ABO Basic Optician Certification Exam — Questions and Answers

Question 1: What effect do variations in vertex distance have on a high-minus lens's effective power?

Increasing the vertex distance decreases the effective power (Correct answer)
Increasing the vertex distance increases the effective power
Changes in vertex distance have no impact on the effective power of high-minus lenses
Decreasing the vertex distance increases the effective power

Correct answer: Increasing the vertex distance decreases the effective power

The effective power of high-minus lenses decreases when the vertex distance—the separation between the lens's rear surface and cornea—increases. This is due to the fact that light rays must travel a greater distance to reach the retina, which lessens the lens's converging

Question 2: Subretinal fluid that shifts with positioning and no retinal break characterizes which type of retinal detachment?

Rhegmatogenous
Exudative (serous) (Correct answer)
Combined tractional-rhegmatogenous
Tractional

Correct answer: Exudative (serous)

Exudative retinal detachments have no break; subretinal fluid accumulates from underlying disease and gravitates with patient position.

Question 3: The minimum recommended Dk/t for daily wear soft lenses to avoid significant corneal hypoxia is approximately:

10 × 10⁻⁹
24 × 10⁻⁹ (Correct answer)
87 × 10⁻⁹
125 × 10⁻⁹

Correct answer: 24 × 10⁻⁹

Holden and Mertz established that a Dk/t of ≥24 × 10⁻⁹ is required for daily wear to limit chronic corneal edema to ≤4%.

Question 4: OSHA's requirement for occupational eye protection (29 CFR 1910.133) mandates that protective eyewear must meet standards set by:

ISO 8980-1
ASTM F803
ANSI Z87.1 (Correct answer)
ANSI Z80.1

Correct answer: ANSI Z87.1

OSHA references ANSI Z87.1 as the accepted standard for occupational eye and face protection devices.

Question 5: Which condition is characterized by fine, diffuse corneal punctate staining in a patient wearing silicone hydrogel lenses with a preserved multipurpose solution?

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

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 6: Which systemic medication is most commonly associated with cornea verticillata (whorl-like corneal epithelial deposits)?

Metformin
Lisinopril
Amiodarone (Correct answer)
Aspirin

Correct answer: Amiodarone

Amiodarone, an antiarrhythmic drug, commonly produces cornea verticillata due to drug accumulation in the corneal epithelium.

Question 7: A base-out prism placed before the right eye causes the image to appear displaced:

Superiorly
Nasally (toward the apex) (Correct answer)
Temporally (toward the base)
Inferiorly

Correct answer: Nasally (toward the apex)

Images are displaced toward the apex of a prism; base-out means the apex is nasal, so the image shifts nasally.

Question 8: A 70-year-old diabetic patient presents with new vessels at the disc (NVD) and vitreous hemorrhage. According to ETDRS criteria, this represents which stage of diabetic retinopathy?

High-risk proliferative DR (Correct answer)
Severe non-proliferative DR
Proliferative DR without high-risk characteristics
Moderate non-proliferative DR

Correct answer: High-risk proliferative DR

NVD of any size with vitreous hemorrhage meets ETDRS high-risk proliferative DR criteria, requiring prompt pan-retinal photocoagulation.

Question 9: The term 'effective diameter' (ED) of a lens refers to:

The horizontal width (A measurement) of the lens
The vertical height (B measurement) of the lens
The diameter of the smallest circle enclosing the entire lens shape (Correct answer)
The distance from lens center to the farthest edge

Correct answer: The diameter of the smallest circle enclosing the entire lens shape

ED is the diameter of the smallest circle that completely encloses the lens shape, used to determine minimum blank size needed.

Question 10: In the reduced eye model, what is the approximate refractive index used for the ocular media?

1.523
1.000
1.336 (Correct answer)
1.400

Correct answer: 1.336

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

Question 11: A patient's single vision lenses show prismatic displacement of images. Which instrument is used to measure this induced prism?

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

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 12: The scleral spur is a ridge of dense connective tissue that serves as the attachment point for which structure?

The corneal stroma anteriorly
The extraocular rectus muscles
The zonular fibers
The ciliary muscle and the posterior portion of the trabecular meshwork (Correct answer)

Correct answer: The ciliary muscle and the posterior portion of the trabecular meshwork

The scleral spur anchors the ciliary muscle and the posterior trabecular meshwork, and its position is a key gonioscopic landmark.

Question 13: What is the primary purpose of putting an anti-reflective (R) coating to ophthalmic lenses in terms of lens coatings?

To enhance the cosmetic Appearance of the lens
To reduce lens weight
To increase the transmission of light through the lens (Correct answer)
To protect the lens surface from scratches

Correct answer: To increase the transmission of light through the lens

Applying an anti-reflective (AR) coating to ophthalmic lenses is primarily done to decrease reflections, thereby increasing light transmission through the lens. This reduces glare and improves vision. It is especially useful in low light and for cutting down on nighttime glare from headlights and computer screens.

