✓
• d.-3.00 D

The near power equals the distance sphere plus the add. -3.00 + 2.00 = -1.00 D in the reading zone.

Vertex distance is the measured space between what two points?

• a.The frame front and the temple
• b.The two pupils
• c.The back of the lens and the front of the cornea✓
• d.The optical center and the segment

Vertex distance is the distance from the back surface of the lens to the front of the eye (cornea). It matters most for higher-powered prescriptions where a change alters effective power.

Chromatic aberration is caused by what?

• a.Different wavelengths of light focusing at different points✓
• b.Uneven frame pressure
• c.Scratches on the lens
• d.Anti-reflective coating

Because a lens refracts short (blue) wavelengths more than long (red) wavelengths, colors focus at slightly different points, producing color fringing. Materials with a low Abbe value show it most.

Which of the following describes a plano lens?

• a.+2.00 D of plus power
• b.A lens with no refractive power✓
• c.A lens with cylinder only
• d.A high minus lens

Plano means flat or zero power. A plano lens has no sphere or cylinder power and does not change vergence, though it may still carry a tint or coating.

Spherical aberration in a lens is best described as what?

• a.Color separation of white light
• b.Distortion from prism
• c.Peripheral rays focusing differently than central rays✓
• d.Reflection off both surfaces

Spherical aberration occurs when light passing through the outer (peripheral) zones of a lens focuses at a different point than light through the center, blurring the image. Aspheric designs reduce this effect.

The index of refraction of a material is a ratio comparing what?

• a.Speed of light in a vacuum to speed of light in the material✓
• b.Weight to volume
• c.Diameter to thickness
• d.Front curve to back curve

Index of refraction (n) equals the speed of light in a vacuum divided by the speed of light in the material. A higher index means light slows more, allowing thinner lenses for a given power.

An aspheric lens design primarily reduces what?

• a.Peripheral distortion and lens bulge✓
• b.Tint density
• c.Segment height
• d.Weight of the frame

Aspheric lenses flatten the front curve and change curvature toward the edges, which reduces peripheral aberrations and the magnified, bulging appearance of higher-plus lenses.

Compared with crown glass, polycarbonate is valued mostly for what property?

• a.Lowest cost
• b.Scratch resistance without coating
• c.Higher Abbe value
• d.High impact resistance✓

Polycarbonate is highly impact resistant, making it the preferred material for safety, children's, and sports eyewear. Its drawbacks include a low Abbe value and a soft surface that needs a scratch coating.

Snell's law governs which optical phenomenon?

• a.Polarization
• b.Reflection intensity
• c.Diffraction
• d.Refraction of light at a surface✓

Snell's law relates the angle of incidence and angle of refraction to the indices of the two media, describing how much light bends when passing between materials of different density.

As the index of refraction of a lens material increases, for a given power the lens can be made which way?

• a.Softer
• b.Thinner✓
• c.More curved
• d.Thicker

Higher-index materials bend light more efficiently, so less material and shallower curves are needed to achieve a given power, producing a thinner and often lighter lens.

A prism deviates light in which direction?

• a.Along the axis
• b.Toward the base
• c.Toward the apex✓
• d.There is no deviation

Light passing through a prism bends toward the thick base, while the image seen through it displaces toward the thin apex. Prism power is measured in prism diopters.

One prism diopter of power displaces an image by how much and at what distance?

• a.1 m at 1 meter
• b.1 mm at 1 meter
• c.1 cm at 1 meter✓
• d.1 inch at 1 foot

One prism diopter deviates a ray of light 1 centimeter at a distance of 1 meter. Prism diopters are the standard unit for specifying and measuring prismatic effect.

Which lens curve produces plus power?

• a.A prism surface
• b.A convex surface✓
• c.A flat surface
• d.A concave surface

A convex surface is thicker in the middle and converges light, producing plus power. A concave surface is thinner in the middle, diverges light, and produces minus power.

Effective power change from vertex distance is most significant for which prescriptions?

