NBEO Part I Applied Basic Science (ABS) — Optometry Board Exam — Questions and Answers

Question 1: The mechanism of action of carbonic anhydrase inhibitors (e.g., dorzolamide) in glaucoma treatment is:

Stimulating beta-1 receptors to increase trabecular outflow
Blocking alpha-2 receptors to reduce episcleral venous pressure
Increasing uveoscleral outflow by relaxing ciliary muscle
Inhibiting carbonic anhydrase II in the ciliary epithelium to reduce aqueous production (Correct answer)

Correct answer: Inhibiting carbonic anhydrase II in the ciliary epithelium to reduce aqueous production

CAIs inhibit carbonic anhydrase type II in the non-pigmented ciliary epithelium, reducing bicarbonate and sodium transport that drives aqueous secretion.

Question 2: What does the 'plano' carrier design in a bitoric RGP lens achieve?

Reduces lens thickness to improve oxygen transmissibility
Increases optical clarity for presbyopic patients
Minimizes lens rocking by correcting for corneal toricity mechanically (Correct answer)
Centers the lens over the pupil in patients with large angle kappa

Correct answer: Minimizes lens rocking by correcting for corneal toricity mechanically

A plano carrier (back surface toric, front surface sphere) corrects corneal toricity mechanically to stabilize the lens and reduce rocking without introducing cylinder in the optic zone.

Question 3: The leading cause of preventable blindness globally, which optometrists actively screen for, is:

Onchocerciasis
Cataract (Correct answer)
Glaucoma
Trachoma

Correct answer: Cataract

Cataract is responsible for approximately 50% of global blindness and 33% of visual impairment worldwide; it is preventable and treatable with surgery.

Question 4: Which contact lens material parameter describes the amount of oxygen that actually reaches the cornea?

Water content
Modulus of elasticity
Base curve radius
Dk/t (oxygen transmissibility) (Correct answer)

Correct answer: Dk/t (oxygen transmissibility)

Dk/t (oxygen transmissibility) is the measure of oxygen flux through a specific lens thickness and determines how much oxygen reaches the corneal epithelium.

Question 5: Chromatic aberration in the eye is primarily responsible for which clinical phenomenon?

Blue light focusing slightly anterior to red light (longitudinal chromatic aberration) (Correct answer)
Reduced contrast sensitivity at spatial frequencies above 10 cpd
Prism effect at the lens periphery causing rainbows
Increased glare sensitivity in mesopic conditions

Correct answer: Blue light focusing slightly anterior to red light (longitudinal chromatic aberration)

The ocular media have higher refractive index for shorter wavelengths; blue light focuses about 2D anterior to red, a phenomenon used in the duochrome (red-green) test.

Question 6: What type of insurance coverage is crucial for protecting an optometric practice against data breaches and cyber-attacks?

Professional liability insurance
Vision insurance
Property insurance
Cyber liability insurance (Correct answer)

Correct answer: Cyber liability insurance

Cyber liability insurance provides protection against losses resulting from data breaches, cyber-attacks, and other cybersecurity issues.

Question 7: Drusen deposits beneath the retinal pigment epithelium are most associated with which disease process?

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

Correct answer: Age-related macular degeneration

Drusen are extracellular deposits between the RPE and Bruch's membrane and are the hallmark early finding of age-related macular degeneration.

Question 8: Legal blindness in the United States is defined as best-corrected visual acuity of:

20/200 in one eye regardless of the fellow eye
20/400 or worse in both eyes
20/200 or worse in the better eye, or visual field ≤20° (Correct answer)
Less than 20/100 in the worse eye

Correct answer: 20/200 or worse in the better eye, or visual field ≤20°

US legal blindness is BCVA ≤20/200 in the better-seeing eye OR a remaining visual field of ≤20° diameter (central island or tunnel vision).

Question 9: Prism adaptation test before strabismus surgery is used to:

Test for sensory suppression in the deviating eye
Assess motor fusion amplitude before therapy
Measure the AC/A ratio for bifocal prescription
Reveal the full angle of deviation and predict surgical success (Correct answer)

Correct answer: Reveal the full angle of deviation and predict surgical success

The prism adaptation test neutralizes the deviation with Fresnel prisms to unmask the full surgical angle and improve the precision of the planned surgery.

Question 10: The most common cause of irreversible vision loss in Americans over age 65 is:

Glaucoma
Diabetic retinopathy
Age-related macular degeneration (Correct answer)
Cataracts

Correct answer: Age-related macular degeneration

AMD is the leading cause of irreversible (non-correctable) vision loss in adults over 65 in the United States, primarily affecting central vision.

Question 11: Which layer of the cornea is replaced by pump activity and is responsible for maintaining corneal deturgesence?

Epithelium
Stroma
Endothelium (Correct answer)
Bowman's layer

Correct answer: Endothelium

The corneal endothelium maintains corneal clarity through active fluid pumping to prevent swelling of the hydrophilic stroma.

Question 12: Which treatment is considered the gold standard for anisometropic amblyopia?

Immediate patching before refractive correction
Surgical realignment of the eyes
Vision therapy alone without refractive correction
Full refractive correction followed by patching or atropine penalization of the fellow eye (Correct answer)

Correct answer: Full refractive correction followed by patching or atropine penalization of the fellow eye

Full refractive correction must be provided first; many children with anisometropic amblyopia improve with glasses alone, and patching or atropine is added if improvement plateaus.

Question 13: Extended wear contact lenses are most associated with which serious complication?

