CSLB General Building (B) — All Questions

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

• a.10 cm
• b.25 cm
• c.50 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.+4.00 D✓
• c.+0.25 D
• d.+25.00 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.Slow down and bend toward the normal✓
• b.Speed up and bend away from the normal
• c.Continue at the same speed
• d.Stop completely

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.Polycarbonate
• b.1.67 high-index
• c.CR-39 (1.498)✓
• 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.Real image, real focal point
• b.Virtual image, virtual focal point✓
• c.Real image, virtual focal point
• d.No image at all

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.Increases (flatter surface)
• b.Stays the same
• c.Decreases (steeper 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.+4.00 D✓
• b.+8.00 D
• c.-4.00 D
• d.+3.00 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 color wavelength
• b.Its polarization angle
• c.Its intensity
• 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 reference curve from which the lens is made, usually the front✓
• c.The segment line
• d.The temple curve

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 distance sphere power
• b.The prism amount
• 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.-1.00 D✓
• b.-5.00 D
• c.+2.00 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 two pupils
• b.The back of the lens and the front of the cornea✓
• c.The frame front and the temple
• 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.Uneven frame pressure
• b.Scratches on the lens
• c.Different wavelengths of light focusing at different points✓
• 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 high minus lens
• c.A lens with cylinder only
• d.A lens with no refractive power✓

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.Peripheral rays focusing differently than central rays✓
• c.Reflection off both surfaces
• d.Distortion from prism

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.Front curve to back curve
• c.Diameter to thickness
• d.Weight to volume

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

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

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.Reflection intensity
• b.Polarization
• 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.Thinner✓
• b.Thicker
• c.Softer
• d.More curved

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

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 mm at 1 meter
• b.1 cm at 1 meter✓
• c.1 m 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 flat surface
• b.A concave surface
• c.A prism surface
• d.A convex 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.Plano lenses
• c.Low-powered lenses
• d.Cylinder-only 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.Maximum prism occurs
• b.The cylinder axis crosses
• c.Light passes with no prismatic deviation✓
• d.The bevel is thickest

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.Temperature only
• d.Polarized reflections

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

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.Direct overhead sunlight only
• c.Indoor fluorescent light
• d.Digital device blue light

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

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.Astigmatism✓
• c.Simple myopia
• d.Color blindness

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

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.-3.00 -2.00 x 045
• b.-5.00 +2.00 x 135
• c.-1.00 -2.00 x 135✓
• d.-1.00 +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 axis of the cylinder✓
• c.The add power
• d.The prism base

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.Double segment
• b.Distance seg
• c.Decentration standard
• 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.An allowed tolerance range of the prescribed power✓
• b.Exactly the prescribed power with zero deviation
• c.Half the prescribed power
• d.Twice 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.1.0 prism diopter
• b.2.0 prism diopters✓
• c.5.0 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 axis
• c.The add✓
• 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 vertical distance from the lowest point of the lens to the top of the segment line✓
• b.The horizontal distance between segments
• c.The width of the bifocal
• d.The pantoscopic tilt

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

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.60 to 62 mm✓
• c.64 mm exactly
• d.70 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.Frame color
• b.Lens tint
• c.Vertex distance and lens tilt✓
• d.Bridge size

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.Increases (more minus effect)
• c.Stays exactly the same
• 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 bevel apex
• b.The point where the target is clear with no prism, the optical center✓
• c.The segment top
• d.The frame temple

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

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 45
• b.Axis 135
• c.Axis 90 in plus cylinder
• d.Axis 180 in minus 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 -0.50 x 090✓
• b.+1.50 -0.50 x 090
• c.+2.25 -0.50 x 090
• d.+3.75 -2.75 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.Vertical alignment
• b.Convergence or divergence problems (horizontal)✓
• c.Reading add
• 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.0.67 cm up
• b.3.0 cm down
• c.1.5 cm (raise the OC 15 mm)✓
• d.6.0 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.Vertical imbalance at near between the two eyes✓
• b.Horizontal PD error
• c.Excess add power
• d.A scratched segment

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

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 frame PD
• b.The refracted vertex distance✓
• c.The seg height
• 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.-2.50 D✓
• b.-3.00 D
• c.-1.50 D
• d.-2.00 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.Temporally (outward)
• b.Vertically only
• c.Nasally (inward)✓
• 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 up
• b.Base down
• c.Base in
• d.Base out✓

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

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

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

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

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.Lower the segment height in a remake or raise the frame✓
• b.Raise the segment
• c.Add more add power
• 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.Facial asymmetry between the two eyes✓
• c.Frame color
• d.Segment width

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

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

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

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.Tighten the temples further
• b.Adjust the temple bend and length so it rests without pressure✓
• c.Add nose pads
• 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.Better peripheral vision
• b.No optical effect
• c.Unwanted prism and blur unless the lens is compensated✓
• d.Lighter weight

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

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

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

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 large aviator
• c.A rimless mount only
• d.A thick plastic frame

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

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 scratch-resistant (hard) coating because polycarbonate is soft✓
• c.A polarized film
• d.A photochromic dye

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

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

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

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

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.Left unchanged
• d.Closer together✓

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

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

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

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.Made of glass
• b.Tinted
• c.Impact resistant (capable of passing the drop-ball test)✓
• 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 rubber mallet
• b.A metal rod
• c.A hammer
• d.A 5/8-inch steel ball from 50 inches✓

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.Building fire codes
• c.Contact lens solutions
• d.Frame color standards

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

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

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

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

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

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.Lens power in the eye
• b.Pupillary distance
• 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.Ignoring hygiene
• b.Reusing dirty cloths
• c.Skipping calibration
• d.Following sanitation and equipment-calibration routines✓

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.2.0 prism diopters✓
• c.20 prism diopters
• d.0.5 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.0.5 cm (5 mm)✓
• b.3 cm
• c.18 cm
• 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.-1.75 -1.25 x 060
• b.-3.00 -1.25 x 060
• c.-0.50 -1.25 x 150✓
• 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 per lens
• b.0 mm
• c.16 mm per lens
• d.8 mm total (4 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.About 42 mm✓
• b.34 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.Toward more minus, so less minus is ordered
• b.The lens must gain minus power✓
• c.No change occurs
• d.It becomes plus 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.1 prism diopter base out total
• b.2 prism diopters base in
• c.3 prism diopters base out total✓
• d.0 prism diopters

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.+2.00 D✓
• b.+1.00 D
• c.+4.00 D
• d.+5.00 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 prism diopters
• b.3.5 prism diopters
• c.0.8 prism diopters
• d.1.2 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.-6.00 D✓
• c.+10.00 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.