• a.High-powered lenses✓
• b.Cylinder-only lenses
• c.Plano lenses
• d.Low-powered lenses

The further a lens is moved from the eye, the more its effective power changes, and this effect grows with lens power. For high plus or minus Rx, vertex compensation is important; weak Rx changes negligibly.

The optical center of a lens is the point where what happens?

• a.The bevel is thickest
• b.The cylinder axis crosses
• c.Light passes with no prismatic deviation✓
• d.Maximum prism occurs

At the optical center, light passes straight through with zero prismatic effect. Moving the line of sight away from the optical center introduces prism, per Prentice's rule.

A photochromic lens changes tint in response to what?

• a.Blue light from screens
• b.Ultraviolet (UV) radiation✓
• c.Polarized reflections
• d.Temperature only

Photochromic lenses darken when exposed to ultraviolet light, which is why they may not darken fully inside a car whose windshield blocks UV. They lighten again when UV exposure decreases.

Anti-reflective (AR) coating improves vision primarily by doing what?

• a.Blocking UV only
• b.Increasing prism
• c.Reducing surface reflections and increasing light transmission✓
• d.Adding tint

AR coating reduces reflections off the lens surfaces, increasing the amount of light transmitted to the eye and reducing glare and ghost images, which improves visual clarity and cosmetic appearance.

A polarized lens reduces glare best from which source?

• a.Horizontal reflective surfaces like water and roads✓
• b.Digital device blue light
• c.Indoor fluorescent light
• d.Direct overhead sunlight only

Polarized filters block horizontally polarized light, which is the glare reflected off flat horizontal surfaces such as water, snow, and road pavement, greatly improving comfort and contrast outdoors.

What does the term 'minimum blank size' refer to?

• a.The smallest segment
• b.The smallest frame available
• c.The smallest lens blank that will cut out to fill the frame✓
• d.The smallest bevel angle

Minimum blank size (MBS) is the smallest diameter uncut lens needed to fully cut the shape into a given frame after accounting for decentration, ensuring the lens covers the entire eyewire.

Cylinder power in a lens corrects for what refractive condition?

• a.Presbyopia
• b.Color blindness
• c.Astigmatism✓
• d.Simple myopia

Cylinder power corrects astigmatism, in which the eye focuses light at different meridians unequally. The cylinder is oriented at a specified axis to counter the meridian needing correction.

Transpose the Rx: +2.00 -1.00 x 090 into plus-cylinder form.

• a.+1.00 -1.00 x 090
• b.+2.00 +1.00 x 090
• c.+1.00 +1.00 x 180✓
• d.+3.00 -1.00 x 180

To transpose: add the sphere and cylinder for the new sphere (+2.00 + -1.00 = +1.00), change the cylinder sign (+1.00), and rotate the axis 90 degrees (090 becomes 180). Result: +1.00 +1.00 x 180.

Transpose the Rx: -3.00 +2.00 x 045 into minus-cylinder form.

• a.-5.00 +2.00 x 135
• b.-1.00 +2.00 x 045
• c.-1.00 -2.00 x 135✓
• d.-3.00 -2.00 x 045

New sphere = -3.00 + 2.00 = -1.00; change cylinder sign to -2.00; rotate axis 90 degrees (045 to 135). Result: -1.00 -2.00 x 135.

In the Rx -2.50 -0.75 x 180, what does the 180 represent?

• a.The sphere power
• b.The prism base
• c.The add power
• d.The axis of the cylinder✓

The number after the 'x' is the cylinder axis, expressed 1 to 180 degrees, indicating the orientation of the cylinder correction. Here the axis is 180 degrees.

A patient has Rx OD -1.00 DS. What does 'DS' indicate?

• a.Decentration standard
• b.Distance seg
• c.Double segment
• d.Diopters sphere with no cylinder✓

DS stands for diopters sphere, meaning the lens is spherical only with no cylinder or axis. The prescription is simply -1.00 D of sphere.

Per ANSI Z80.1 tolerances, verifying a finished single-vision lens checks that the measured power falls within what?