Superior epithelial arcuate lesions
Microbial keratitis (Correct answer)
Contact lens-induced acute red eye
Giant papillary conjunctivitis

Correct answer: Microbial keratitis

Extended (overnight) wear dramatically increases the risk of microbial keratitis, particularly from Pseudomonas aeruginosa and Acanthamoeba.

Question 14: The optic nerve is surrounded by an extension of which meningeal layer that forms the optic nerve sheath?

Arachnoid mater only
Pia mater only
All three meningeal layers (Correct answer)
Dura mater only

Correct answer: All three meningeal layers

The optic nerve is surrounded by all three meningeal layers—dura, arachnoid, and pia mater—which form the optic nerve sheaths and are continuous with the brain meninges.

Question 15: Astigmatism is defined as a refractive condition in which:

The eye has different powers in different meridians (Correct answer)
The cornea is uniformly too steep for the axial length
The eye has no definite focal point
Both eyes have equal refractive errors

Correct answer: The eye has different powers in different meridians

Astigmatism occurs when the refracting surfaces of the eye have different curvatures in different meridians, preventing parallel rays from converging to a single point focus.

Question 16: What is the primary purpose of professional liability insurance for optometrists?

To insure the building against natural disasters
To provide health benefits to employees
To cover office equipment
To protect against claims of negligence or malpractice (Correct answer)

Correct answer: To protect against claims of negligence or malpractice

Professional liability insurance, also known as malpractice insurance, protects optometrists from lawsuits alleging negligence or errors in patient care.

Question 17: Which systemic condition is most associated with neovascular glaucoma and requires co-management with optometry?

Diabetes mellitus with proliferative diabetic retinopathy (Correct answer)
Hyperthyroidism with thyroid eye disease
Anemia with retinal vascular dilation
Hypertension with retinal arteriolar changes

Correct answer: Diabetes mellitus with proliferative diabetic retinopathy

PDR causes widespread retinal ischemia that releases VEGF, driving neovascularization of the iris and angle — leading to the most refractory form of glaucoma.

Question 18: In subjective refraction, the Jackson cross-cylinder (JCC) is used primarily to:

Determine the sphere power endpoint
Measure the AC/A ratio
Refine the cylinder axis and power (Correct answer)
Screen for color deficiency

Correct answer: Refine the cylinder axis and power

The JCC is a combination of equal plus and minus cylinders 90° apart; flipping it tests whether rotating the cylinder axis or changing its power improves clarity.

Question 19: Which lens aberration causes peripheral blur and is addressed by aspheric lens designs?

Spherical aberration along the optical axis
Oblique astigmatism (marginal astigmatism) (Correct answer)
Coma
Chromatic aberration

Correct answer: Oblique astigmatism (marginal astigmatism)

Oblique astigmatism occurs when oblique rays through the peripheral lens produce different focal distances in the sagittal and tangential planes, causing peripheral distortion corrected by aspheric designs.

Question 20: Binasal occlusion in prism glasses is used to treat which binocular vision condition?

Alternating exotropia
Esophoria with high AC/A ratio
Exophoria with convergence insufficiency (Correct answer)
Accommodative esotropia

Correct answer: Exophoria with convergence insufficiency

Binasal occlusion reduces peripheral fusion disruption and enhances accommodative convergence in patients with exophoric tendencies and convergence insufficiency.

Question 21: Electronic magnification devices (CCTV or video magnifiers) offer which advantage over optical magnifiers?

Better for patients with central field loss than peripheral loss
No power source required for portability
Variable magnification, enhanced contrast, and reverse polarity viewing (Correct answer)
Higher maximum magnification than all optical devices

Correct answer: Variable magnification, enhanced contrast, and reverse polarity viewing

Video magnifiers allow continuous variable magnification, high-contrast display modes, and white-on-black reverse polarity, which optical magnifiers cannot provide.

Question 22: Pseudoexfoliation syndrome is associated with which significant systemic risk?

Cardiovascular disease and increased risk of myocardial infarction (Correct answer)
Type 2 diabetes and metabolic syndrome
Increased risk of stroke only
No significant systemic associations

Correct answer: Cardiovascular disease and increased risk of myocardial infarction

Pseudoexfoliation syndrome is now recognized as a systemic fibrillopathy associated with elevated cardiovascular risk, including myocardial infarction and aortic aneurysm.

Question 23: Bitemporal hemianopia is most commonly caused by a lesion at which anatomical location?

Lateral geniculate nucleus
Optic tract
Optic chiasm (Correct answer)
Occipital cortex

Correct answer: Optic chiasm

Bitemporal hemianopia results from compression of the crossing nasal fibers at the optic chiasm, most often by a pituitary adenoma.

Question 24: Normal tension glaucoma (NTG) is characterized by glaucomatous optic nerve damage occurring with:

IOP consistently within the statistically normal range (≤21 mmHg) (Correct answer)
Extremely elevated IOP above 30 mmHg
Anterior chamber angle closure
Pigment dispersion into the trabecular meshwork

Correct answer: IOP consistently within the statistically normal range (≤21 mmHg)

NTG shows progressive glaucomatous optic nerve damage and visual field loss despite IOP never exceeding the statistical upper limit of normal, suggesting pressure-independent mechanisms.

Question 25: Which topical anesthetic is most commonly used for tonometry in optometric practice?

Cocaine 4%
Lidocaine 2%
Tetracaine 1%
Proparacaine 0.5% (Correct answer)

Correct answer: Proparacaine 0.5%

Proparacaine 0.5% is the most widely used topical ophthalmic anesthetic due to its rapid onset, short duration, and minimal stinging compared to other agents.

