ABO Basic Optician Certification Exam — Questions and Answers

Question 1: What does a myopic patient experience without corrective lenses?

Blurred distance vision (Correct answer)
Double vision at all distances
Color blindness
Blurred near vision

Correct answer: Blurred distance vision

Myopia (nearsightedness) causes light to focus in front of the retina, making distant objects appear blurry while near vision remains clear.

Question 2: Which contact lens parameter describes the amount of lens material per unit area of lens surface?

Center thickness
Dk value
Dk/t (oxygen transmissibility) (Correct answer)
Water content

Correct answer: Dk/t (oxygen transmissibility)

Dk/t (oxygen transmissibility) accounts for the lens Dk divided by its thickness (t), reflecting actual oxygen passage through the specific lens as worn.

Question 3: Which base curve selection guideline applies when fitting rigid gas-permeable (RGP) contact lenses?

Fit 0.50 D steeper than flat K
Align the lens base curve with the flattest K (Correct answer)
Match base curve to the average of both K readings
Fit 1.00 D flatter than steep K

Correct answer: Align the lens base curve with the flattest K

The standard RGP fitting philosophy is to align the lens base curve with the flattest keratometry reading to achieve an 'on K' or alignment fit.

Question 4: Measuring the near point of convergence (NPC) is performed primarily to evaluate:

Stereoacuity threshold in arc seconds
Distance visual acuity
The maximum convergence ability of the eyes (Correct answer)
Vergence facility at different spatial frequencies

Correct answer: The maximum convergence ability of the eyes

The NPC test determines the closest point at which a patient can maintain single binocular vision by converging, directly reflecting maximum convergence amplitude.

Question 5: What does the term 'emmetropia' describe?

An eye with astigmatism
An eye with myopia
An eye with hyperopia
An eye with no refractive error (Correct answer)

Correct answer: An eye with no refractive error

Emmetropia describes the ideal refractive state where parallel light rays focus precisely on the retina without any corrective lens.

Question 6: A patient's prescription reads +2.50 -1.00 x 090. What is the power in the 180° meridian?

+3.50 D
+2.50 D
-1.00 D
+1.50 D (Correct answer)

Correct answer: +1.50 D

At 180°, the cylinder has no effect, so the power is the sphere (+2.50) plus the cylinder component at that meridian; the 90° axis means full cylinder effect at 180°, giving +2.50 + (-1.00) = +1.50 D.

Question 7: What is the recommended minimum central corneal clearance (vault) when fitting a scleral contact lens?

200–400 microns (Correct answer)
50–100 microns
500–600 microns
100–200 microns

Correct answer: 200–400 microns

A minimum central clearance of approximately 200 microns (some guidelines say 200–400 µm) is recommended at dispensing to account for settling over the wear period.

Question 8: Anisometropic amblyopia develops primarily because:

A significant refractive difference between the two eyes causes chronic blur in one eye (Correct answer)
A constant unilateral strabismus suppresses one eye
Congenital media opacity prevents form vision
Ptosis occludes the visual axis

Correct answer: A significant refractive difference between the two eyes causes chronic blur in one eye

A large interocular refractive difference results in one eye receiving a chronically defocused image, leading to cortical suppression and amblyopia despite proper alignment.

Question 9: Topical NSAIDs (e.g., ketorolac, bromfenac) are used in ophthalmic practice primarily for:

Managing pain and inflammation after cataract surgery (Correct answer)
Treating bacterial infections
Reversing pharmacological mydriasis
Lowering intraocular pressure

Correct answer: Managing pain and inflammation after cataract surgery

Topical NSAIDs inhibit prostaglandin synthesis to control postoperative pain, photophobia, and inflammation without the risks of steroid-induced cataract or IOP elevation.

Question 10: Which condition is characterized by a refractive error caused by increased axial length without any change in corneal or lenticular power?

Refractive myopia
Axial myopia (Correct answer)
Curvature myopia
Index myopia

Correct answer: Axial myopia

Axial myopia results specifically from an elongated globe, placing the retina behind the focal point of the optical system.

Question 11: Which organization publishes the ANSI Z80 series of ophthalmic standards in the United States?

The American National Standards Institute (Correct answer)
The Vision Council of America
The American Optometric Association
The FDA Center for Devices and Radiological Health

Correct answer: The American National Standards Institute

ANSI (American National Standards Institute) publishes and maintains the Z80 series, which includes standards for ophthalmic lenses, frames, and instruments.

Question 12: Which lens type is most effective at reducing oblique astigmatic error for off-axis gaze?

Flat-front lens
Biconcave lens
Plano lens
Corrected curve (best form) lens (Correct answer)

Correct answer: Corrected curve (best form) lens

Corrected curve (best form) lenses are designed with base curves that minimize oblique astigmatism during off-axis viewing.

Question 13: A patient's spectacle Rx is -4.00 -2.00 x 180. Using the spherical equivalent, what power soft contact lens would you initially trial?

-6.00 D
-4.00 D
-3.00 D
-5.00 D (Correct answer)

Correct answer: -5.00 D

Spherical equivalent = sphere + (cylinder/2) = -4.00 + (-2.00/2) = -4.00 + (-1.00) = -5.00 D.

Question 14: What is the primary advantage of silicone hydrogel contact lenses over conventional hydrogel lenses?

Superior protein deposit resistance
Significantly higher oxygen transmissibility (Dk/t) (Correct answer)
Greater water content
Better UV protection

Correct answer: Significantly higher oxygen transmissibility (Dk/t)

Silicone hydrogel lenses have dramatically higher Dk/t values due to silicone's high oxygen permeability, reducing hypoxia-related complications.

Question 15: Which layer of the retina contains the cell bodies of bipolar cells?

Ganglion cell layer
Outer nuclear layer
Inner plexiform layer
Inner nuclear layer (Correct answer)

Correct answer: Inner nuclear layer

The inner nuclear layer contains the cell bodies of bipolar, horizontal, amacrine, and Müller cells.

Question 16: Which structure connects the ciliary body to the lens and is responsible for maintaining lens shape during accommodation?

Vitreous cortex
Hyaloid membrane
Zonules of Zinn (zonular fibers) (Correct answer)
Anterior hyaloid face

Correct answer: Zonules of Zinn (zonular fibers)

The zonules of Zinn (zonular fibers) connect the ciliary body to the lens capsule and transmit ciliary muscle forces to change lens shape during accommodation.

Question 17: Slab-off (bicentric grinding) is most commonly used to correct:

Vertical imbalance at the near zone in high anisometropic prescriptions (Correct answer)
Horizontal phorias in single vision lenses
Progressive lens corridor swim
Chromatic aberration in high-index lenses

Correct answer: Vertical imbalance at the near zone in high anisometropic prescriptions

Slab-off creates a prism difference at the near zone to compensate for the vertical prismatic imbalance caused by anisometropia when reading through bifocals.

Question 18: Which retinal cell type is primarily responsible for initiating the phototransduction cascade in dim light (scotopic vision)?

Rod photoreceptors (Correct answer)
S-cones (short-wavelength cones)
Intrinsically photosensitive retinal ganglion cells (ipRGCs)
M-cones (medium-wavelength cones)

Correct answer: Rod photoreceptors

Rod photoreceptors contain rhodopsin and are exquisitely sensitive to low light levels, mediating scotopic (dim light) vision.