• a.Half the prescribed power
• b.Exactly the prescribed power with zero deviation
• c.Twice the prescribed power
• d.An allowed tolerance range of the prescribed power✓

ANSI Z80.1 defines acceptable tolerances for sphere, cylinder, axis, add, and prism. A lens passes if its measured values fall within the standard's allowed range, not necessarily an exact match.ANSI Z80

A lens is decentered 4 mm from the optical center for a +5.00 D lens. How much prism results (Prentice's rule)?

• a.5.0 prism diopters
• b.1.0 prism diopter
• c.2.0 prism diopters✓
• d.0.4 prism diopters

Prentice's rule: prism = decentration in cm x power. 4 mm = 0.4 cm; 0.4 x 5.00 = 2.0 prism diopters.

When reading an Rx, which value is always a plus number on a bifocal?

• a.The sphere
• b.The add✓
• c.The axis
• d.The cylinder

The add power on a multifocal is always additional plus power for near vision, so it is written as a positive value regardless of the distance prescription.

Segment height is best defined as what?

• a.The pantoscopic tilt
• b.The horizontal distance between segments
• c.The width of the bifocal
• d.The vertical distance from the lowest point of the lens to the top of the segment line✓

Segment height is measured vertically from the lowest edge of the lens (or the deepest part of the eyewire) up to the top of the segment line, positioning the reading area correctly.

Monocular PD is measured from what to what?

• a.The center of the bridge of the nose to the center of each pupil✓
• b.Pupil to pupil
• c.Ear to ear
• d.Lens edge to lens edge

Monocular PD is the distance from the center of the nasal bridge to the center of each pupil individually. It accounts for facial asymmetry better than a single binocular PD.

A binocular distance PD of 64 mm typically corresponds to what near PD range?

• a.66 to 68 mm
• b.64 mm exactly
• c.70 mm
• d.60 to 62 mm✓

Because the eyes converge for near tasks, the near PD is smaller than the distance PD, usually by about 3 to 4 mm total. A 64 mm distance PD is roughly 60 to 61 mm at near.

Compensated (effective) power differs from the prescribed power mainly due to what?

• a.Bridge size
• b.Vertex distance and lens tilt✓
• c.Frame color
• d.Lens tint

When a high-powered lens sits at a vertex distance or tilt different from where it was refracted, its effective power on the eye changes, so a compensated power is calculated to preserve the intended correction.

A -8.00 D lens is moved closer to the eye. Its effective minus power does what?

• a.Decreases (less minus effect)✓
• b.Stays exactly the same
• c.Increases (more minus effect)
• d.Becomes plus power

For a minus lens moved closer to the eye, the effective power decreases; moved farther away, the effective minus power increases. Vertex compensation adjusts for this in high prescriptions.

Neutralizing a lens with a lensmeter finds what point?

• a.The point where the target is clear with no prism, the optical center✓
• b.The bevel apex
• c.The frame temple
• d.The segment top

On a lensmeter, the operator centers the lens so the mires (target) are clear and centered, identifying the optical center where there is no prismatic deviation, then reads sphere, cylinder, axis, and add.

Hand neutralization of an unknown lens uses what technique?

• a.Weighing the lens
• b.Reading the frame stamp
• c.Measuring edge thickness
• d.Moving the lens and observing target movement to add opposite power✓

In hand neutralization, an optician moves the lens across a target line; the direction of apparent movement indicates plus or minus, and trial lenses of opposite power are added until movement stops.

With-the-rule astigmatism typically has the cylinder axis oriented near what?

• a.Axis 135
• b.Axis 180 in minus cylinder✓
• c.Axis 45
• d.Axis 90 in plus cylinder

With-the-rule astigmatism has the steeper corneal meridian vertical, corrected with minus cylinder axis at or near 180 degrees. This is the most common form of astigmatism.

An Rx reads OD +1.50 -0.50 x 090, OS +1.50 -0.50 x 090, Add +2.25. What is the near power in each eye?

• a.+3.75 -2.75 x 090
• b.+2.25 -0.50 x 090
• c.+3.75 -0.50 x 090✓
• d.+1.50 -0.50 x 090

Near sphere = distance sphere + add = +1.50 + 2.25 = +3.75. The cylinder and axis carry through unchanged. Near Rx: +3.75 -0.50 x 090 in each eye.