Question 14: The purpose of a verification log in an optical dispensary is primarily to:

Track inventory shrinkage and breakage
Record patient complaints for insurance purposes
Document that finished eyewear meets ANSI standards before dispensing (Correct answer)
Satisfy FTC Eyeglass Rule requirements

Correct answer: Document that finished eyewear meets ANSI standards before dispensing

A verification log documents that each pair of eyewear was checked against ANSI Z80.1 standards before being dispensed to the patient.

Question 15: In a toric lens, the two principal meridians are oriented:

Parallel to each other
At a 45° oblique angle
Perpendicular to each other (Correct answer)
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 16: What is the main way that astigmatism affects the retinal image quality?

By creating multiple focal points within the eye (Correct answer)
By increasing the contrast of the retinal image
By reducing the overall brightness of the image
By causing a uniform blurring across the entire 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 17: The choroid's primary physiological role is to:

Produce melanin for UV protection only
Supply oxygen and nutrients to the outer retina (Correct answer)
Regulate intraocular pressure
Provide structural support to the globe

Correct answer: Supply oxygen and nutrients to the outer retina

The choroid is a highly vascular layer that provides oxygen and nutrients to the outer retinal layers, including the photoreceptors.

Question 18: What is the importance of peer review in optometry?

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

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 19: What is the primary purpose of maintaining a returned goods log in an optical dispensary?

To record insurance denials and appeals
To track patient no-shows and appointment cancellations
To document lab remakes for trend analysis and quality improvement (Correct answer)
To comply with FTC warranty disclosure requirements

Correct answer: To document lab remakes for trend analysis and quality improvement

A returned goods log tracks remakes sent back to the lab, enabling the dispensary to identify patterns of lab error and drive quality improvement initiatives.

Question 20: 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 21: A higher Abbe value (V-number) in a lens material indicates:

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

Correct answer: Less chromatic aberration

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

Question 22: The American National Standards Institute (ANSI Z80.1) tolerance for cylinder axis on a prescription of -1.50 D cylinder is:

±7°
±10°
±5° (Correct answer)
±2°

Correct answer: ±5°

ANSI Z80.1 specifies a cylinder axis tolerance of ±5° for cylinder powers between 0.25 D and 2.00 D.

Question 23: How many continuing education credits must an ABO-certified optician earn during each 3-year renewal cycle?

18 credits (Correct answer)
12 credits
36 credits
24 credits

Correct answer: 18 credits

ABO requires 18 continuing education credits per 3-year renewal cycle to maintain certification.

Question 24: A new soft lens wearer reports blurry vision that clears momentarily after blinking. The MOST likely cause is:

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

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 25: A patient with 4.00 D of axial myopia has an eye axial length that is approximately how much longer than emmetropic?

2.0 mm
0.7 mm
3.0 mm
1.4 mm (Correct answer)

Correct answer: 1.4 mm

Each diopter of axial myopia corresponds to roughly 0.35 mm of excess axial length, so 4.00 D ≈ 1.4 mm.

Question 26: Which corneal staining pattern is most characteristic of solution toxicity from contact lens care products?

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

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 27: What measurement determines the vertical position of a progressive lens on the patient's face?

Frame wrap angle
Pantoscopic tilt
Pupillary distance
Fitting height (Correct answer)

Correct answer: Fitting height

The fitting height measures from the bottom of the lens to the center of the pupil, crucial for proper placement of the progressive corridor.

Question 28: Which of the following medications is most associated with corneal verticillata (vortex keratopathy)?

Amiodarone (Correct answer)
Rifampin
Hydroxychloroquine
Ethambutol

Correct answer: Amiodarone

Amiodarone deposits in the corneal epithelium in a whorl-like pattern (verticillata) in virtually all patients taking therapeutic doses.

Question 29: Drusen deposits in the macula are a hallmark sign of which condition?

Retinitis pigmentosa
Glaucoma
Diabetic retinopathy
Age-related macular degeneration (AMD) (Correct answer)

Correct answer: Age-related macular degeneration (AMD)

Drusen are yellowish deposits of lipid and protein that accumulate beneath the retinal pigment epithelium and are the earliest clinical sign of age-related macular degeneration.

Question 30: During slit-lamp evaluation of a newly fitted soft contact lens, what finding indicates the lens may be too tight?

Conjunctival blanching at the lens edge (Correct answer)
Excessive lens movement (>1.5 mm) on upward gaze
Lens edge standing off from the globe
Rapid tear film breakup over the lens surface

Correct answer: Conjunctival blanching at the lens edge

Conjunctival blanching (vessel compression) at the lens edge indicates excessive tightness causing mechanical restriction of blood flow at the limbus.

Question 31: Slab-off (bicentric grinding) is most commonly used to correct:

Progressive lens corridor swim
Chromatic aberration in high-index lenses
Vertical imbalance at the near zone in high anisometropic prescriptions (Correct answer)
Horizontal phorias in single vision 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 32: The approximate index of refraction of standard crown glass is:

1.52 (Correct answer)
1.60
1.40
1.74

Correct answer: 1.52

Standard crown glass has a refractive index of approximately 1.523, making it the traditional ophthalmic lens baseline.