Question 19: The ora serrata is clinically significant because it marks the:

Boundary between the pigmented and non-pigmented ciliary epithelium
Posterior limit of the vitreous base
Junction of the optic nerve and retina
Anterior termination of the neurosensory retina (Correct answer)

Correct answer: Anterior termination of the neurosensory retina

The ora serrata is the anterior boundary of the neurosensory (photoreceptor-containing) retina, where it transitions to the non-photoreceptive pars plana.

Question 20: What is the vergence formula used to find image vergence after a lens?

L' = L + F (Correct answer)
L' = L - F
L' = F - L
L' = L × F

Correct answer: L' = L + F

The vergence formula states that image vergence equals object vergence plus lens power.

Question 21: The Maddox rod test is used clinically to measure:

Accommodative amplitude
Anisometropia
Heterophoria and vergence deviation (Correct answer)
The amount of astigmatism

Correct answer: Heterophoria and vergence deviation

The Maddox rod converts a point source into a streak, dissociating the eyes to reveal and measure phoria or tropia.

Question 22: A patient wearing silicone hydrogel lenses develops superior epithelial arcuate lesions (SEALs). The most appropriate initial management is:

Discontinue lens wear permanently
Switch to a thicker, higher-Dk lens
Refit with a flatter base curve or thinner lens (Correct answer)
Prescribe topical steroids immediately

Correct answer: Refit with a flatter base curve or thinner lens

SEALs are caused by mechanical trauma from a stiff lens edge; refitting with a flatter base curve or thinner lens reduces this mechanical effect.

Question 23: A Fresnel prism is most accurately described as:

A thin, lightweight press-on prism made of concentric prismatic rings (Correct answer)
A type of progressive lens design
A permanently ground prism on the back surface of the lens
A prism used only in sunglasses

Correct answer: A thin, lightweight press-on prism made of concentric prismatic rings

A Fresnel prism is a thin plastic press-on membrane with concentric prismatic grooves that approximates the effect of a full glass prism with minimal weight and thickness.

Question 24: The cornea receives its sensory innervation from which nerve?

Facial nerve (CN VII)
Oculomotor nerve (CN III)
Nasociliary branch of CN V1 (Correct answer)
Maxillary branch of CN V2

Correct answer: Nasociliary branch of CN V1

The cornea is innervated by the nasociliary branch of the ophthalmic division (V1) of the trigeminal nerve via the long ciliary nerves.

Question 25: In frame adjustment, the 'face-form angle' (wrap) primarily affects which aspect of the fit?

Pantoscopic tilt
Vertex distance
Temple length
The degree to which the frame curves to follow the face (Correct answer)

Correct answer: The degree to which the frame curves to follow the face

Face-form angle (wrap) describes how much the frame front curves horizontally to follow the contour of the face.

Question 26: A patient's single vision lenses show prismatic displacement of images. Which instrument is used to measure this induced prism?

Geneva lens clock
Keratometer
Lensometer (lensmeter) (Correct answer)
Pupillometer

Correct answer: Lensometer (lensmeter)

The lensometer (focimeter) is used to measure lens power and to quantify prismatic effect by locating the optical center relative to the pupil position.

Question 27: A patient whose exophoria is significantly greater at distance than at near most likely has which binocular vision condition?

Convergence insufficiency
Divergence excess (or simulated divergence excess) (Correct answer)
Basic exophoria
Convergence excess

Correct answer: Divergence excess (or simulated divergence excess)

When an exodeviation is substantially larger at distance than at near, the clinical classification is divergence excess, reflecting an inability to maintain adequate fusional divergence at far.

Question 28: Which of the following best describes 'prism thinning' in lens fabrication?

Using a prism to measure lens power
Adding base-up prism to flatten a lens
Grinding the lens to a uniform thickness
Decentering the lens blank to reduce edge thickness on one side (Correct answer)

Correct answer: Decentering the lens blank to reduce edge thickness on one side

Prism thinning involves decentering the lens blank so that unwanted prism thins down the thicker edge of high-power lenses.

Question 29: A higher Abbe value (V-number) in a lens material indicates:

Greater impact resistance
Better UV protection
Less chromatic aberration (Correct answer)
Higher refractive index

Correct answer: Less chromatic aberration

A higher Abbe value means less dispersion of light into its component colors, resulting in less chromatic aberration.

Question 30: Where are the cone photoreceptors most densely concentrated?

Ora serrata
Optic disc
Fovea (Correct answer)
Peripheral retina

Correct answer: Fovea

The fovea contains the highest concentration of cone photoreceptors and is responsible for sharp central vision and color perception.

Question 31: Which topical anesthetic is most commonly used during ophthalmic procedures such as tonometry and foreign body removal?

Benzocaine
Injectable lidocaine
Proparacaine (Correct answer)
Oral tetracaine

Correct answer: Proparacaine

Proparacaine is the most widely used topical ophthalmic anesthetic, providing rapid corneal and conjunctival anesthesia without injection.

Question 32: Which frame measurement represents the distance between the two lenses at their closest point?

DBL (distance between lenses) (Correct answer)
ED (effective diameter)
A measurement
Frame PD

Correct answer: DBL (distance between lenses)

DBL (distance between lenses) is the bridge measurement representing the narrowest gap between the two lenses.

Question 33: Progressive addition lenses typically have an unwanted astigmatism zone located:

In the intermediate corridor
In the distance zone
In the lateral peripheral areas (Correct answer)
In the near zone

Correct answer: In the lateral peripheral areas

Unwanted (peripheral) astigmatism in PALs is concentrated in the lateral areas on either side of the progressive corridor.

Question 34: The lacrimal gland produces the aqueous component of the tear film. Its secretory activity is stimulated primarily by:

Parasympathetic fibers from the facial nerve (CN VII) (Correct answer)
Sympathetic fibers from the superior cervical ganglion
Sensory fibers from the trigeminal nerve (CN V1)
Somatic motor fibers from CN III

Correct answer: Parasympathetic fibers from the facial nerve (CN VII)

Parasympathetic fibers traveling with the facial nerve (CN VII) via the pterygopalatine ganglion stimulate lacrimal gland secretion.

Question 35: Corneal topography showing an asymmetric bow-tie pattern with skewed radial axes (SRAX) is most suggestive of:

Keratoconus (Correct answer)
Post-refractive surgery ectasia
Pellucid marginal degeneration
Regular corneal astigmatism

Correct answer: Keratoconus

SRAX on corneal topography, where the bow-tie axes are not aligned, is a hallmark early sign of keratoconus.

Question 36: Which measurement is used to set the height of the progressive lens fitting cross on the patient's face?

Vertex distance
DBL
Monocular PD
Segment height (fitting height) (Correct answer)

Correct answer: Segment height (fitting height)

The fitting height (measured from the bottom of the frame to the pupil center) is used to position the progressive lens fitting cross at the pupil level.