Question 26: What is the main treatment for amblyopia in children?

Patching the stronger eye (Correct answer)
Eye exercises
Eyeglasses
Surgery

Correct answer: Patching the stronger eye

Patching the stronger eye is a common treatment for amblyopia to force the brain to use the weaker eye, thereby strengthening it.

Question 27: Which choroidal tumor appears as an orange-red elevated lesion on fundoscopy and is the most common primary intraocular malignancy in adults?

Retinoblastoma
Metastatic carcinoma
Uveal melanoma (Correct answer)
Choroidal hemangioma

Correct answer: Uveal melanoma

Uveal melanoma is the most common primary intraocular malignancy in adults and typically appears as a pigmented choroidal mass.

Question 28: In low vision rehabilitation, a stand magnifier is preferred over a hand magnifier when a patient has:

Good distance acuity but reduced near acuity only
Tremor or limited hand dexterity affecting stable holding (Correct answer)
Mild low vision needing less than 4× magnification
Need for portability and variable focal distance

Correct answer: Tremor or limited hand dexterity affecting stable holding

Stand magnifiers rest on the page at a fixed focal distance, eliminating the need to maintain precise working distance — ideal for patients with tremor or arthritis.

Question 29: Contrast sensitivity testing is important in geriatric optometry because:

It detects functional vision loss not captured by Snellen acuity (Correct answer)
It measures the amplitude of accommodation accurately
It screens for color blindness in elderly patients
It determines the need for anti-reflective coatings only

Correct answer: It detects functional vision loss not captured by Snellen acuity

Contrast sensitivity (CS) decline is common in aging and early cataracts/AMD and can significantly impair functional vision even when Snellen acuity is near-normal.

Question 30: The mechanism of cyclopentolate in achieving cycloplegia differs from atropine primarily in its:

Lack of pupillary dilation
Duration of action (shorter: 24 hours vs. 7–14 days) (Correct answer)
Mechanism of receptor blockade (nicotinic vs. muscarinic)
Effect on aqueous production

Correct answer: Duration of action (shorter: 24 hours vs. 7–14 days)

Both cyclopentolate and atropine are anticholinergic (muscarinic) agents, but cyclopentolate's cycloplegia lasts ~24 hours versus atropine's 7–14 days.

Question 31: Pilocarpine is used in acute angle-closure glaucoma attack management to:

Dilate the pupil to reopen the drainage angle
Contract the iris sphincter to pull the peripheral iris from the angle (Correct answer)
Lubricate the trabecular meshwork
Reduce aqueous production in the ciliary body

Correct answer: Contract the iris sphincter to pull the peripheral iris from the angle

Pilocarpine (a muscarinic agonist) constricts the pupil, mechanically pulling the peripheral iris tissue away from the trabecular meshwork to re-open the drainage angle during an acute attack.

Question 32: What is the purpose of vision therapy in pediatric optometry?

To correct refractive errors
To improve visual skills and processing (Correct answer)
To treat eye infections
To remove cataracts

Correct answer: To improve visual skills and processing

Vision therapy is used to enhance the visual system, improving skills such as eye tracking, focusing, and coordination.

Question 33: Which type of insurance is essential for optometrists to cover potential claims of discrimination or wrongful termination from employees?

Health insurance
Vision insurance
Employment practices liability insurance (Correct answer)
Professional liability insurance

Correct answer: Employment practices liability insurance

Employment practices liability insurance protects against claims made by employees for issues such as discrimination, wrongful termination, and harassment.

Question 34: Which of the following is typically included in an optometrist's business owner's policy (BOP)?

Property insurance and general liability insurance (Correct answer)
Vision insurance
Health insurance
Workers' compensation insurance

Correct answer: Property insurance and general liability insurance

A business owner's policy typically includes property insurance and general liability insurance, covering physical assets and general business liabilities.

Question 35: Why is it important for optometrists to verify a patient's insurance benefits before providing services?

To establish a diagnosis
To ensure payment for services rendered (Correct answer)
To determine the patient's medical history
To schedule follow-up appointments

Correct answer: To ensure payment for services rendered

Verifying insurance benefits ensures that the services provided will be covered by the patient's insurance plan, minimizing the risk of non-payment.

Question 36: Accommodative esotropia is most effectively treated initially with:

Prism in the glasses to neutralize the deviation
Surgical recession of the medial rectus
Patching of the non-dominant eye
Full cycloplegic refraction and spectacle correction (Correct answer)

Correct answer: Full cycloplegic refraction and spectacle correction

Accommodative esotropia is caused by uncorrected hyperopia driving excess accommodation-convergence; providing the full hyperopic correction reduces or eliminates the convergent deviation.

Question 37: What is the primary purpose of the 'fitting cross' used in multifocal soft contact lens evaluation?

To verify the optical power of the reading zone
To determine the appropriate base curve for the lens
To measure corneal toricity with a keratometer
To assess centration and zone alignment relative to the pupil (Correct answer)

Correct answer: To assess centration and zone alignment relative to the pupil

The fitting cross marking on multifocal lenses helps the practitioner verify that the distance and near optical zones are appropriately centered over the pupil.

Question 38: The central retinal artery is a branch of which vessel?

Ophthalmic artery (Correct answer)
Anterior ciliary artery
Posterior ciliary artery
Internal carotid artery

Correct answer: Ophthalmic artery

The central retinal artery is a branch of the ophthalmic artery, which itself is the first branch of the internal carotid artery.