Prism prescribed as '2 base out' in each eye is used to help with what?

• a.Reading add
• b.Convergence or divergence problems (horizontal)✓
• c.Vertical alignment
• d.Color vision

Base out and base in prism address horizontal deviations of the eyes, aiding fusion for esophoria or exophoria. Vertical deviations use base up or base down prism.

A patient needs 3 prism diopters base down in the right lens. If the lens is +2.00 D, how much decentration achieves this (Prentice's rule)?

• a.6.0 cm down
• b.1.5 cm (raise the OC 15 mm)✓
• c.0.67 cm up
• d.3.0 cm down

Prentice's rule solved for decentration: cm = prism / power = 3 / 2.00 = 1.5 cm. To create base-down prism with a plus lens, the optical center is raised 15 mm relative to the pupil.

Slab-off prism is used to correct what condition in a multifocal wearer?

• a.Excess add power
• b.Horizontal PD error
• c.A scratched segment
• d.Vertical imbalance at near between the two eyes✓

Slab-off grinds prism into one lens to compensate for the vertical prism imbalance created at the reading level when the two eyes have unequal Rx (anisometropia), restoring comfortable near fusion.

The written Rx 'OU' means what?

• a.Left eye only
• b.Over-refraction
• c.Both eyes (oculus uterque)✓
• d.Right eye only

OU is the Latin abbreviation oculus uterque, meaning both eyes. OD refers to the right eye and OS to the left eye.

Compensated power calculations are most critical when the fitted vertex distance differs from what?

• a.The seg height
• b.The frame PD
• c.The refracted vertex distance✓
• d.The base curve

The refraction is done at a specific vertex distance; when the dispensed frame sits at a different vertex distance, the effective power shifts, so compensation restores the intended power at the eye.

A spherical equivalent of the Rx -2.00 -1.00 x 180 is what?

• a.-2.00 D
• b.-3.00 D
• c.-1.50 D
• d.-2.50 D✓

Spherical equivalent = sphere + one-half the cylinder = -2.00 + (-1.00 / 2) = -2.00 + (-0.50) = -2.50 D. It represents the average dioptric power of the lens.

When both eyes require decentration for a smaller PD than the frame, the optical centers are moved which way?

• a.Nasally (inward)✓
• b.Temporally (outward)
• c.Vertically only
• d.Not at all

When the patient's PD is smaller than the frame's distance between lens centers, the optical centers must be decentered inward (nasally) to line up with the pupils and avoid unwanted prism.

Reading an Rx that lists 'BO' after a prism value indicates the base is oriented how?

• a.Base in
• b.Base down
• c.Base out✓
• d.Base up

BO stands for base out, meaning the thick base of the prism points toward the ear (temporal side). BI means base in (toward the nose), BU base up, and BD base down.

To relieve a frame that sits too low on the face, the optician should adjust what?

• a.Increase pantoscopic tilt
• b.Widen the temples
• c.Loosen the temples
• d.Tighten or narrow the nose pads/bridge✓

If the frame slides down, narrowing or tightening the nose pads (or choosing a smaller bridge) raises the frame and improves the fit. Adjusting the bridge controls how high the frame rides.

Pantoscopic tilt refers to what?

• a.The vertical seg placement
• b.The temple bend behind the ear
• c.The bottom of the frame tilting closer to the face than the top✓
• d.The frame wrapping around the head

Pantoscopic tilt is the forward tilt in which the lower rim sits closer to the cheeks than the upper rim. A modest pantoscopic tilt aligns the optical axis with the downward gaze for reading.

If a patient complains a new progressive lens has narrow, distorted side vision, what is the most likely cause of unavoidable blur?

• a.Too much tint
• b.The AR coating
• c.A scratched lens
• d.Peripheral aberrations inherent to progressive design✓

All progressive lenses have zones of peripheral (lateral) blur and swim as a trade-off for the seamless power progression. Proper fitting minimizes but cannot fully eliminate these peripheral aberrations.