Question 37: The Worth 4-Dot test uses red and green filters to evaluate:

The full refractive error of each eye
Suppression and the quality of binocular fusion (Correct answer)
Stereoacuity in arc seconds
Accommodation amplitude

Correct answer: Suppression and the quality of binocular fusion

By presenting red dots only to one eye and green dots only to the other, the Worth 4-Dot test reveals whether the patient is fusing, suppressing one eye, or experiencing diplopia.

Question 38: The vitreous humor is attached most firmly to the retina at which location?

Posterior pole near the fovea
Optic nerve head only
Vitreous base straddling the ora serrata (Correct answer)
Equator of the globe

Correct answer: Vitreous base straddling the ora serrata

The vitreous base, which straddles the ora serrata, is the site of the firmest vitreoretinal attachment and does not detach even in advanced PVD.

Question 39: A patient with HIV and CD4 count <50 cells/µL presents with painless progressive peripheral visual field loss and 'pizza pie' fundus appearance. The most likely diagnosis is:

Acute retinal necrosis
Progressive outer retinal necrosis
Toxoplasma retinochoroiditis
CMV retinitis (Correct answer)

Correct answer: CMV retinitis

CMV retinitis classically produces hemorrhagic, necrotizing retinitis with a 'pizza pie' or 'cottage cheese and ketchup' fundus in severely immunocompromised HIV patients.

Question 40: The ABO Code of Ethics requires opticians to represent their qualifications honestly. This means an optician should NOT:

Display state licensure credentials at the dispensary
Claim to hold an NCLE certification without having earned it (Correct answer)
Inform patients of the difference between an optician and an optometrist
List ABO certification on business cards

Correct answer: Claim to hold an NCLE certification without having earned it

Falsely claiming credentials such as NCLE certification violates the ABO Code of Ethics and professional honesty standards.

Question 41: Clinically normal stereoacuity is typically defined as a threshold of:

40 arc seconds or better (Correct answer)
1,000 arc seconds
500 arc seconds
100–200 arc seconds

Correct answer: 40 arc seconds or better

A stereoacuity of 40 arc seconds or better (on tests such as the Randot or Titmus) is considered within normal limits for bifoveal stereopsis.

Question 42: The optical center of a spectacle lens is defined as the point:

Of maximum surface curvature
Where no prismatic effect is induced (Correct answer)
Where light refracts most strongly
Of maximum lens thickness

Correct answer: Where no prismatic effect is induced

At the optical center, a ray passes through the lens without prismatic deviation, making centering critical for patient comfort.

Question 43: "Simultaneous vision" for presbyopia patients wearing multifocal contact lenses means:

The need to physically move the eyes to switch between near and far vision
The ability to see near and far objects clearly but not at intermediate distances
The eye receiving images from both near and distance zones at the same time (Correct answer)
Sequential focusing on near and distant objects, requiring adjustment time

Correct answer: The eye receiving images from both near and distance zones at the same time

The feature of multifocal contact lenses known as "simultaneous vision" refers to the ability of the wearer's eye to simultaneously receive images from the near and far zones. Depending on the viewing distance, the brain then chooses the clearest image, enabling continuous vision at various ranges without the need for manual correction.

Question 44: In retinoscopy, a 'with' motion of the reflex indicates what type of refractive error?

Emmetropia
Hyperopia or insufficient minus correction (Correct answer)
Myopia beyond the working distance
Astigmatism only

Correct answer: Hyperopia or insufficient minus correction

A 'with' motion during retinoscopy indicates that the eye is hyperopic or has insufficient minus power, requiring additional plus power to reach neutralization.

Question 45: Which of the following is MOST important for astigmatic patients receiving toric soft contact lens fittings in order to ensure good visual acuity?

The diameter of the lens
The water content of the lens
The stabilization mechanism of the lens (Correct answer)
The base curve of the lens

Correct answer: The stabilization mechanism of the lens

For astigmatic patients, the stabilizing mechanism of toric soft contact lenses is essential to achieving the best possible isual acuity. By maintaining the lens's right orientation on the eye, this mechanism makes sure that the astigmatic correction appropriately matches the astigmatism of the eye.

Question 46: The Jackson cross cylinder (JCC) is used to refine which components of the refraction?

Add power and base curve
Sphere, cylinder, and axis
Sphere power only
Cylinder power and axis only (Correct answer)

Correct answer: Cylinder power and axis only

The JCC is specifically designed to refine the cylindrical axis and power without changing the spherical equivalent.

Question 47: What is the primary difference between ABO certification and state licensure for opticians?

ABO certification supersedes the need for state licensure
State licensure is a legal requirement set by each state; ABO certification is a voluntary national credential (Correct answer)
ABO certification is legally required in all 50 states
State licensure is issued by the ABO organization

Correct answer: State licensure is a legal requirement set by each state; ABO certification is a voluntary national credential

State licensure is a legal requirement determined by individual states, while ABO certification is a nationally recognized voluntary professional credential.

Question 48: Combination antihistamine/mast cell stabilizer drops such as olopatadine (Pataday) are indicated for:

Allergic conjunctivitis (Correct answer)
Viral keratitis
Bacterial conjunctivitis
Glaucoma management

Correct answer: Allergic conjunctivitis

Olopatadine provides dual-action relief for allergic conjunctivitis by blocking histamine receptors and preventing mast cell degranulation.

Question 49: A patient with rheumatoid arthritis presents with a painless, white, avascular area of thinning at the limbus. What is the most likely diagnosis?

Episcleritis
Pterygium
Band keratopathy
Peripheral ulcerative keratitis (Correct answer)

Correct answer: Peripheral ulcerative keratitis

Peripheral ulcerative keratitis (PUK) is a limbal thinning condition associated with systemic autoimmune diseases like rheumatoid arthritis.

Question 50: In a state that does not require optician licensure, ABO certification primarily serves to:

Demonstrate voluntary professional competency to employers and patients (Correct answer)
Replace any requirement for supervised practice hours
Allow the optician to supervise licensed optometrists
Grant legal authority to perform refractions

Correct answer: Demonstrate voluntary professional competency to employers and patients

In unlicensed states, ABO certification voluntarily demonstrates a professional standard of competency and commitment to the field.

Question 51: For a frame with A=52, DBL=18, the standard PD (frame PD) equals:

70 mm (Correct answer)
52 mm
88 mm
34 mm

Correct answer: 70 mm

Frame PD = A + DBL = 52 + 18 = 70 mm; this represents the distance from one lens center to the other.

Question 52: A patient with long-standing hypertension presents with bilateral disc edema, flame-shaped hemorrhages, and cotton-wool spots. Which grade of Keith-Wagener-Barker hypertensive retinopathy does this represent?

Grade II
Grade IV
Grade III (Correct answer)
Grade I

Correct answer: Grade III

Grade III hypertensive retinopathy includes flame hemorrhages, cotton-wool spots, and hard exudates along with AV nicking.

Question 53: The Müller cells of the retina perform all of the following functions EXCEPT:

Providing structural support to the retinal architecture
Potassium buffering in the retina
Glutamate recycling at synapses
Phagocytosis of shed photoreceptor outer segments (Correct answer)

Correct answer: Phagocytosis of shed photoreceptor outer segments

Phagocytosis of shed photoreceptor outer segment discs is performed by the RPE, not Müller cells; Müller cells buffer K+, recycle glutamate, and provide structural support.