Question 33: When fitting a soft toric lens, the lens consistently rotates 15° clockwise. What axis adjustment should be made?

Add 15° to the prescribed axis (Correct answer)
Order the lens with the same axis
Subtract 15° from the prescribed axis
Switch to a spherical lens

Correct answer: Add 15° to the prescribed axis

Using the LARS rule (Left Add, Right Subtract), clockwise rotation means you add degrees to the axis.

Question 34: Which of the following mistakes will a four-point touch test miss?

Excess face form
X-ing
Skewing (Correct answer)
All of the above can be detected using a four point touch

Correct answer: Skewing

A four-point touch test only checks the four corners, so it can miss skewing — a distortion of the overall shape that isn't revealed by testing corners alone. X-ing and excess face form produce errors detectable at the touch points, so skewing is the flaw this limited test fails to catch.

Question 35: The ganglion cells of the retina send their axons through which structure to reach the lateral geniculate nucleus?

Superior colliculus directly
Optic nerve, optic chiasm, and optic tract (Correct answer)
Optic chiasm only
Optic tract only

Correct answer: Optic nerve, optic chiasm, and optic tract

Retinal ganglion cell axons travel through the optic nerve, partially decussate at the optic chiasm, and continue as the optic tract to the LGN.

Question 36: A patient's spectacle magnification is greater than 1.0. This indicates the patient is:

Emmetropic
Presbyopic
Hyperopic (Correct answer)
Myopic

Correct answer: Hyperopic

Spectacle magnification >1.0 means the retinal image is larger than in the standard emmetropic eye, which occurs with plus (hyperopic) lenses.

Question 37: Topical NSAIDs (e.g., ketorolac, bromfenac) are used in ophthalmic practice primarily for:

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

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

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

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 39: Which of the following is the correct definition of 'legal blindness' in the United States for purposes of federal benefits eligibility?

Best-corrected visual acuity of 20/200 or worse in the better eye, OR visual field of 20 degrees or less in the better eye (Correct answer)
Best-corrected acuity of 20/100 or worse in both eyes
Total absence of light perception in both eyes
Visual acuity of 20/400 or worse in both eyes without correction

Correct answer: Best-corrected visual acuity of 20/200 or worse in the better eye, OR visual field of 20 degrees or less in the better eye

U.S. federal law defines legal blindness as BCVA ≤ 20/200 in the better-seeing eye or a visual field diameter ≤ 20° in the better eye.

Question 40: Aspheric lens surfaces are used primarily to:

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

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 41: A toric soft lens rotates 15° nasally on a patient's left eye. Using the LARS rule, how should the lens axis be adjusted?

Add 15° to the prescribed axis (Correct answer)
Rotate the lens 15° temporally by adjusting truncation
Subtract 15° from the prescribed axis
Reorder a lens with 15° less base curve

Correct answer: Add 15° to the prescribed axis

LARS (Left Add, Right Subtract) means if the lens rotates left (nasally on left eye), add that amount of degrees to the prescribed axis.

Question 42: What does the term 'emmetropia' describe?

An eye with hyperopia
An eye with myopia
An eye with astigmatism
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 43: Pigment epithelial detachment (PED) in age-related macular degeneration is best characterized on OCT as:

Intraretinal fluid between photoreceptors
Dome-shaped elevation of the RPE off Bruch's membrane (Correct answer)
Full-thickness defect through all retinal layers
Subretinal fluid under the neurosensory retina

Correct answer: Dome-shaped elevation of the RPE off Bruch's membrane

PED appears on OCT as a dome-shaped elevation of the RPE layer separated from Bruch's membrane by fluid or fibrovascular tissue.

Question 44: Which finding during a slit-lamp evaluation of a soft contact lens wearer suggests giant papillary conjunctivitis (GPC)?

Punctate epithelial erosions superiorly
Papillae greater than 0.3 mm on the upper tarsal conjunctiva (Correct answer)
Inferior corneal staining in a smile pattern
Limbal hyperemia only

Correct answer: Papillae greater than 0.3 mm on the upper tarsal conjunctiva

GPC is characterized by papillae ≥0.3 mm (often ≥1 mm in advanced cases) on the superior tarsal conjunctiva.

Question 45: 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 46: A positive result on the Randot Stereotest indicates:

Reduced contrast sensitivity
Monocular suppression of one eye
Bifoveal fixation and intact binocular vision (Correct answer)
A manifest strabismus

Correct answer: Bifoveal fixation and intact binocular vision

Passing the Randot Stereotest demonstrates bifoveal fixation and functional binocular vision with intact stereopsis.