Which lens material is required for a child's everyday eyewear for safety reasons?

• a.CR-39
• b.Polycarbonate or Trivex✓
• c.Crown glass
• d.1.74 high-index

Impact-resistant materials such as polycarbonate or Trivex are strongly recommended for children because of their superior shatter resistance, protecting the eyes from injury during active play.

A patient says their bifocal segment is too high and they see the line while walking. The correct fix is to do what?

• a.Add more add power
• b.Raise the segment
• c.Lower the segment height in a remake or raise the frame✓
• d.Increase the tint

If the seg line interferes with distance walking vision, the segment sits too high; lowering the seg height (or adjusting the frame to sit higher) moves the line down out of the primary distance gaze.

MPD (monocular PD) is preferred over binocular PD because it accounts for what?

• a.Lens tint
• b.Segment width
• c.Facial asymmetry between the two eyes✓
• d.Frame color

Monocular PD measures each eye separately from the bridge center, correctly placing each optical center even when the face is asymmetric, which a single binocular PD split in half cannot do.

High-minus lenses can be made cosmetically thinner at the edge by doing what?

• a.Adding pantoscopic tilt
• b.Using a higher-index material and edge treatments like a roll and polish✓
• c.Choosing a larger frame
• d.Increasing the base curve

Higher-index materials reduce edge thickness for minus lenses, and a smaller frame plus proper decentration further reduces thickness. Rolling and polishing the edge improves the cosmetic appearance.

For a high-plus (aphakic-type) lens, choosing a smaller frame does what?

• a.Makes the lens heavier
• b.Adds prism
• c.Reduces center thickness and weight✓
• d.Increases center thickness

A smaller eye size means less lens material, reducing the thick center of a high-plus lens and lowering weight while improving cosmetics. Frame choice is a key tool for plus-lens patients.

When fitting a progressive lens, accurate fitting-cross placement is critical because what?

• a.It changes the base curve only
• b.It changes the frame color
• c.Misplacement forces the wearer to adopt awkward head postures✓
• d.It changes the tint

The fitting cross must align with the pupil in primary gaze; if it is off, the corridor and reading zone are misplaced, forcing the patient to tilt or turn the head to find clear vision.

A patient complains of temple pain behind the ears with new glasses. The best adjustment is to do what?

• a.Adjust the temple bend and length so it rests without pressure✓
• b.Add nose pads
• c.Tighten the temples further
• d.Increase wrap

Pain behind the ear usually means the temple bend starts too early or presses too hard; lengthening or repositioning the bend so it follows the ear contour relieves the pressure point.

Wrap angle (face-form) that is too aggressive on a high-powered Rx can cause what?

• a.No optical effect
• b.Better peripheral vision
• c.Lighter weight
• d.Unwanted prism and blur unless the lens is compensated✓

Excess wrap tilts the lens relative to the line of sight, inducing unwanted cylinder and prism, especially in stronger prescriptions. Compensated (wrap) lens designs correct for this tilt.

Which patient complaint most suggests the PD was measured or set too wide?

• a.Frame slides down
• b.Seg too low
• c.Temples too tight
• d.Eyestrain with a feeling of eyes being pulled outward✓

An overly wide PD places the optical centers outside the pupils, inducing base-out prism that the eyes must overcome, often felt as eyestrain or an outward pulling sensation.

A photochromic lens is a poor choice for a patient who wants dark lenses primarily where?

• a.Outdoors on a sunny day
• b.At the beach
• c.Inside a car (windshield blocks UV)✓
• d.In the snow

Because most photochromics activate with UV, and car windshields block much of the UV, the lenses stay relatively light while driving. A polarized or fixed-tint sunglass better serves in-car darkening.

Anti-reflective coating is especially recommended for which patients?

• a.Night drivers and computer users bothered by glare✓
• b.Those wanting a mirror tint
• c.Only safety-eyewear wearers
• d.Only children

AR coating cuts reflections and glare, benefiting night drivers who see haloes around lights and computer users bothered by screen and overhead reflections, improving both comfort and clarity.

To fit a frame that is too tight and leaves marks on the temples, the optician should do what?