Question 54: A steep scleral lens fit (excessive vault) over a keratoconic cornea will MOST likely result in:

Corneal desiccation at 3 and 9 o'clock
Spectacle blur after removal
Excessive lens movement and decentration
Fogging of vision from a thickened, stagnant fluid reservoir (Correct answer)

Correct answer: Fogging of vision from a thickened, stagnant fluid reservoir

Excessive vault creates a thick, stagnant fluid reservoir that scatters light and reduces visual acuity, often described as 'fogging.'

Question 55: Microtropia (monofixation syndrome) is best characterized by:

A small-angle tropia with peripheral binocular fusion and central suppression scotoma (Correct answer)
A large-angle tropia with constant diplopia
Full bifoveal fusion with normal stereopsis
Complete absence of fixation in the deviating eye

Correct answer: A small-angle tropia with peripheral binocular fusion and central suppression scotoma

Monofixation syndrome (microtropia) features a small angle strabismus with a central suppression scotoma in the deviating eye but preserved peripheral fusion, giving reduced but measurable stereopsis.

Question 56: Which condition is characterized by the gradual clouding of the crystalline lens?

Retinal detachment
Glaucoma
Cataract (Correct answer)
Macular degeneration

Correct answer: Cataract

A cataract is the progressive opacification of the crystalline lens, typically age-related, causing decreased visual acuity, glare, and altered color perception.

Question 57: The Maddox rod test is primarily used to assess:

Binocular visual acuity under normal conditions
Stereoacuity in arc seconds
The magnitude and direction of a phoria (Correct answer)
Corneal topography

Correct answer: The magnitude and direction of a phoria

The Maddox rod converts a point light source into a streak, completely dissociating the eyes so that any phoria can be measured with neutralizing prisms.

Question 58: Which lens material property is most important in reducing lipid deposit formation on contact lenses?

Low water content and high silicone content
High water content
Ionic surface charge (FDA Group IV materials) (Correct answer)
High refractive index

Correct answer: Ionic surface charge (FDA Group IV materials)

FDA Group IV lenses (high water, ionic) attract the most protein and lipid deposits due to their ionic surface charge.

Question 59: A bifocal contact lens using an alternating (translating) design relies on which mechanism for near vision?

Simultaneous vision through concentric zones
Pupil-size-dependent optics
Diffractive optical zones
Lens translation downward on downgaze to position the near segment in front of the pupil (Correct answer)

Correct answer: Lens translation downward on downgaze to position the near segment in front of the pupil

Translating bifocal lenses shift downward in downgaze so the near segment aligns with the visual axis, similar to an executive bifocal spectacle lens.

Question 60: Topical carbonic anhydrase inhibitors (e.g., dorzolamide) lower IOP by:

Reducing aqueous humor production (Correct answer)
Constricting the trabecular meshwork
Elevating episcleral venous pressure
Increasing uveoscleral outflow

Correct answer: Reducing aqueous humor production

CAIs inhibit carbonic anhydrase in the ciliary body epithelium, reducing aqueous humor secretion and lowering IOP.

Question 61: A patient with myasthenia gravis presents with ptosis and diplopia that worsen with sustained upgaze and improve with rest. Which test is used to confirm the diagnosis at the bedside?

Cover-uncover test
Ice pack test (Correct answer)
Forced duction test
Maddox rod test

Correct answer: Ice pack test

Applying ice to a ptotic lid for 2 minutes reduces the ptosis in myasthenia gravis by slowing acetylcholinesterase activity at the neuromuscular junction.

Question 62: Which term describes a latent ocular deviation that is controlled by fusion and only becomes manifest when fusion is disrupted?

Tropia
Phoria (Correct answer)
Amblyopia
Diplopia

Correct answer: Phoria

A phoria (heterophoria) is a latent deviation kept latent by fusional vergence, only revealed by dissociation techniques such as the cover test.

Question 63: A +3.00 D thin lens in air has a focal length of:

33.3 cm (Correct answer)
0.33 cm
30 cm
3 cm

Correct answer: 33.3 cm

Focal length f = 1/F = 1/3.00 = 0.333 m = 33.3 cm.

Question 64: First-line topical antibiotic treatment for uncomplicated bacterial conjunctivitis typically includes:

Topical fluoroquinolone or polymyxin B/trimethoprim (Correct answer)
Oral tetracycline
Topical vancomycin
Systemic penicillin

Correct answer: Topical fluoroquinolone or polymyxin B/trimethoprim

Broad-spectrum topical antibiotics such as fluoroquinolones or polymyxin B combinations are first-line for uncomplicated bacterial conjunctivitis.

Question 65: The circle of least confusion in a Sturm's conoid is located:

At the anterior focal line
At the posterior focal line
Midway between the two focal lines (Correct answer)
At the retina in all cases

Correct answer: Midway between the two focal lines

The circle of least confusion is the round cross-section of Sturm's conoid located equidistant between the two focal lines.

Question 66: In the reduced eye model, what is the approximate refractive index used for the ocular media?

1.400
1.336 (Correct answer)
1.000
1.523

Correct answer: 1.336

The reduced eye model uses a single refractive index of approximately 1.336 to represent the combined ocular media.

Question 67: A rigid contact lens has a Dk of 100 and a center thickness of 0.20 mm. What is its Dk/t value?

500 (Correct answer)
100
20
50

Correct answer: 500

Dk/t = Dk ÷ thickness in cm = 100 ÷ 0.020 cm = 500 × 10⁻⁹ (Fatt units); dividing 100 by 0.02 gives 500.

Question 68: Which optical trait is the main distinguishing factor between an emmetropic and a myopic eye?

The myopic eye has a shorter axial length than the emmetropic eye
The myopic eye focuses light rays in front of the retina (Correct answer)
The myopic eye focuses light rays directly on the retina without accommodation
The myopic eye has a corneal curvature that is flatter than that of the emmetropic eye

Correct answer: The myopic eye focuses light rays in front of the retina

Blurred distance vision is a result of a myopic (nearsighted) eye's capacity to focus light rays in front of the retina rather than directly on it. A cornea that is excessively curved relative to the length of the eye or a longer axial length of the eye may be the cause of this disorder.

Question 69: A patient has a prescription of -3.00 -1.50 x 090. What is the power in the 180-degree meridian?

-4.50 D (Correct answer)
-1.00 D
-3.00 D
-1.50 D

Correct answer: -4.50 D

In the 180-degree meridian (perpendicular to axis 090), the full sphere plus cylinder power applies: -3.00 + (-1.50) = -4.50 D.

Question 70: What career advancement paths exist for ABO certified professionals?

Only changing careers provides advancement
Advancement requires leaving the field entirely
Leadership roles, specialized consulting, education and training, and executive management positions (Correct answer)
No advancement is possible beyond initial certification

Correct answer: Leadership roles, specialized consulting, education and training, and executive management positions

Certified professionals can advance through specialization, leadership roles, consulting, academic/training positions, and executive management within their field.

Question 71: What is the primary purpose of fenestrations (holes) in some rigid contact lens designs?