Question 47: Fluorescein sodium dye is used in optometry primarily to:

Dilate the pupil for fundus exam
Evaluate corneal integrity and assess contact lens fitting (Correct answer)
Lower intraocular pressure
Measure visual acuity

Correct answer: Evaluate corneal integrity and assess contact lens fitting

Fluorescein stains damaged corneal epithelium and fluoresces under cobalt blue light, and is also used to evaluate rigid contact lens fluorescein patterns.

Question 48: What is the impact of a lens's increased base curve on its optical power in ophthalmic optics?

It changes the lens's optical power depending on the lens material
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

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

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

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 50: Polycarbonate lenses are the preferred material for safety eyewear primarily because of their:

Superior impact resistance (Correct answer)
High Abbe value reducing chromatic aberration
Lower cost compared to glass
High refractive index

Correct answer: Superior impact resistance

Polycarbonate's exceptional impact resistance makes it the material of choice for safety, sports, and children's eyewear.

Question 51: What is the recommended maximum time a conventional soft contact lens patient case should go before replacement?

1 month
1 year
3 months (Correct answer)
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 52: What does the term 'sagittal depth' describe in contact lens fitting?

The refractive index of the lens
The vertical distance from the chord diameter to the back surface of the lens (Correct answer)
The oxygen permeability of the lens material
The thickness of the lens at its center

Correct answer: The vertical distance from the chord diameter to the back surface of the lens

Sagittal depth (sag) is the depth of the 'bowl' of the lens, determined by both base curve and diameter, and it dictates how the lens vaults the eye.

Question 53: A contact lens patient shows 3 and 9 o'clock corneal staining with an RGP lens. This is MOST likely caused by:

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

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 54: What is the main advantage of giving the surface of RGP lenses a "plasma treatment"?

To improve the wettability and surface lubricity of the lens (Correct answer)
To enhance the hydrophobic properties of the lens surface
To increase the lens's resistance to scratches
To extend the usable life of the lens by preventing protein deposits

Correct answer: To improve the wettability and surface lubricity of the lens

RGP lenses are surface treated with plasma to increase the lens's wettability and surface lubricity. Through the reduction of surface tension and improvement of tear distribution over the lens, this treatment alters the lens surface to make it more compatible with the tear film, improving comfort.

Question 55: What is the primary measurement needed before fitting rigid gas permeable (RGP) contact lenses?

Palpebral fissure width
Pupil size
Corneal curvature (keratometry readings) (Correct answer)
Iris color

Correct answer: Corneal curvature (keratometry readings)

Keratometry readings provide the corneal curvature measurements essential for selecting the initial base curve of an RGP lens.

Question 56: The Maddox rod test is primarily used to assess:

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

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 57: 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:

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

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 58: A presbyopic patient with low myopia wants to try monovision contact lenses. Which eye is typically corrected for distance vision?

Either eye, patient preference only
The eye with less astigmatism
Non-dominant eye
Dominant eye (Correct answer)

Correct answer: Dominant eye

In monovision, the dominant eye is corrected for distance and the non-dominant eye for near.

Question 59: Clinically normal stereoacuity is typically defined as a threshold of:

100–200 arc seconds
40 arc seconds or better (Correct answer)
500 arc seconds
1,000 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 60: Which of the following BEST describes 'limbal-to-limbal' fitting for a soft contact lens?

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

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 61: How should ABO professionals approach client or stakeholder communication?

Use clear, professional language appropriate to the audience, confirm understanding, and document key communications (Correct answer)
Use technical jargon regardless of the audience
Communication skills are unimportant for technical professionals
Only communicate in writing, never verbally

Correct answer: Use clear, professional language appropriate to the audience, confirm understanding, and document key communications

Effective communication tailored to the audience's knowledge level is essential for building trust, ensuring understanding, and achieving professional objectives.

Question 62: A +2.00 D lens is placed 12 mm in front of the corneal plane. What is the equivalent power at the corneal plane?

+1.90 D
+2.05 D (Correct answer)
+2.10 D
+1.95 D

Correct answer: +2.05 D

Using F' = F / (1 - dF) = 2.00 / (1 - 0.012 × 2.00) = 2.00 / 0.976 ≈ +2.05 D.

Question 63: Which finding best differentiates wet (neovascular) AMD from dry AMD on clinical exam?

Pigmentary changes in the RPE
Geographic atrophy of the RPE
Subretinal fluid or hemorrhage at the macula (Correct answer)
Drusen in the macula

Correct answer: Subretinal fluid or hemorrhage at the macula

Subretinal fluid or hemorrhage from CNV defines wet AMD; drusen and geographic atrophy are features of dry AMD.

Question 64: The retinal blood supply from the central retinal artery nourishes which retinal layers?

The inner two-thirds of the retina (inner nuclear layer and inward) (Correct answer)
The entire retina including the RPE
Only the outer retina including photoreceptors
Only the ganglion cell layer

Correct answer: The inner two-thirds of the retina (inner nuclear layer and inward)

The central retinal artery supplies the inner two-thirds of the retina (from the nerve fiber layer to the inner nuclear layer), while the outer retina is supplied by the choroid.