• a.Widen the temple spread or adjust the endpieces outward✓
• b.Shorten the temples
• c.Increase the base curve
• d.Add pantoscopic tilt

When a frame grips the sides of the head too tightly, spreading the temples or adjusting the endpieces outward increases the temple width and relieves the pressure marks on the head.

A patient with a strong Rx wants the thinnest possible lens. Besides high-index material, what frame choice helps most?

• a.A small, well-centered frame matching their PD✓
• b.A thick plastic frame
• c.A large aviator
• d.A rimless mount only

A smaller frame that closely matches the patient's PD minimizes decentration and the amount of lens outside the optical center, reducing both edge thickness (minus) and center thickness (plus).

For a progressive lens, insufficient seg/fitting height (frame too shallow) causes what problem?

• a.Too much add power
• b.Not enough room for the reading zone, cutting off near vision✓
• c.Distance blur
• d.Excess prism

Progressive corridors need adequate vertical depth; if the frame's B measurement is too small, the reading portion at the bottom is cut off, leaving the wearer with inadequate near vision.

When dispensing polycarbonate, which coating is nearly always added and why?

• a.A mirror coat for style
• b.A polarized film
• c.A photochromic dye
• d.A scratch-resistant (hard) coating because polycarbonate is soft✓

Polycarbonate has a soft surface that scratches easily, so manufacturers apply a scratch-resistant hard coating to protect it. AR is also commonly added for its otherwise reflective surface.

A patient reports objects appear tilted or the floor seems to slope with new glasses that have significant cylinder. This is most likely due to what?

• a.Adaptation to new or changed cylinder axis/power✓
• b.Loose temples
• c.Wrong tint
• d.A scratched lens

Changes in cylinder power or axis alter spatial perception, and patients often notice tilting, sloping floors, or a fishbowl effect until they neurologically adapt, usually within a couple of weeks.

The vertical position for a general-wear D-segment bifocal is typically set at what landmark?

• a.The center of the pupil
• b.The eyebrow
• c.The top of the frame
• d.The lower eyelid margin (lower limbus)✓

A conventional flat-top (D) bifocal seg is usually set at the lower eyelid margin or lower limbus so it is out of the distance line of sight but reachable with a slight downward gaze.

Which combination is generally problematic when dispensing?

• a.A very high-plus lens in a large, rimless drill-mount frame✓
• b.Photochromic in a full-rim frame
• c.Polycarbonate in a safety frame
• d.AR coating on a plastic lens

A very high-plus lens has thick, heavy edges poorly suited to a large rimless drill mount, which stresses the lens at drill points and looks bulky; a smaller full-rim frame is more appropriate.

To reduce a patient's eyes appearing magnified in a high-plus lens, the optician can recommend what?

• a.An aspheric high-index lens✓
• b.A larger frame
• c.A thicker lens
• d.More pantoscopic tilt

Aspheric high-index designs flatten the lens and reduce magnification and bulge, minimizing the enlarged-eye appearance typical of high-plus lenses while keeping the lens thinner and lighter.

When adjusting metal nose pads to raise a frame on the face, the pads should be moved how?

• a.Farther apart
• b.Angled outward
• c.Closer together✓
• d.Left unchanged

Bringing the nose pads closer together makes them rest on a narrower part of the nose, which raises the frame higher on the face. Spreading them apart lowers the frame.

A patient's frame keeps sliding down despite tight nose pads. Besides the pads, which adjustment can help retention?

• a.Increase the base curve
• b.Loosen the endpieces
• c.Adjust the temple bend so it grips gently behind the ears✓
• d.Add more add power

Retention comes from both the nose and the ears; adjusting the temple bend so it curves gently behind and around the ear adds holding power. Combined with proper nose-pad fit, this stops a frame from sliding down.

A lensmeter (focimeter) is used to measure what?

• a.Corneal curvature
• b.Pupillary distance
• c.The power, axis, add, and optical center of a lens✓
• d.Frame temple length

The lensmeter reads a lens's sphere and cylinder power, cylinder axis, add power, optical center location, and any prism. It is the primary verification instrument in an optical lab and dispensary.