Improve tear circulation and reduce bubble entrapment (Correct answer)
Reduce lens weight
Improve oxygen transmission through the lens
Decrease lens flexure

Correct answer: Improve tear circulation and reduce bubble entrapment

Fenestrations allow improved tear exchange and prevent air bubbles from being trapped beneath the lens, though they are less commonly used with modern high-Dk materials.

Question 72: A patient with keratoconus is best managed with which contact lens modality?

Rigid gas-permeable (RGP) lens (Correct answer)
Extended-wear soft lens
Soft toric lens
Daily disposable spherical lens

Correct answer: Rigid gas-permeable (RGP) lens

RGP lenses vault the irregular cornea and provide a smooth refracting surface, making them the preferred option for keratoconus.

Question 73: Aspheric lens surfaces are used primarily to:

Add UV protection
Increase lens thickness for strength
Reduce peripheral aberrations and allow a flatter lens profile (Correct answer)
Increase chromatic aberration

Correct answer: Reduce peripheral aberrations and allow a flatter lens profile

Aspheric surfaces vary in curvature across the lens to minimize spherical and peripheral aberrations while enabling a thinner, flatter design.

Question 74: Which of the following is the most common cause of central retinal artery occlusion (CRAO)?

Embolism from carotid atherosclerosis (Correct answer)
Vasculitis
Vasospasm
Hypercoagulable state

Correct answer: Embolism from carotid atherosclerosis

Emboli from carotid artery atherosclerotic plaques are the most frequent cause of CRAO.

Question 75: Which instrument is used to objectively measure a patient's refractive error?

Tonometer
Autorefractor (Correct answer)
Pachymeter
Keratometer

Correct answer: Autorefractor

An autorefractor automatically determines the refractive error of the eye by measuring how light changes as it enters the eye.

Question 76: Which condition is an absolute contraindication to contact lens wear?

Aniridia with photophobia
Low refractive error
Mild seasonal allergic conjunctivitis
Active bacterial corneal ulcer (Correct answer)

Correct answer: Active bacterial corneal ulcer

An active corneal infection is an absolute contraindication because lens wear would exacerbate the infection and introduce additional pathogens.

Question 77: A patient with HLA-B27 positivity, low back pain, and recurrent unilateral anterior uveitis with hypopyon most likely has which systemic condition?

Ankylosing spondylitis (Correct answer)
Sarcoidosis
Juvenile idiopathic arthritis
Behçet disease

Correct answer: Ankylosing spondylitis

Ankylosing spondylitis is strongly associated with HLA-B27 and causes acute recurrent unilateral anterior uveitis.

Question 78: Which base curve selection guideline is most appropriate when fitting a standard soft lens?

Choose a base curve 0.5–1.0 mm flatter than flat K (Correct answer)
Select a base curve 1.0 mm flatter than flat K
Match base curve exactly to flat K reading
Use the steepest K reading as the base curve

Correct answer: Choose a base curve 0.5–1.0 mm flatter than flat K

Soft lenses are typically fit 0.5–1.0 mm flatter than the flat K to allow appropriate drape and movement.

Question 79: What is the importance of peer review in optometry?

Only management should review professional work
Peer review ensures quality, catches errors, provides learning opportunities, and maintains professional standards (Correct answer)
Peer review undermines professional confidence
Peer review is unnecessary for experienced professionals

Correct answer: Peer review ensures quality, catches errors, provides learning opportunities, and maintains professional standards

Peer review is a cornerstone of professional quality assurance, providing independent verification, knowledge sharing, and continuous improvement opportunities.

Question 80: A patient's keratometry readings are 44.00/47.00 @ 090. What type of corneal astigmatism is present?

With-the-rule astigmatism (Correct answer)
Against-the-rule astigmatism
Regular astigmatism, unclassified
Oblique astigmatism

Correct answer: With-the-rule astigmatism

With-the-rule astigmatism means the vertical meridian (90°) is steeper; here 47.00 D at 090 confirms the steeper vertical meridian.

Question 81: A new soft lens wearer reports blurry vision that clears momentarily after blinking. The MOST likely cause is:

Lens dehydration or poor wettability (Correct answer)
Incorrect lens power
Corneal edema
Giant papillary conjunctivitis

Correct answer: Lens dehydration or poor wettability

Post-blink clearing of blur suggests the tear film temporarily restores optical quality, pointing to lens dehydration or poor wettability.

Question 82: Prescribing topical corticosteroids for a patient with undiagnosed herpetic keratitis risks:

Reducing inflammation without risk
Worsening viral replication and potential corneal perforation (Correct answer)
Increased reflex tearing only
Pharmacological pupil dilation

Correct answer: Worsening viral replication and potential corneal perforation

Topical steroids suppress the immune response in HSV keratitis, allowing viral replication to accelerate and potentially causing corneal ulceration or perforation.

Question 83: What is the main way that astigmatism affects the retinal image quality?

By increasing the contrast of the retinal image
By creating multiple focal points within the eye (Correct answer)
By causing a uniform blurring across the entire image
By reducing the overall brightness of the image

Correct answer: By creating multiple focal points within the eye

Astigmatism is a refractive error caused by an irregular curvature of the cornea or lens, leading to light being focused at multiple points within the eye, either in front of or behind the retina, or both. This results in a distortion of the retinal image, affecting both horizontal and vertical lines, and can cause blurred or distorted vision at all distances.

Question 84: The Bielschowsky head tilt test is a critical diagnostic maneuver for identifying palsy of which cranial nerve?

Cranial nerve VI (abducens)
Cranial nerve III (oculomotor)
Cranial nerve IV (trochlear) (Correct answer)
Cranial nerve II (optic)

Correct answer: Cranial nerve IV (trochlear)

In trochlear (CN IV) palsy, tilting the head to the affected side increases the hyperdeviation because the superior rectus (an intorter) acts as an elevator when the superior oblique is paretic.

Question 85: A 35-year-old Black American presents with bilateral hilar adenopathy, anterior uveitis with mutton-fat KP, and elevated serum ACE. The most likely diagnosis is:

Tuberculosis
Sarcoidosis (Correct answer)
Sympathetic ophthalmia
Vogt-Koyanagi-Harada disease

Correct answer: Sarcoidosis

Sarcoidosis classically presents with bilateral hilar adenopathy, elevated ACE, and granulomatous anterior uveitis with mutton-fat KP.

Question 86: What does a flat-fitting soft contact lens typically demonstrate on slit lamp evaluation?

Lens decentration inferiorly
Central bearing with peripheral touch
No movement with bubbles trapped underneath
Excessive movement and edge standoff (Correct answer)

Correct answer: Excessive movement and edge standoff

A flat-fitting soft lens has a base curve that is flatter than the cornea, causing excessive movement, poor centration, and visible edge standoff.

Question 87: Which of the following best describes the primary purpose of the ABO Master certification?

It allows the holder to prescribe corrective lenses
It is required to supervise other opticians in all states
It replaces the need for state licensure
It recognizes advanced knowledge and expertise beyond basic ABO certification (Correct answer)

Correct answer: It recognizes advanced knowledge and expertise beyond basic ABO certification

ABO Master certification is a voluntary advanced credential recognizing superior knowledge in opticianry beyond the standard certification.

Question 88: What is the function of the "add power" in bifocal lenses?