Question 65: "Apical clearance" in the context of rigid gas permeable (RGP) lens fit refers to:

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

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 66: Lenticular lens design is most commonly used when:

Anti-reflective coating is applied
Prism correction is needed
Very high plus powers are needed (Correct answer)
High minus powers are needed

Correct answer: Very high plus powers are needed

Lenticular design places full correction only in a central optical zone, reducing weight and thickness for very high plus prescriptions.

Question 67: Which lens power would be prescribed for a patient with +3.00 D of hyperopia?

Concave (minus) lens of -3.00 D
Cylindrical lens of 3.00 D
Prism lens of 3.00 prism diopters
Convex (plus) lens of +3.00 D (Correct answer)

Correct answer: Convex (plus) lens of +3.00 D

Hyperopia requires a convex (plus) lens to add convergence and move the focal point forward onto the retina.

Question 68: Which magnification formula correctly calculates the required add power for a patient with 20/200 acuity who wants to read standard newsprint (20/40 equivalent)?

Add = 1/working distance in meters
Add = (20/200) / (20/40) × 4D = 20D (Correct answer)
Add = distance acuity denominator / goal acuity denominator × 2.5D
Add = 1 / (visual acuity in decimal)

Correct answer: Add = (20/200) / (20/40) × 4D = 20D

The required magnification is 200/40 = 5×, and since 1× requires approximately 4D, the needed add is 5 × 4D = 20D.

Question 69: The power of a spherical refracting surface is calculated using which formula?

P = (n' - n) / r (Correct answer)
P = (n + n') / r
P = n' / (n × r)
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 70: What is the minimum thickness requirement for safety lenses meeting ANSI Z87.1 standards?

0.5 mm for trivex
1.0 mm for all lenses
2.0 mm for glass lenses (Correct answer)
3.0 mm for polycarbonate

Correct answer: 2.0 mm for glass lenses

ANSI Z87.1 safety standards require dress safety glass lenses to have a minimum thickness of 2.0 mm. Polycarbonate and trivex have different requirements due to their impact resistance.

Question 71: What is the typical working distance used for near visual acuity testing?

100 cm (40 inches)
60 cm (24 inches)
40 cm (16 inches) (Correct answer)
20 cm (8 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 72: A base curve of +6.00 D is selected for a +4.00 D lens. This is best described as a:

Flat curve lens
Lenticular design
Corrected curve (best-form) lens (Correct answer)
Deep curve lens

Correct answer: Corrected curve (best-form) lens

A corrected curve (best-form) lens uses a specific base curve chosen to minimize aberrations for a given prescription power.

Question 73: Residual astigmatism with an RGP lens is BEST corrected by:

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

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 74: Which condition is characterized by a ring scotoma that most severely affects mobility and orientation rather than fine reading tasks in early stages?

Central serous chorioretinopathy
Age-related macular degeneration
Diabetic macular edema
Retinitis pigmentosa (Correct answer)

Correct answer: Retinitis pigmentosa

Retinitis pigmentosa causes progressive peripheral field loss (ring scotoma) that impairs mobility and night vision while central acuity for reading is preserved until late stages.

Question 75: A patient with 20/160 BCVA wants to read a medicine label with 1M print. Using the Kestenbaum rule, what approximate add power is indicated?

2D
16D
8D (Correct answer)
4D

Correct answer: 8D

The Kestenbaum rule estimates the required add as 1 / (distance acuity in decimal); 20/160 = 0.125 decimal, so 1/0.125 = 8D.

Question 76: What is the importance of peer review in optometry?

Peer review is unnecessary for experienced professionals
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

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 77: Is it possible to heat a frame till it yields to its own weight?

Optyl (Correct answer)
None of the above
Zyle
Nylon

Correct answer: Optyl

Optyl is the frame material with thermoplastic properties pronounced enough that it can become so pliable when heated that it deforms under its own weight. Zyl and nylon do not soften to that degree under heating, so Optyl is the correct answer.

Question 78: A 45-year-old presents with a sudden, painful red eye, corneal edema, mid-dilated non-reactive pupil, and IOP of 58 mmHg. What is the most likely diagnosis?

Hypopyon
Acute angle-closure glaucoma (Correct answer)
Acute anterior uveitis
Neovascular glaucoma

Correct answer: Acute angle-closure glaucoma

Acute angle-closure glaucoma presents with a painful red eye, corneal edema, mid-dilated pupil, and markedly elevated IOP.

Question 79: The fovea centralis has the highest visual acuity because it contains predominantly which cell type?

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

Correct answer: Cone photoreceptors

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

Question 80: A bitoric RGP lens is indicated when the difference between corneal toricity and residual astigmatism exceeds what threshold?

1.50 D
0.50 D
1.00 D (Correct answer)
0.75 D

Correct answer: 1.00 D

When residual astigmatism (internal astigmatism not corrected by the lens-tear interface) exceeds approximately 1.00 D, a bitoric lens design is indicated.