Question 39: Orthokeratology (ortho-K) lenses work primarily by:

Reducing aqueous production
Surgically flattening the stroma
Reshaping the corneal epithelium during overnight wear (Correct answer)
Increasing corneal thickness centrally

Correct answer: Reshaping the corneal epithelium during overnight wear

Ortho-K uses reverse geometry RGP lenses worn overnight to temporarily flatten the central corneal epithelium, reducing myopia during the day.

Question 40: When performing the duochrome (bichrome) test, if both red and green appear equally clear, the endpoint indicates:

The patient has color deficiency
The patient is myopic and needs more minus
The patient has astigmatism requiring cylinder
The refractive correction is optimally balanced (best sphere endpoint) (Correct answer)

Correct answer: The refractive correction is optimally balanced (best sphere endpoint)

Equal clarity of red and green targets means the circle of least confusion is on the retina, placing the patient at the optimal spherical endpoint for their chromatic aberration.

Question 41: When fitting toric soft contact lenses, the lens should rotate to the:

Correct orientation as marked by the stabilization ballast (Correct answer)
Lower lid position to allow blink-driven rotation
Superior limbus for maximum stability
Nasal position regardless of the prescription

Correct answer: Correct orientation as marked by the stabilization ballast

Toric lenses use prism ballast or peri-ballast stabilization to maintain axis orientation; correct on-eye position is verified by the lens markings aligning with the intended axis.

Question 42: Strabismus surgery for constant exotropia primarily aims to:

Correct the refractive error causing the deviation
Improve visual acuity in the amblyopic eye
Realign the visual axes to restore binocular vision potential (Correct answer)
Reduce intraocular pressure in the affected eye

Correct answer: Realign the visual axes to restore binocular vision potential

Strabismus surgery repositions the extraocular muscles to realign the eyes, creating the opportunity for binocular fusion and stereopsis to develop or be restored.

Question 43: Amsler grid testing is used to monitor which functional change in patients with macular disease?

Peripheral visual field constriction
Color vision deficiency
Intraocular pressure changes
Metamorphopsia and central scotomas (Correct answer)

Correct answer: Metamorphopsia and central scotomas

The Amsler grid detects metamorphopsia (line waviness/distortion) and scotomas (missing areas) in the central 20° of visual field, useful for monitoring AMD progression.

Question 44: What is the primary role of a third-party administrator in relation to vision insurance plans?

To conduct eye exams
To sell insurance policies
To provide legal advice
To manage and process insurance claims (Correct answer)

Correct answer: To manage and process insurance claims

A third-party administrator handles the administration of insurance plans, including processing claims and managing benefits.

Question 45: A patient reports seeing double only when looking to the left. This pattern suggests:

Paresis of a left-gaze muscle in one eye (Correct answer)
Primary position exophoria
Bilateral superior oblique palsy
Monocular diplopia

Correct answer: Paresis of a left-gaze muscle in one eye

Binocular diplopia that occurs only in one direction of gaze localizes to the muscle(s) responsible for that gaze direction, suggesting a paretic strabismus.

Question 46: Which of the following is typically not covered by standard vision insurance?

Eye exams
Contact lenses
Surgical procedures (Correct answer)
Prescription glasses

Correct answer: Surgical procedures

Vision insurance usually covers routine eye care but not surgical procedures, which are typically covered by health insurance.

Question 47: A branch retinal artery occlusion most commonly appears on fundoscopy as:

Pigment clumping in the periphery
Disc neovascularization
A wedge-shaped area of retinal whitening (Correct answer)
Dot-and-blot hemorrhages along the arcades

Correct answer: A wedge-shaped area of retinal whitening

Branch retinal artery occlusion causes acute ischemic edema appearing as a wedge of opaque, whitened (infarcted) retina in the distribution of the occluded vessel.

Question 48: Convergence insufficiency is best defined as:

Intermittent exotropia greater at distance
Reduced near point of convergence and low positive fusional vergence at near (Correct answer)
Esophoria at near with high AC/A ratio
Reduced amplitude of accommodation at near

Correct answer: Reduced near point of convergence and low positive fusional vergence at near

CI is diagnosed by a receded near point of convergence (>6–8 cm) combined with reduced positive fusional vergence reserves at near and associated asthenopic symptoms.

Question 49: The critical period for amblyopia treatment is generally considered to close around:

12–14 years of age
18 years of age
7–9 years of age (Correct answer)
2–3 years of age

Correct answer: 7–9 years of age

The visual cortex retains neuroplasticity for amblyopia treatment most effectively up to age 7–9, though some response is possible into adolescence with intensive treatment.

Question 50: Which insurance is required by law for most employers to provide to their employees, covering work-related injuries and illnesses?

Workers' compensation insurance (Correct answer)
Professional liability insurance
Vision insurance
Health insurance

Correct answer: Workers' compensation insurance

Workers' compensation insurance is mandated by law to provide benefits to employees who suffer work-related injuries or illnesses.

Question 51: Central geographic atrophy of the retinal pigment epithelium is a hallmark of which condition?

Dry age-related macular degeneration (Correct answer)
Stargardt disease
Central serous chorioretinopathy
Wet age-related macular degeneration

Correct answer: Dry age-related macular degeneration

Geographic atrophy of the RPE is the advanced form of dry (atrophic) AMD, leading to progressive central vision loss.

Question 52: The most significant risk factor for falls in elderly low vision patients is:

Reduced contrast sensitivity and peripheral field loss (Correct answer)
Reduced near acuity below 20/200
Myopia greater than 6 diopters
Presence of astigmatism above 1.50D

Correct answer: Reduced contrast sensitivity and peripheral field loss

Contrast sensitivity loss impairs detection of steps and curbs, while peripheral field loss reduces obstacle detection — both are major fall risk factors in elderly patients.