To correct for distance vision in myopic patients
To provide additional magnification for near tasks in presbyopic patients (Correct answer)
To compensate for astigmatism in the horizontal meridian
To decrease the weight of the lens for hyperopic patients

Correct answer: To provide additional magnification for near tasks in presbyopic patients

In bifocal lenses, the term "add power" describes the extra magnification that is added to the bottom portion of the lens to help with near vision tasks. This is required for presbyopic patients whose lens flexibility has changed with age, making it impossible for them to focus or adjust for close work.

Question 89: Which parameter most directly influences the tear exchange beneath a rigid gas-permeable contact lens?

Edge lift (axial edge clearance) (Correct answer)
Center thickness
Lens diameter
Optical zone diameter

Correct answer: Edge lift (axial edge clearance)

Edge lift determines the amount of clearance at the lens periphery, directly controlling how freely tears can pump beneath the lens with each blink.

Question 90: Which type of cataract is most characteristically associated with long-term systemic corticosteroid use?

Posterior subcapsular cataract (Correct answer)
Cortical spoke cataract
Nuclear sclerotic cataract
Anterior subcapsular cataract

Correct answer: Posterior subcapsular cataract

Posterior subcapsular cataracts (PSC) are the classic steroid-induced and radiation-induced cataract type.

Question 91: What is the gold standard test for measuring intraocular pressure?

Schiotz tonometry
Non-contact tonometry (air puff)
Tono-Pen tonometry
Goldmann applanation tonometry (Correct answer)

Correct answer: Goldmann applanation tonometry

Goldmann applanation tonometry is considered the gold standard for IOP measurement, using the principle of applanating a fixed area of cornea (3.06mm diameter).

Question 92: Which of the following BEST describes 'limbal-to-limbal' fitting for a soft contact lens?

Lens diameter extends 1–2 mm beyond the HVID onto the sclera (Correct answer)
Lens covers only the pupillary zone
Lens diameter is 0.5 mm smaller than HVID
Lens diameter equals the horizontal visible iris diameter (HVID)

Correct answer: Lens diameter extends 1–2 mm beyond the HVID onto the sclera

Standard soft lenses are fit so their diameter extends approximately 1–2 mm beyond the limbus onto the sclera.

Question 93: Extended wear (EW) contact lenses primarily require higher Dk/t values because:

Closed-eye oxygen tension is much lower, requiring higher transmissibility to prevent hypoxia (Correct answer)
EW lenses must correct higher refractive errors
Higher Dk lenses are more resistant to deposits
The patient cannot insert or remove lenses daily

Correct answer: Closed-eye oxygen tension is much lower, requiring higher transmissibility to prevent hypoxia

During sleep, the palpebral conjunctiva reduces corneal oxygen supply to ~8%, so lenses with very high Dk/t (≥87 for EW) are needed to prevent hypoxia.

Question 94: A spectacle lens with a base curve of +6.00 D and back surface power of -2.00 D has a front vertex power of approximately:

+4.00 D (Correct answer)
+8.00 D
+6.00 D
+2.00 D

Correct answer: +4.00 D

In a thin lens approximation, total power = front surface + back surface = +6.00 + (-2.00) = +4.00 D.

Question 95: In a toric lens, the two principal meridians are oriented:

Perpendicular to each other (Correct answer)
Parallel to each other
At a 45° oblique angle
Identical in power

Correct answer: Perpendicular to each other

A toric lens has two principal meridians at 90° to each other, each with a different curvature and power, correcting astigmatism.

Question 96: Orthokeratology (ortho-K) lenses are fitted to achieve what primary effect?

Eliminate the need for toric lens designs
Correct presbyopia by changing lens power
Temporarily flatten the cornea to reduce myopia (Correct answer)
Increase corneal curvature for hyperopia correction

Correct answer: Temporarily flatten the cornea to reduce myopia

Orthokeratology uses reverse-geometry RGP lenses worn overnight to temporarily reshape (flatten) the central cornea, reducing myopia for daytime clear vision without spectacles.

Question 97: The Holladay-Prager formula and similar tools are used in contact lens practice primarily for:

Predicting lens rotation in toric fits
Measuring tear film breakup time
Determining scleral lens landing zone width
Calculating vertex distance power conversion (Correct answer)

Correct answer: Calculating vertex distance power conversion

Vertex distance power conversion formulas (like Holladay's) convert spectacle Rx to contact lens power, especially important above ±4.00 D.

Question 98: What is the function of the ciliary body?

To drain aqueous humor from the eye
To produce aqueous humor and control lens accommodation (Correct answer)
To protect the optic nerve
To produce vitreous humor

Correct answer: To produce aqueous humor and control lens accommodation

The ciliary body has two main functions: it produces aqueous humor and contains the ciliary muscle that controls accommodation by changing the shape of the lens.

Question 99: What career advancement paths exist for ABO certified professionals?

Only changing careers provides advancement
Leadership roles, specialized consulting, education and training, and executive management positions (Correct answer)
Advancement requires leaving the field entirely
No advancement is possible beyond initial certification

Correct answer: Leadership roles, specialized consulting, education and training, and executive management positions

Certified professionals can advance through specialization, leadership roles, consulting, academic/training positions, and executive management within their field.

Question 100: "Apical clearance" in the context of rigid gas permeable (RGP) lens fit refers to:

The alignment of the lens edge with the limbus
The lens completely covering the corneal apex without touching it
The lens resting directly on the corneal apex
The lens vaulting over the corneal apex with a thin layer of tears beneath (Correct answer)

Correct answer: The lens vaulting over the corneal apex with a thin layer of tears beneath

When discussing RPG lenses, apical clearance refers to the lens's vaulting over the corneal apex while preserving a little space between the lens and the cornea that is moistened with a thin coating of tears. This fitting technique is crucial for facilitating tear exchange, improving comfort, and guaranteeing that the cornea receives enough oxygen.

Question 101: A patient requires +2.50 D at the spectacle plane (12 mm vertex distance). What contact lens power is needed?

+2.44 D (Correct answer)
+2.37 D
+2.57 D
+2.50 D

Correct answer: +2.44 D

F_contact = F_spec / (1 + d × F_spec) = 2.50 / (1 + 0.012 × 2.50) = 2.50 / 1.03 ≈ +2.43 D, rounded to +2.44 D.

Question 102: Which lens material has the highest index of refraction among common ophthalmic materials?

Polycarbonate (1.586)
High-index 1.74 plastic (Correct answer)
Crown glass (1.523)
CR-39 (1.498)

Correct answer: High-index 1.74 plastic

High-index 1.74 plastic has the highest index of refraction commonly available, allowing the thinnest possible lens for high prescriptions.

Question 103: What is the recommended maximum time a conventional soft contact lens patient case should go before replacement?

1 year
3 months (Correct answer)
1 month
6 months

Correct answer: 3 months

Contact lens cases should be replaced every 3 months (or sooner if damaged) to reduce biofilm accumulation and contamination risk.

Question 104: The far point of a 5.00 D myope is located:

20 cm behind the eye
At infinity
20 cm in front of the eye (Correct answer)
50 cm in front of the eye

Correct answer: 20 cm in front of the eye

Far point distance = 1/F = 1/5.00 = 0.20 m = 20 cm in front of the eye for a myope.