Question 81: Which type of bifocal segment provides the widest near reading area?

Executive (full-width) segment (Correct answer)
Flat-top 28 segment
Round segment (22mm)
Flat-top 35 segment

Correct answer: Executive (full-width) segment

The executive (Franklin) bifocal runs the full width of the lens, providing the widest possible near reading zone.

Question 82: A patient with HLA-B27 positivity, low back pain, and recurrent unilateral anterior uveitis with hypopyon most likely has which systemic condition?

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

Correct answer: Ankylosing spondylitis

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

Question 83: Progressive addition lenses (PALs) differ from bifocals primarily because they:

Are thicker at the center
Have a visible dividing line
Provide only distance correction
Offer a gradual power change from distance to near (Correct answer)

Correct answer: Offer a gradual power change from distance to near

PALs provide a continuous, gradual power progression eliminating the visible segment line of bifocals.

Question 84: What is the function of the "add power" in bifocal lenses?

To correct for distance vision in myopic patients
To compensate for astigmatism in the horizontal meridian
To provide additional magnification for near tasks in presbyopic patients (Correct answer)
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 85: In retinoscopy, a 'with' motion of the reflex indicates what type of refractive error?

Hyperopia or insufficient minus correction (Correct answer)
Emmetropia
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 86: Under ANSI Z80.1, the distance power tolerance for lenses with power greater than ±6.50D is:

±2% of the power (Correct answer)
±0.50D
±0.25D
±0.13D

Correct answer: ±2% of the power

For lenses with powers greater than ±6.50D, ANSI Z80.1 specifies a tolerance of ±2% of the specified power.

Question 87: The Holladay-Prager formula and similar tools are used in contact lens practice primarily for:

Measuring tear film breakup time
Predicting lens rotation in toric fits
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 88: A patient wearing monthly replacement soft lenses is non-compliant with lens care. Which complication are they at GREATEST risk for?

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

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 89: What qualifications are needed for advanced optometry practice?

Advanced practice requires no formal credentials
No additional qualifications beyond initial certification
Advanced certifications, specialized training, demonstrated experience, and ongoing professional development (Correct answer)
Only a college degree in any subject

Correct answer: Advanced certifications, specialized training, demonstrated experience, and ongoing professional development

Advanced practice requires building upon foundational knowledge through specialized certifications, targeted training, and demonstrated competence in specific areas.

Question 90: The following factors are most strongly linked to the development of microbial keratitis in contact lens wearers:

Wearing RGP lenses with a high Dk/t value
Daily wear of silicone hydrogel lenses
Use of daily disposable lenses
Extended (overnight) wear of any contact lens type (Correct answer)

Correct answer: Extended (overnight) wear of any contact lens type

the possibility of getting the serious corneal infection known as microbial keratitis. is most closely linked to prolonged (overnight) contact lens usage of any kind. Due to the possibility of bacterial contamination and decreased oxygen supply to the cornea when you sleep, this practice can greatly raise your risk of infection.

Question 91: What is the primary advantage of polycarbonate lenses over CR-39?

Superior impact resistance (Correct answer)
Better optical clarity
Easier to tint
Higher Abbe value

Correct answer: Superior impact resistance

Polycarbonate is significantly more impact-resistant than CR-39, making it the preferred material for safety eyewear and children's glasses.

Question 92: Lattice degeneration of the peripheral retina is most strongly associated with which refractive condition?

Myopia (Correct answer)
Astigmatism
Hyperopia
Presbyopia

Correct answer: Myopia

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

Question 93: The Bielschowsky head tilt test is a critical diagnostic maneuver for identifying palsy of which cranial nerve?

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

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 94: What career advancement paths exist for ABO certified professionals?

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
Only changing careers provides advancement

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 95: A patient with central scotoma due to macular degeneration is taught eccentric viewing. The preferred retinal locus (PRL) is most commonly located in which direction relative to the scotoma?

Inferior to the scotoma
Temporal to the scotoma in all patients
Superior to the scotoma
The PRL location varies by individual and must be determined clinically (Correct answer)

Correct answer: The PRL location varies by individual and must be determined clinically

The PRL develops spontaneously in a location that varies among individuals, and clinical assessment (e.g., microperimetry or scanning laser ophthalmoscopy) is needed to identify it.

Question 96: Which drug class is typically considered first-line pharmacotherapy for primary open-angle glaucoma (POAG) in the US?

Antifungals
Anticholinergics
Antihistamines
Prostaglandin analogs (Correct answer)

Correct answer: Prostaglandin analogs

Prostaglandin analogs such as latanoprost are first-line for POAG due to their strong IOP-lowering efficacy and once-daily dosing convenience.

Question 97: Which prism effect occurs when a myopic patient looks through the upper portion of a single-vision minus lens while reading?

No prism effect
Base-up prism (Correct answer)
Base-down prism
Base-in prism

Correct answer: Base-up prism

A minus lens creates base-up prismatic effect in its upper portion due to Prentice's rule, which can cause reading difficulties.