Question 53: Which lens care system is contraindicated for use with silicone hydrogel lenses due to corneal staining?

Certain preserved multipurpose solutions (MPS) containing PHMB or Alexidine (Correct answer)
Hydrogen peroxide systems
Preservative-free unit-dose saline
Saline-only rinsing solutions

Correct answer: Certain preserved multipurpose solutions (MPS) containing PHMB or Alexidine

Some MPS formulations containing PHMB or Alexidine interact with silicone hydrogel materials, causing preservative binding that leads to toxic epithelial staining.

Question 54: Polypharmacy in elderly patients is relevant to optometry because:

Most systemic drugs improve intraocular pressure control
Polypharmacy has no relationship to ocular conditions
Many systemic medications cause ocular side effects including dry eye, angle changes, and lens toxicity (Correct answer)
Older patients are less susceptible to topical drug side effects

Correct answer: Many systemic medications cause ocular side effects including dry eye, angle changes, and lens toxicity

Numerous systemic medications (amiodarone, tamsulosin, hydroxychloroquine, steroids) have significant ocular side effects that the optometrist must screen for during comprehensive exams.

Question 55: Eccentric viewing training in low vision rehabilitation teaches a patient to:

Use a preferred retinal locus outside the damaged macula (Correct answer)
Improve contrast sensitivity with optical aids
Increase fixation stability in the fovea
Expand the peripheral visual field artificially

Correct answer: Use a preferred retinal locus outside the damaged macula

Eccentric viewing trains patients with central scotomas to consistently fixate using a healthy para-central preferred retinal locus (PRL) to maximize functional vision.

Question 56: Which class of drugs is specifically contraindicated with topical pilocarpine due to risk of cholinergic toxicity?

Topical beta-blockers
Topical prostaglandin analogs
Systemic cholinesterase inhibitors (e.g., echothiophate iodide) (Correct answer)
Systemic carbonic anhydrase inhibitors

Correct answer: Systemic cholinesterase inhibitors (e.g., echothiophate iodide)

Echothiophate (an irreversible cholinesterase inhibitor) combined with pilocarpine produces additive muscarinic stimulation; echothiophate also prolongs succinylcholine-induced apnea in surgery.

Question 57: Which layer of the cornea is responsible for its transparency and makes up approximately 90% of corneal thickness?

Bowman's layer
Stroma (Correct answer)
Descemet's membrane
Epithelium

Correct answer: Stroma

The stroma constitutes about 90% of the cornea's thickness and is composed of regularly arranged collagen lamellae that contribute directly to corneal transparency.

Question 58: What type of insurance would cover the cost of replacing expensive ophthalmic equipment damaged by a fire?

Professional liability insurance
Workers' compensation insurance
Vision insurance
Property insurance (Correct answer)

Correct answer: Property insurance

Property insurance covers the loss or damage to business property, including ophthalmic equipment, due to events like fire.

Question 59: Which ocular finding is pathognomonic for ocular hypertension secondary to pseudoexfoliation syndrome?

Flaky white material on the lens capsule (Correct answer)
Corneal guttata
Posterior subcapsular cataract
Band keratopathy

Correct answer: Flaky white material on the lens capsule

Pseudoexfoliation syndrome is characterized by dandruff-like fibrillar material deposited on the anterior lens capsule and other anterior segment structures.

Question 60: Which clinical finding is most characteristic of keratoconus?

Corneal arcus with lipid deposits
Bilateral corneal ulceration
Irregular corneal thinning and steepening (Correct answer)
Diffuse corneal edema

Correct answer: Irregular corneal thinning and steepening

Keratoconus is defined by progressive stromal thinning and ectasia (forward cone-shaped bulging) of the cornea causing irregular astigmatism.

Question 61: Rubeosis iridis (neovascularization of the iris) is a complication most associated with which condition?

Phlyctenular keratoconjunctivitis
Primary open-angle glaucoma
Fuchs' endothelial dystrophy
Central retinal vein occlusion (Correct answer)

Correct answer: Central retinal vein occlusion

Central retinal vein occlusion causes widespread retinal ischemia that can stimulate VEGF-driven neovascularization of the iris, leading to neovascular glaucoma.

Question 62: Which type of diabetic retinopathy is characterized by the presence of new blood vessel formation?

Non-proliferative diabetic retinopathy
Background retinopathy
Preproliferative retinopathy
Proliferative diabetic retinopathy (Correct answer)

Correct answer: Proliferative diabetic retinopathy

Proliferative diabetic retinopathy (PDR) is defined by the growth of new, abnormal blood vessels (neovascularization) on the retinal surface.

Question 63: Acanthamoeba keratitis is uniquely associated with which contact lens behavior?

Sleeping in daily disposable lenses
Rinsing lenses with tap water or swimming while wearing lenses (Correct answer)
Using expired lens care solutions
Over-wearing annual replacement lenses

Correct answer: Rinsing lenses with tap water or swimming while wearing lenses

Acanthamoeba is a waterborne protozoan; exposure through tap water rinsing or water sports creates the primary risk for this difficult-to-treat corneal infection.

Question 64: Amblyopia is defined as reduced best-corrected visual acuity in one or both eyes due to:

Refractive error alone that cannot be corrected with glasses
Intraocular pressure damage to the optic nerve
Structural abnormality of the retina or optic nerve
Abnormal visual experience during the critical period of development (Correct answer)

Correct answer: Abnormal visual experience during the critical period of development

Amblyopia is a neurodevelopmental condition caused by abnormal visual input (deprivation, strabismus, or anisometropia) during the sensitive period, leading to cortical suppression.