A pupillometer is designed to measure what?

• a.Base curve
• b.Lens power
• c.Monocular and binocular pupillary distance✓
• d.Segment height

A pupillometer measures the distance between the pupils, providing accurate monocular and binocular PD readings and can be set for distance or near, improving accuracy over a simple PD ruler.

Under FDA regulations, all dress eyewear lenses sold in the United States must be what?

• a.Impact resistant (capable of passing the drop-ball test)✓
• b.Made of glass
• c.Tinted
• d.Polarized

The FDA requires prescription and non-prescription dress lenses to be impact resistant, historically demonstrated by the drop-ball test, to protect wearers from lens shattering into the eye.FDA impact resistance

The FDA drop-ball test for impact resistance drops what onto the lens?

• a.A metal rod
• b.A rubber mallet
• c.A 5/8-inch steel ball from 50 inches✓
• d.A hammer

The drop-ball test drops a 5/8-inch (15.9 mm) steel ball weighing about 16 grams from a height of 50 inches onto the lens; the lens must not fracture to demonstrate impact resistance.FDA impact resistance

ANSI Z80.1 is the American National Standard that specifies what?

• a.Tolerances and requirements for prescription ophthalmic (dress) lenses✓
• b.Frame color standards
• c.Building fire codes
• d.Contact lens solutions

ANSI Z80.1 sets the recommended tolerances and requirements for prescription dress eyewear, including allowable deviations in power, cylinder axis, add, prism, and marking, guiding lens verification.ANSI Z80

Occupational and safety eyewear in the U.S. is governed by which standard?

• a.ANSI Z87.1✓
• b.ANSI Z80.1
• c.HIPAA
• d.FDA drop-ball only

ANSI Z87.1 sets requirements for occupational and educational personal eye protection, specifying high-impact testing and markings. Dress eyewear follows ANSI Z80.1, a different, less stringent impact standard.ANSI Z80

Safety frames and lenses that meet the high-impact standard are marked with what?

• a.Z87+ (the plus indicating high impact)✓
• b.FDA
• c.AR
• d.Z80

Under ANSI Z87.1, high-impact-rated safety eyewear is marked 'Z87+', where the plus sign denotes passing the high-velocity and high-mass impact tests; basic-impact eyewear is marked 'Z87' without the plus.ANSI Z80

Under HIPAA, a patient's prescription and health information must be handled how?

• a.Discarded openly
• b.Posted publicly
• c.Kept private and disclosed only as permitted✓
• d.Shared with any vendor

HIPAA requires that protected health information, including a patient's optical prescription and records, be kept confidential and disclosed only to authorized parties or as the patient permits.HIPAA

A distometer is used to measure what?

• a.Frame width
• b.Vertex distance from the cornea to the back of the lens✓
• c.Pupillary distance
• d.Lens power

A distometer measures the vertex distance between the front of the eye and the back surface of the lens, information needed for accurate power compensation in higher prescriptions.

Professional ethics require an optician who discovers a possible prescription error to do what?

• a.Refuse all service
• b.Fill it as written without comment
• c.Change the Rx independently
• d.Verify with the prescriber before dispensing✓

Ethical and safe practice requires the optician to confirm a questionable or seemingly erroneous prescription with the prescribing doctor rather than guessing or unilaterally altering it, protecting the patient.

A Geneva lens clock (lens measure) reads what?

• a.Pupillary distance
• b.Lens power in the eye
• c.Surface curvature (base curve) of a lens✓
• d.Prism amount

A lens clock, or Geneva lens measure, uses three pins to measure the sag of a lens surface and reports the surface curve in diopters, commonly used to check base curve and detect warpage.

When cleaning and handling patient frames and instruments, an optician maintains professionalism by doing what?

• a.Following sanitation and equipment-calibration routines✓
• b.Ignoring hygiene
• c.Reusing dirty cloths
• d.Skipping calibration

Regular sanitation of tools and frames and periodic calibration of instruments such as the lensmeter and pupillometer ensure accurate measurements and hygienic, professional service to patients.