Question 98: Which structure of the eye is primarily responsible for focusing light at different distances?

Vitreous humor
Cornea
Crystalline lens (Correct answer)
Iris

Correct answer: Crystalline lens

The crystalline lens changes shape through accommodation to focus light from objects at varying distances onto the retina.

Question 99: When wearing soft contact lenses, "lens dehydration" is a problem that can cause discomfort. What is the typical cause of this problem?

Deceased blink rate
Excessive tear production
High water content in the lens materials
Low humidity environments (Correct answer)

Correct answer: Low humidity environments

Low humidity settings can make lens dryness worse for people who wear soft contact lenses. Under some circumstances, the water in the hydrogel substance of the lens may evaporate more quickly than usual, causing lens shrinkage and increased friction between the lens and the surface of the eye to produce discomfort.

Question 100: The primary purpose of a suppression scotoma in a patient with constant strabismus is to:

Improve contrast sensitivity in the fixing eye
Correct the underlying refractive error
Eliminate diplopia by inhibiting the image from the deviating eye's fovea (Correct answer)
Increase the amplitude of accommodation

Correct answer: Eliminate diplopia by inhibiting the image from the deviating eye's fovea

Cortical suppression of the fovea of the deviating eye is an adaptive response to prevent diplopia (and visual confusion) caused by the misaligned eye.

Question 101: A patient wearing silicone hydrogel lenses develops superior epithelial arcuate lesions (SEALs). The most appropriate initial management is:

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

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 102: A low vision patient is trained in 'scanning' using a handheld telescope. The direction of telescope movement to locate an object to the patient's right should be:

Move the telescope to the right, in the same direction as the target (Correct answer)
Move the telescope to the left (opposite direction) because the image is inverted
Rotate the telescope clockwise regardless of target position
Keep the telescope stationary and rotate the head

Correct answer: Move the telescope to the right, in the same direction as the target

An astronomical (inverting) telescope reverses image direction, but a Galilean (erect-image) telescope used for spotting moves in the same direction as the target; for clinical training, patients learn to move toward the target.

Question 103: Which parameter primarily determines the oxygen transmissibility (Dk/t) of a contact lens?

Lens diameter
Center thickness and material Dk (Correct answer)
Base curve radius
Water content alone

Correct answer: Center thickness and material Dk

Dk/t is calculated by dividing the material's oxygen permeability (Dk) by the lens center thickness (t).

Question 104: Why are rigid gas permeable (RGP) lenses designed with a "back surface toric" design for specific corneal shapes used in this way?

To enhance oxygen transmission through the lens
To increase the lens's resistance to deposit formation
To improve lens stabilization on the cornea
To match the lens to the toric shape of the cornea for better fit (Correct answer)

Correct answer: To match the lens to the toric shape of the cornea for better fit

RGP lenses feature a rear surface toric design to better fit and conform the lens to the toric, or irregularly shaped, cornea.

Question 105: 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 base curve of the lens
The water content of the lens
The stabilization mechanism of the lens (Correct answer)

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 106: What does a myopic patient experience without corrective lenses?

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

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 107: The angle kappa is defined as the angle between the:

Visual axis and the optical axis of the eye
Corneal reflex and the center of the pupil
Pupillary axis and the visual axis (Correct answer)
Line of sight and the optical axis

Correct answer: Pupillary axis and the visual axis

Angle kappa is the angle between the pupillary axis (perpendicular to the cornea through the center of the pupil) and the visual axis (fovea to fixation point).

Question 108: Haab's striae in the cornea of an infant indicate which diagnosis?

Birth trauma (forceps delivery)
Keratoconus
Congenital glaucoma (buphthalmos) (Correct answer)
Interstitial keratitis

Correct answer: Congenital glaucoma (buphthalmos)

Haab's striae are breaks in Descemet's membrane caused by elevated IOP stretching the infant eye in congenital glaucoma.

Question 109: Which parameter most directly influences the tear exchange beneath a rigid gas-permeable contact lens?

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

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

Axial myopia (Correct answer)
Refractive myopia
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 111: A patient's keratometry readings are 44.00/47.00 @ 090. What type of corneal astigmatism is present?

Oblique astigmatism
With-the-rule astigmatism (Correct answer)
Regular astigmatism, unclassified
Against-the-rule 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 112: A patient whose exophoria is significantly greater at distance than at near most likely has which binocular vision condition?

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

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

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

Correct answer: Keratoconus

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

Question 114: Which base curve selection guideline is most appropriate when fitting a standard soft lens?

Match base curve exactly to flat K reading
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
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 115: Optic nerve drusen (disc drusen) can mimic papilledema but can be differentiated by:

Lack of afferent pupillary defect
Presence of venous pulsations on disc
Autofluorescence on fundus autofluorescence imaging (Correct answer)
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 116: 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)
Higher Dk lenses are more resistant to deposits
The patient cannot insert or remove lenses daily
EW lenses must correct higher refractive errors

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 117: Oblique astigmatism refers to astigmatism with principal meridians oriented at:

Between 30–60 and 120–150 degrees (Correct answer)
0 and 90 degrees
45 and 135 degrees
Any axis other than 180 and 090

Correct answer: Between 30–60 and 120–150 degrees

Oblique astigmatism is conventionally defined as astigmatism with the principal meridians between 30–60 degrees and 120–150 degrees.