Question 65: Superior epithelial arcuate lesions (SEALs) in soft contact lens wearers are located at:

Central corneal epithelium
Nasal bulbar conjunctiva
Superior limbal region, parallel to the limbus (Correct answer)
Inferior cornea at the lens edge

Correct answer: Superior limbal region, parallel to the limbus

SEALs are non-infective, sterile epithelial splits at the superior limbus caused by mechanical interaction of the lens edge with the superior limbal epithelium under the upper lid.

Question 66: With-the-rule astigmatism is defined as when:

Both principal meridians are oblique
The astigmatism is irregular and cannot be corrected with cylinders
The steepest corneal meridian is vertical (near 90°) (Correct answer)
The steepest corneal meridian is horizontal (near 180°)

Correct answer: The steepest corneal meridian is vertical (near 90°)

With-the-rule (WTR) astigmatism has maximum corneal power vertically (90°±30°), which is the most common pattern in children and young adults.

Question 67: Which of the following is a common refractive error in children?

Glaucoma
Myopia (Correct answer)
Cataracts
Macular degeneration

Correct answer: Myopia

Myopia (nearsightedness) is a common refractive error in children where distant objects appear blurry.

Question 68: The Purkinje-Sanson images are reflections from the four surfaces of the eye used to:

Calibrate retinoscopy findings
Determine the anterior chamber depth
Measure corneal curvature with a keratometer
Locate the position of the crystalline lens and assess its clarity (Correct answer)

Correct answer: Locate the position of the crystalline lens and assess its clarity

The four Purkinje-Sanson images are virtual reflections from the anterior cornea, posterior cornea, anterior lens, and posterior lens, used historically to locate the lens and detect cataracts.

Question 69: What is amblyopia commonly known as?

Night blindness
Color blindness
Double vision
Lazy eye (Correct answer)

Correct answer: Lazy eye

Amblyopia, commonly known as lazy eye, is a developmental problem in the brain, not the eye itself, resulting in poor vision in one eye.

Question 70: Fluorescein dye in optometric practice is used primarily for:

Constricting the pupil before laser procedures
Dilating the pupil for fundus examination
Applanation tonometry and contact lens fitting evaluation (Correct answer)
Treating bacterial corneal ulcers

Correct answer: Applanation tonometry and contact lens fitting evaluation

Fluorescein sodium is a vital dye that fluoresces yellow-green under cobalt blue illumination, used to assess the tear film, fit RGP lenses, and measure IOP by applanation.

Question 71: Silicone hydrogel lenses have largely replaced conventional hydrogel lenses because they offer:

Reduced UV exposure to the cornea
Higher oxygen permeability with similar or better comfort (Correct answer)
Lower modulus of elasticity
Greater resistance to lipid deposits

Correct answer: Higher oxygen permeability with similar or better comfort

Silicone hydrogel materials achieve Dk values 5–6× higher than conventional hydrogels, reducing hypoxic complications while maintaining wearable comfort.

Question 72: Giant papillary conjunctivitis (GPC) in contact lens wearers is best managed by:

Switching to daily disposable lenses and reducing wear time (Correct answer)
Switching to higher water content soft lenses
Prescribing topical antibiotic drops
Increasing lens replacement frequency to monthly

Correct answer: Switching to daily disposable lenses and reducing wear time

GPC is an immunological response to lens deposits and mechanical trauma; daily disposables eliminate deposit accumulation and reduce antigenic load.

Question 73: Oral acetazolamide (Diamox) used for acute IOP reduction works by inhibiting which enzyme?

Carbonic anhydrase, reducing bicarbonate-driven aqueous secretion (Correct answer)
HMG-CoA reductase, reducing episcleral venous pressure
Cholinesterase, increasing trabecular outflow
Cyclooxygenase, reducing prostaglandin-mediated inflammation

Correct answer: Carbonic anhydrase, reducing bicarbonate-driven aqueous secretion

Acetazolamide inhibits carbonic anhydrase throughout the body, with the dominant ocular effect being reduced bicarbonate and sodium co-transport by the ciliary epithelium, cutting aqueous production by 40–60%.

Question 74: When transposing a spectacle prescription from plus cylinder to minus cylinder form, which step is performed LAST?

Divide the sphere by the cylinder to find the new axis
Add sphere and cylinder together to get the new sphere
Keep the old axis and just change the sphere power
Change the sign of the cylinder while keeping the magnitude the same, and rotate the axis by 90° (Correct answer)

Correct answer: Change the sign of the cylinder while keeping the magnitude the same, and rotate the axis by 90°

Transposition steps are: (1) algebraically add sphere and cylinder to get new sphere; (2) change the sign of the cylinder; (3) rotate the axis by 90° — the axis change is the final step.

Question 75: The primary goal of vision therapy for convergence insufficiency is to:

Eliminate the need for reading glasses
Improve convergence amplitude and fusional vergence ranges (Correct answer)
Strengthen extraocular muscles surgically
Correct the refractive error causing asthenopia

Correct answer: Improve convergence amplitude and fusional vergence ranges

Vision therapy for CI aims to recondition the neuromuscular control of convergence, increasing both the amplitude and the positive fusional vergence reserves.

Question 76: What is the FDA oxygen transmissibility threshold for extended-wear soft contact lenses?