Question 105: Which layer of the cornea is primarily responsible for maintaining corneal transparency through its pump function?

Endothelium (Correct answer)
Bowman's layer
Stroma
Epithelium

Correct answer: Endothelium

The corneal endothelium maintains transparency by actively pumping water out of the stroma, preventing corneal edema and clouding.

Question 106: Which condition is characterized by fine, diffuse corneal punctate staining in a patient wearing silicone hydrogel lenses with a preserved multipurpose solution?

Microbial keratitis
Solution-induced corneal staining (SICS) (Correct answer)
Acanthamoeba keratitis
Recurrent corneal erosion

Correct answer: Solution-induced corneal staining (SICS)

Solution-induced corneal staining (SICS) results from an incompatibility reaction between certain preservatives (especially PHMB or Alexidine) and silicone hydrogel lens materials.

Question 107: Which finding on fluorescein angiography is most characteristic of choroidal neovascularization (CNV)?

Early hyperfluorescence with late leakage (Correct answer)
Blocked fluorescence
Late staining without early filling
Window defect

Correct answer: Early hyperfluorescence with late leakage

CNV shows early hyperfluorescence as new vessels fill, followed by late leakage of dye beyond the lesion borders.

Question 108: Steroid-induced elevation of intraocular pressure occurs because corticosteroids:

Constrict the anterior chamber angle
Decrease uveoscleral outflow
Reduce outflow facility through the trabecular meshwork (Correct answer)
Increase aqueous humor production

Correct answer: Reduce outflow facility through the trabecular meshwork

Corticosteroids reduce aqueous outflow through the trabecular meshwork in susceptible individuals, elevating IOP without increasing production.

Question 109: The fovea centralis has the highest visual acuity because it contains predominantly which cell type?

Cone photoreceptors (Correct answer)
Rod photoreceptors
Müller cells
Retinal ganglion cells

Correct answer: Cone photoreceptors

The fovea centralis is packed with cone photoreceptors and lacks rods, enabling maximum visual acuity and color discrimination.

Question 110: A high-minus lens will have the thinnest point at the:

Nasal side
Optical center
Top of the lens
Edge of the lens (Correct answer)

Correct answer: Edge of the lens

Minus lenses are thicker at the center and thinner at the edges, so the edge is the thinnest point.

Question 111: A child presents with a unilateral white pupillary reflex (leukocoria). Which of the following is the most urgent diagnosis to rule out?

Coats disease
Retinoblastoma (Correct answer)
Persistent fetal vasculature
Congenital cataract

Correct answer: Retinoblastoma

Retinoblastoma is a life-threatening intraocular malignancy and must be excluded first in any child with leukocoria.

Question 112: A patient's over-refraction with a trial RGP lens yields −0.75 D sphere. What does this most likely indicate?

The lens power needs to be adjusted by −0.75 D (Correct answer)
Residual astigmatism is present
The lens diameter is too small
The lens is too steep

Correct answer: The lens power needs to be adjusted by −0.75 D

A spherical over-refraction result is simply added to or subtracted from the trial lens power to determine final lens power.

Question 113: When evaluating a fluorescein pattern for an RGP lens fit, a 'with-the-rule' corneal astigmat fitted with a spherical RGP will show:

Uniform alignment across the entire lens
Bearing centrally and pooling superiorly/inferiorly (Correct answer)
Bearing centrally and pooling nasally/temporally
Pooling centrally and bearing superiorly/inferiorly

Correct answer: Bearing centrally and pooling superiorly/inferiorly

In with-the-rule astigmatism, the vertical meridian is steeper; a spherical lens bears centrally along the flat horizontal meridian and shows pooling (fluorescein) along the steep vertical meridian.

Question 114: Add power in a bifocal lens is defined as:

The difference between OD and OS
Distance power minus intermediate power
Near power minus distance power (Correct answer)
The horizontal minus vertical power

Correct answer: Near power minus distance power

Add power equals the near prescription power minus the distance prescription power and is always a positive value.

Question 115: Lattice degeneration of the peripheral retina is most strongly associated with which refractive condition?

Myopia (Correct answer)
Hyperopia
Presbyopia
Astigmatism

Correct answer: Myopia

Lattice degeneration is found significantly more often in myopic eyes and increases the risk of retinal detachment.

Question 116: A dispensary employee accesses a patient's prescription records out of curiosity without a treatment, payment, or operations reason. This violates:

ANSI Z80.1 standards
OSHA recordkeeping requirements
FTC Eyeglass Rule
HIPAA minimum necessary standard (Correct answer)

Correct answer: HIPAA minimum necessary standard

HIPAA's minimum necessary standard requires that access to protected health information be limited to what is needed for a legitimate purpose.

Question 117: Optic nerve drusen (disc drusen) can mimic papilledema but can be differentiated by:

Presence of venous pulsations on disc
Autofluorescence on fundus autofluorescence imaging (Correct answer)
Lack of afferent pupillary defect
Normal visual acuity

Correct answer: Autofluorescence on fundus autofluorescence imaging

Disc drusen autofluoresce brightly on fundus autofluorescence (FAF) imaging, distinguishing them from true papilledema.

Question 118: Residual astigmatism with an RGP lens is BEST corrected by:

Increasing lens diameter
Decreasing center thickness
Steepening the base curve
Using a back-surface toric RGP lens (Correct answer)

Correct answer: Using a back-surface toric RGP lens

Residual (lenticular) astigmatism uncorrected by the tear lens requires a toric RGP design, typically back-surface toric.

Question 119: Which refractive condition results from a cornea with greater curvature in the vertical meridian than the horizontal?

Irregular astigmatism
Against-the-rule astigmatism
Oblique astigmatism
With-the-rule astigmatism (Correct answer)

Correct answer: With-the-rule astigmatism

With-the-rule astigmatism occurs when the vertical corneal meridian is steeper, requiring a minus cylinder axis at 180 degrees.

Question 120: The power of a spherical refracting surface is calculated using which formula?

P = (n + n') / r
P = n' / (n × r)
P = (n' - n) / r (Correct answer)
P = n × r

Correct answer: P = (n' - n) / r

The power of a single refracting surface is P = (n' - n) / r, where n' is the exit medium, n is the entry medium, and r is the radius in meters.

Question 121: A patient wearing monthly replacement soft lenses is non-compliant with lens care. Which complication are they at GREATEST risk for?

Corneal flattening
Myopia progression
Spectacle blur
Microbial keratitis, particularly Acanthamoeba (Correct answer)

Correct answer: Microbial keratitis, particularly Acanthamoeba

Poor lens hygiene and improper care (especially tap water use) dramatically increase risk of microbial and Acanthamoeba keratitis.

Question 122: In esotropia, the deviating eye turns in which direction?

Upward (superior)
Outward (temporal)
Inward (nasal) (Correct answer)
Downward (inferior)

Correct answer: Inward (nasal)

Esotropia is an inward (nasal/medial) deviation of the eye, commonly called 'crossed eyes.'