Question 118: Which lens material property is most important in reducing lipid deposit formation on contact lenses?

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

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

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

Correct answer: 33.3 cm

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

Question 120: When is it appropriate to use a slab-off prism?

To improve cosmetic appearance of thick lenses
To correct horizontal phoria
To correct vertical imbalance in anisometropic patients wearing multifocals (Correct answer)
To reduce lens thickness in high minus prescriptions

Correct answer: To correct vertical imbalance in anisometropic patients wearing multifocals

Slab-off (bicentric grinding) is used to neutralize the differential vertical prismatic effect that occurs when anisometropic patients look through the near segment of multifocal lenses.

Question 121: Which lens material has the highest Abbe value among common ophthalmic materials?

1.74 high-index
Polycarbonate
Trivex
CR-39 (plastic) (Correct answer)

Correct answer: CR-39 (plastic)

CR-39 has an Abbe value of approximately 58, the highest among common ophthalmic lens materials, meaning least chromatic aberration.

Question 122: 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 sits closer to the eye, requiring less minus power (Correct answer)
The tear film adds plus power
Manufacturing tolerances require rounding
The contact lens material absorbs some light

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 123: Which of the following is the correct definition of the 'far point' in hyperopia?

The midpoint of the accommodative range
The point at which accommodation is fully relaxed at distance
A real point located in front of the eye
A virtual point located behind the eye (Correct answer)

Correct answer: A virtual point located behind the eye

In hyperopia, the far point is a virtual conjugate point located behind the eye because the relaxed eye's focal point falls behind the retina.

Question 124: Which lens type is used to correct myopia?

Concave (minus) (Correct answer)
Plano
Convex (plus)
Prism

Correct answer: Concave (minus)

Concave minus lenses diverge light to shift the focal point back onto the retina in myopic eyes.

Question 125: Which drug can be used to pharmacologically reverse iatrogenic pupil dilation?

Phenylephrine
Atropine
Tropicamide
Pilocarpine (Correct answer)

Correct answer: Pilocarpine

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

Question 126: Which layer of the cornea is primarily responsible for maintaining corneal transparency through its pump function?

Stroma
Bowman's layer
Endothelium (Correct answer)
Epithelium

Correct answer: Endothelium

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

Question 127: What visual field defect is most commonly associated with early open-angle glaucoma?

Central scotoma
Homonymous hemianopia
Bitemporal hemianopia
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 128: When evaluating a fluorescein pattern for an RGP lens fit, a 'with-the-rule' corneal astigmat fitted with a spherical RGP will show:

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

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 129: Which cranial nerve innervates the lateral rectus muscle?

Oculomotor nerve (CN III)
Abducens nerve (CN VI) (Correct answer)
Optic nerve (CN II)
Trochlear nerve (CN IV)

Correct answer: Abducens nerve (CN VI)

The abducens nerve (cranial nerve VI) innervates the lateral rectus muscle, which is responsible for abducting (turning outward) the eye.

Question 130: The far point of a 5.00 D myope is located:

20 cm in front of the eye (Correct answer)
At infinity
50 cm in front of the eye
20 cm behind 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 131: Under ANSI Z80.3, sunlens luminous transmittance categories range from Category 0 to Category 4. What does Category 4 indicate?

Very dark lenses (3-8% transmittance) not suitable for driving (Correct answer)
Medium tints for general use, 18-43% transmittance
Clear lenses with no tint, 80-100% transmittance
Light tints suitable for indoor use, 43-80% transmittance

Correct answer: Very dark lenses (3-8% transmittance) not suitable for driving

Category 4 sunlenses have very dark tints with only 3-8% luminous transmittance and are not recommended for use while driving.

Question 132: What is the approximate refractive power of the human cornea?

10 diopters
60 diopters
43 diopters (Correct answer)
20 diopters

Correct answer: 43 diopters

The cornea contributes approximately 43 diopters (about two-thirds) of the eye's total refractive power of approximately 60 diopters.

Question 133: The limbus is clinically important because it contains:

Only melanocytes
Only trabecular meshwork
Only corneal stem cells
Corneal stem cells, aqueous drainage structures, and is a surgical landmark (Correct answer)

Correct answer: Corneal stem cells, aqueous drainage structures, and is a surgical landmark

The limbus contains corneal epithelial stem cells (at the palisades of Vogt), drainage structures, and is used as a landmark for surgical incisions.

Question 134: 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?

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

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

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

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

Autorefractor (Correct answer)
Tonometer
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 137: A high-minus lens will have the thinnest point at the:

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

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

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

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.

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

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