Dk/t ≥ 24 ISO units
Dk/t ≥ 125 ISO units
Dk/t ≥ 87 ISO units (Correct answer)
Dk/t ≥ 50 ISO units

Correct answer: Dk/t ≥ 87 ISO units

The FDA requires a minimum Dk/t of 87 ISO units for extended-wear (up to 30 nights) soft contact lens approval to support adequate corneal oxygenation.

Question 77: Scleral contact lenses differ from corneal RGP lenses primarily because they:

Vault the entire cornea and rest on the sclera (Correct answer)
Have higher water content than soft lenses
Are designed for daily disposable use only
Are softer and conform to the corneal shape

Correct answer: Vault the entire cornea and rest on the sclera

Scleral lenses have a large diameter (>18 mm) that vaults the cornea completely and lands on the scleral tissue, holding a fluid reservoir over the cornea.

Question 78: Which extraocular muscle is responsible for intorsion of the eye when it is in the primary position?

Superior rectus
Medial rectus
Inferior oblique
Superior oblique (Correct answer)

Correct answer: Superior oblique

The superior oblique's primary action in the primary position is intorsion (incycloduction), with secondary actions of depression and abduction.

Question 79: What is the benefit of having an umbrella insurance policy in addition to primary insurance coverage for an optometric practice?

It replaces the need for professional liability insurance
It increases the coverage limits beyond the primary policy (Correct answer)
It provides health benefits to employees
It covers only routine eye exams

Correct answer: It increases the coverage limits beyond the primary policy

An umbrella insurance policy provides additional coverage limits beyond those of the primary insurance policies, offering extra protection against large claims.

Question 80: Prostaglandin analogs (e.g., latanoprost) lower intraocular pressure by:

Increasing aqueous outflow through the uveoscleral pathway (Correct answer)
Decreasing aqueous production by the ciliary body
Increasing conventional trabecular outflow only
Constricting the pupil to open the drainage angle

Correct answer: Increasing aqueous outflow through the uveoscleral pathway

Prostaglandin analogs primarily enhance uveoscleral (non-conventional) aqueous outflow by remodeling the ciliary body extracellular matrix, reducing IOP by 25–35%.

Question 81: The fovea centralis is specialized for high-acuity vision primarily because it contains a high density of which cell type?

Amacrine cells
Horizontal cells
Cone photoreceptors (Correct answer)
Rods

Correct answer: Cone photoreceptors

The fovea has the highest density of cone photoreceptors and lacks rods, providing maximum visual acuity and color discrimination.

Question 82: Systemic side effects of topical phenylephrine 10% include:

Bradycardia and bronchospasm
Urinary retention and constipation
Hypoglycemia and sedation
Hypertension and tachycardia due to systemic absorption (Correct answer)

Correct answer: Hypertension and tachycardia due to systemic absorption

Phenylephrine 10% can be absorbed systemically via nasolacrimal drainage, stimulating alpha-1 receptors to cause hypertension, sometimes severe, especially in elderly patients.

Question 83: The power of a thin lens required to correct a 4D myope is:

-4.00 D (Correct answer)
+4.00 D
+2.00 D
-2.00 D

Correct answer: -4.00 D

To move the far point from 25 cm in front of the eye to optical infinity, a diverging lens of -4.00 D (focal length -25 cm) is required.

Question 84: The aqueous humor is primarily produced by which ocular structure?

Schlemm's canal
Ciliary body epithelium (Correct answer)
Trabecular meshwork
Iris pigment epithelium

Correct answer: Ciliary body epithelium

The non-pigmented epithelium of the ciliary body actively secretes aqueous humor into the posterior chamber.

Question 85: When performing retinoscopy, a 'with' reflex indicates that the eye's far point is:

At the examiner's working distance (neutrality)
Unrelated to the far point location
In front of the examiner (high myopia)
Behind the examiner (hyperopia or low myopia) (Correct answer)

Correct answer: Behind the examiner (hyperopia or low myopia)

A 'with' motion reflex during retinoscopy means the far point is beyond the examiner's working distance, indicating hyperopia or myopia less than the working lens.

Question 86: Age-related changes to the accommodative system include all of the following EXCEPT:

Reduced ciliary muscle contractility
Increased lens nuclear sclerosis
Reduction in corneal refractive power (Correct answer)
Hardening of the crystalline lens nucleus

Correct answer: Reduction in corneal refractive power

Presbyopia is caused by lens nuclear hardening, reduced ciliary muscle efficiency, and lens capsule changes — corneal curvature is not a significant factor in presbyopia development.

Question 87: Low vision rehabilitation is indicated when a patient's best-corrected visual acuity is:

20/200 or worse in the worse eye only
20/40 in both eyes with night blindness
20/20 with significant contrast sensitivity loss only
20/70 or worse in the better eye with reduced functional ability (Correct answer)

Correct answer: 20/70 or worse in the better eye with reduced functional ability

Low vision rehabilitation is appropriate for patients with best-corrected VA of 20/70 or worse that limits daily functioning and cannot be further improved by optical correction or treatment.

Question 88: The far point of a +3.00 D corrected hyperope (corrected at far) is located:

At optical infinity
33 cm behind the eye (virtual far point) (Correct answer)
33 cm in front of the eye
6 meters behind the eye

Correct answer: 33 cm behind the eye (virtual far point)

In uncorrected hyperopia, the far point is virtual (behind the eye); for a 3D hyperope, the far point is 1/3 m = 33 cm posterior to the eye, requiring a converging beam.

Question 89: A patient presents with sudden onset of a dark curtain moving across their vision. Which condition is most likely?