Question 123: A contact lens patient shows 3 and 9 o'clock corneal staining with an RGP lens. This is MOST likely caused by:

Solution toxicity
Lens power error
Excessive lens movement
Inadequate edge lift and poor tear meniscus at the lens periphery (Correct answer)

Correct answer: Inadequate edge lift and poor tear meniscus at the lens periphery

Desiccation at the 3 and 9 o'clock positions occurs when the nasal and temporal tear meniscus is disrupted by a poorly designed lens edge.

Question 124: In a patient with exotropia, the deviating eye turns in which direction?

Upward (superior)
Inward (nasal)
Downward (inferior)
Outward (temporal) (Correct answer)

Correct answer: Outward (temporal)

Exotropia is an outward (temporal/lateral) deviation of the eye, often called 'wall-eye.'

Question 125: A prescription reads -2.50 -1.00 x 180. What type of correction does this represent?

Simple hyperopic astigmatism
Compound myopic astigmatism (Correct answer)
Simple myopia
Mixed astigmatism

Correct answer: Compound myopic astigmatism

A negative sphere with a negative cylinder indicates compound myopic astigmatism, where both principal meridians are myopic.

Question 126: What is the impact of a lens's increased base curve on its optical power in ophthalmic optics?

It increases the lens's optical power (Correct answer)
It decreases the lens's optical power
It has no effect on the lens's power
It changes the lens's optical power depending on the lens material

Correct answer: It increases the lens's optical power

The curvature of a lens's front surface is referred to as its base curve. A lens's optical power increases as its base curve is increased since this produces a steeper curvature, which strengthens the lens's ability to bend light rays.

Question 127: A patient wearing soft contact lenses complains of reduced vision late in the day. Slit-lamp examination reveals corneal neovascularization at the superior limbus. What is the most likely cause?

Lens protein deposits
Giant papillary conjunctivitis
Chronic hypoxia from low-Dk lens (Correct answer)
Dry eye syndrome

Correct answer: Chronic hypoxia from low-Dk lens

Chronic hypoxia from wearing low-oxygen-transmissible (low-Dk) lenses causes limbal vessel ingrowth to compensate for oxygen deprivation.

Question 128: What visual field defect is most commonly associated with early open-angle glaucoma?

Bitemporal hemianopia
Homonymous hemianopia
Central scotoma
Arcuate scotoma (Correct answer)

Correct answer: Arcuate scotoma

An arcuate (Bjerrum) scotoma following the distribution of retinal nerve fiber bundles is the classic early visual field defect in open-angle glaucoma.

Question 129: What is the typical working distance used for near visual acuity testing?

100 cm (40 inches)
20 cm (8 inches)
40 cm (16 inches) (Correct answer)
60 cm (24 inches)

Correct answer: 40 cm (16 inches)

The standard near testing distance is 40 cm (16 inches), which corresponds to a 2.50 D accommodative demand.

Question 130: When fitting a patient with a prism half-eye spectacle for a hemianopia, the base direction of the Fresnel prism is placed toward the blind field. This displaces images in which direction?

Toward the apex of the prism, away from the blind field
No image displacement occurs; only magnification changes
Toward the base of the prism, into the seeing field
Toward the blind field, expanding its apparent boundary (Correct answer)

Correct answer: Toward the blind field, expanding its apparent boundary

A prism displaces images toward its apex; because the base is toward the blind field, the apex points into the seeing field, and images in the blind field are shifted toward the seeing side — effectively moving blind-field objects into the patient's seeing hemifield.

Question 131: Which of the following coatings primarily reduces internal lens reflections that reach the wearer's eyes from behind?

UV coating
Mirror coating
Anti-reflective (AR) coating (Correct answer)
Hard coat

Correct answer: Anti-reflective (AR) coating

AR coating reduces reflections on both front and back lens surfaces, including light entering from behind that would otherwise reflect into the wearer's eyes.

Question 132: Which lens treatment absorbs UV radiation below 400 nm and is built into the lens material rather than applied as a coating?

Mirror coating
AR coating
Hard coat
UV inhibitor (UV absorber) (Correct answer)

Correct answer: UV inhibitor (UV absorber)

A UV inhibitor is incorporated into the lens monomer during manufacturing, providing UV400 protection as an inherent lens property, not a surface treatment.

Question 133: Which corneal staining pattern is most characteristic of solution toxicity from contact lens care products?

Superior arcuate staining
Diffuse punctate epithelial staining across the entire cornea (Correct answer)
Central corneal staining only
3 and 9 o'clock peripheral staining

Correct answer: Diffuse punctate epithelial staining across the entire cornea

Solution toxicity typically presents as diffuse superficial punctate keratitis spread across the entire corneal surface.

Question 134: Which drug can be used to pharmacologically reverse iatrogenic pupil dilation?

Atropine
Pilocarpine (Correct answer)
Phenylephrine
Tropicamide

Correct answer: Pilocarpine

Pilocarpine, a cholinergic miotic, stimulates the iris sphincter muscle to constrict the pupil and reverse mydriasis.

Question 135: A contact lens prescription of -3.00 D corresponds to a spectacle prescription of -3.25 D at a 12mm vertex distance. Why is the contact lens power less minus?

The contact lens material absorbs some light
The tear film adds plus power
Manufacturing tolerances require rounding
The contact lens sits closer to the eye, requiring less minus power (Correct answer)

Correct answer: The contact lens sits closer to the eye, requiring less minus power

When a minus lens moves closer to the eye (decreasing vertex distance), less minus power is needed because the effective power of the lens increases at shorter distances.

Question 136: A patient with Stargardt disease has been referred for low vision rehabilitation. Which statement about this condition is most accurate for counseling purposes?

It is an age-related condition unlikely to progress further after age 60
It primarily affects peripheral vision and has no impact on reading
It is an autosomal recessive inherited dystrophy causing progressive central vision loss typically beginning in childhood or young adulthood (Correct answer)
It is caused by elevated intraocular pressure and can be treated with eye drops

Correct answer: It is an autosomal recessive inherited dystrophy causing progressive central vision loss typically beginning in childhood or young adulthood

Stargardt disease is the most common inherited macular dystrophy, autosomal recessive (ABCA4 mutation), causing central scotoma and progressive acuity loss usually before age 20.

Question 137: Beta-adrenergic blockers (e.g., timolol) lower intraocular pressure primarily by:

Increasing trabecular outflow
Decreasing aqueous humor production (Correct answer)
Relaxing the ciliary muscle
Constricting the pupil

Correct answer: Decreasing aqueous humor production

Beta-blockers reduce IOP by blocking β-adrenergic receptors on the ciliary epithelium, decreasing aqueous humor secretion.

Question 138: The segment height for a flat-top bifocal is measured from the:

Bottom of the frame to the top of the segment (Correct answer)
Top of the lens to the top of the segment
Pupil center to the bottom of the lens
Optical center to the segment line

Correct answer: Bottom of the frame to the top of the segment

Segment height is measured from the lowest point of the frame's inner groove (bottom) up to the top of the bifocal segment.

ABO Basic Optician Certification Exam

The ABO-NCLE Basic Optician Certification Exam tests knowledge and skills required for ophthalmic dispensing, covering optics, ocular anatomy, ophthalmic products, instrumentation, dispensing procedures, and contact lens fitting.

125

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120 min

Time Limit

70%

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