Using Prentice's rule, how much prism is induced when a +4.00 D lens is decentered 5 mm?

• a.1.0 prism diopter
• b.0.5 prism diopters
• c.2.0 prism diopters✓
• d.20 prism diopters

Prentice's rule: prism (prism diopters) = decentration (cm) x power (D). 5 mm = 0.5 cm; 0.5 x 4.00 = 2.0 prism diopters.

A -6.00 D lens must produce 3 prism diopters. How far must it be decentered (Prentice's rule)?

• a.18 cm
• b.3 cm
• c.0.5 cm (5 mm)✓
• d.6 cm

Decentration = prism / power = 3 / 6.00 = 0.5 cm, which equals 5 mm of decentration from the optical center.

Transpose -1.75 +1.25 x 060 to minus-cylinder form.

• a.-0.50 +1.25 x 150
• b.-1.75 -1.25 x 060
• c.-3.00 -1.25 x 060
• d.-0.50 -1.25 x 150✓

New sphere = -1.75 + 1.25 = -0.50; change cylinder sign to -1.25; rotate axis 90 degrees (060 to 150). Result: -0.50 -1.25 x 150.

A frame has an A measurement of 52 mm, DBL of 18 mm, and the patient's PD is 62 mm. What is the total decentration for both lenses combined?

• a.8 mm total (4 mm per lens)✓
• b.0 mm
• c.16 mm per lens
• d.8 mm per lens

Frame PD (geometric center distance) = A + DBL = 52 + 18 = 70 mm. Total decentration = frame PD - patient PD = 70 - 62 = 8 mm total, split as 4 mm per lens.

With a 34 mm effective diameter and 4 mm per-lens decentration, what is the approximate minimum blank size?

• a.34 mm
• b.About 42 mm✓
• c.30 mm
• d.52 mm

A common working rule for minimum blank size is effective diameter + (2 x per-lens decentration). 34 + (2 x 4) = 42 mm, before adding any small manufacturing tolerance.

A patient is refracted at a 12 mm vertex with -10.00 D, but the frame sits at 16 mm. Which way does the effective power change, requiring compensation?

• a.No change occurs
• b.It becomes plus power
• c.Toward more minus, so less minus is ordered
• d.The lens must gain minus power✓

Moving a minus lens farther from the eye (12 to 16 mm) increases its effective minus power, so a slightly weaker (less minus) lens is ordered to keep the correction accurate at the new vertex distance.

What is the combined horizontal prism when the right lens gives 2 prism diopters base out and the left lens gives 1 prism diopter base out?

• a.3 prism diopters base out total✓
• b.0 prism diopters
• c.1 prism diopter base out total
• d.2 prism diopters base in

Horizontal prisms of the same base direction in the two eyes add together. 2 base out + 1 base out = 3 prism diopters base out total split across the two eyes.

Compute the spherical equivalent of +3.00 -2.00 x 090.

• a.+5.00 D
• b.+2.00 D✓
• c.+4.00 D
• d.+1.00 D

Spherical equivalent = sphere + (cylinder / 2) = +3.00 + (-2.00 / 2) = +3.00 + (-1.00) = +2.00 D.

How much vertical prism imbalance exists if the reading point is 8 mm below the OC in a +2.50 D right lens and a +1.00 D left lens (Prentice's rule)?

• a.0.8 prism diopters
• b.0 prism diopters
• c.1.2 prism diopters✓
• d.3.5 prism diopters

Each eye's prism = 0.8 cm x power. Right = 0.8 x 2.50 = 2.0; left = 0.8 x 1.00 = 0.8. Both are base-down (plus lens, below OC), so the imbalance = 2.0 - 0.8 = 1.2 prism diopters.

A lens has a front curve of +8.00 D and needs +2.00 D total power. What back curve is required (thin-lens approximation)?

• a.+6.00 D
• b.+10.00 D
• c.-6.00 D✓
• d.-2.00 D

Total power = front + back. Back = total - front = +2.00 - (+8.00) = -6.00 D. The back surface must be ground to -6.00 D to achieve the +2.00 D lens.