Central retinal vein occlusion
Vitreous hemorrhage
Retinal detachment (Correct answer)
Optic neuritis

Correct answer: Retinal detachment

A shadow or curtain moving across the visual field is the classic symptom of rhegmatogenous retinal detachment.

Question 90: The vertex distance is clinically important because:

It affects the prism power at the lens periphery
Changing it alters the effective power of high-powered lenses (Correct answer)
It changes the chromatic aberration of the lens
It determines the axis of a cylindrical correction

Correct answer: Changing it alters the effective power of high-powered lenses

The effective power of a lens changes with vertex distance; for powers >±4D, failure to account for vertex distance during refraction and dispensing introduces clinically significant error.

Question 91: What is the recommended age for a child's first comprehensive eye examination according to the American Optometric Association?

At birth
At 2 years
At 5 years
At 6 months (Correct answer)

Correct answer: At 6 months

The AOA recommends that infants have their first comprehensive eye examination at 6 months of age to detect any potential vision problems early.

Question 92: Contact lens-induced corneal neovascularization is primarily caused by:

Chronic corneal hypoxia stimulating VEGF release (Correct answer)
Protein deposits on the lens surface
Solution sensitivity reaction
Mechanical trauma from lens edge

Correct answer: Chronic corneal hypoxia stimulating VEGF release

Sustained corneal hypoxia triggers VEGF upregulation, stimulating vessel growth from the limbus into the normally avascular cornea.

Question 93: The minimum add power for a presbyopic patient is determined by:

The patient's age divided by 10
The near point of convergence distance
The patient's distance refractive error alone
The amplitude of accommodation minus the required near demand reserve (Correct answer)

Correct answer: The amplitude of accommodation minus the required near demand reserve

The add is calculated so that after the add, the patient still uses only about half their remaining accommodation for comfortable sustained near work (Donder's rule of reserve).

Question 94: The principal effect of a minus cylinder lens is to:

Reduce power equally in all meridians
Reduce power in one meridian while leaving the other unchanged (Correct answer)
Rotate the axis of astigmatism by 90°
Increase power equally in all meridians

Correct answer: Reduce power in one meridian while leaving the other unchanged

A minus cylinder lens has zero power along its axis meridian and maximum minus power 90° away, selectively reducing power in one meridian.

Question 95: A patient with moderate AMD and an absolute central scotoma should first be trained to use:

Laser pointer exercises to stimulate foveal recovery
A pair of bioptic telescopes for all tasks
A high-power plus add spectacle lens at standard working distance
An eccentric viewing technique with a preferred retinal locus (Correct answer)

Correct answer: An eccentric viewing technique with a preferred retinal locus

When the fovea is destroyed, rehabilitation begins with identifying and training a stable PRL in the peri-central retina for fixation and visual tasks.

Question 96: Which fitting relationship describes a rigid gas-permeable (RGP) lens that is steeper than the corneal curvature?

Steep (vaulting) fit (Correct answer)
Flat fit
Interpalpebral fit
Alignment fit

Correct answer: Steep (vaulting) fit

When a RGP lens base curve is steeper than the flattest corneal meridian (K), the lens vaults the cornea and causes apical clearance.

Question 97: Which mydriatic agent is preferred for fundus examination in pediatric patients due to its shorter duration?

Tropicamide 0.5–1% (Correct answer)
Atropine 1%
Phenylephrine 10%
Scopolamine 0.25%

Correct answer: Tropicamide 0.5–1%

Tropicamide has a short duration (4–8 hours) making it practical for routine dilation, while atropine's 7–14 day effect is reserved for cycloplegic refraction when needed.

Question 98: A patient with 4th cranial nerve palsy would show which characteristic ocular deviation?

Hypotropia in all positions of gaze
Esotropia greater at near than at distance
Hypertropia that worsens with contralateral head tilt (Correct answer)
Exotropia in primary position

Correct answer: Hypertropia that worsens with contralateral head tilt

Fourth nerve (trochlear) palsy causes ipsilateral superior oblique paresis, producing a hypertropia that worsens when tilting the head toward the affected side (Bielschowsky head tilt test).

Question 99: In an eye with simple myopia, the far point is located:

On the retina itself
At optical infinity behind the retina
At a finite distance in front of the eye (Correct answer)
At the anterior focal point of the eye

Correct answer: At a finite distance in front of the eye

In myopia the parallel rays from infinity focus in front of the retina; the far point (where diverging rays appear to come from) is at a finite real distance anterior to the eye.

Question 100: Retinitis pigmentosa classically causes which pattern of visual field loss?

Altitudinal defect
Central scotoma
Ring scotoma with peripheral constriction (Correct answer)
Bitemporal hemianopia

Correct answer: Ring scotoma with peripheral constriction

RP causes progressive degeneration of peripheral rods first, producing ring scotomas that expand to cause tunnel vision over time.

Question 101: The Maddox rod test is used primarily to assess:

Contrast sensitivity
Stereoacuity at near and distance
The type and magnitude of a phoria (Correct answer)
Visual field defects

Correct answer: The type and magnitude of a phoria

The Maddox rod dissociates binocular fusion and converts one eye's point light source into a streak, allowing the clinician to measure the latent phoria direction and magnitude with a prism bar.

Question 102: Brimonidine (alpha-2 agonist) lowers IOP through which dual mechanism?

Increasing trabecular outflow only
Blocking muscarinic receptors in ciliary body
Decreasing uveoscleral outflow only
Decreasing aqueous production AND increasing uveoscleral outflow (Correct answer)

Correct answer: Decreasing aqueous production AND increasing uveoscleral outflow

Brimonidine stimulates alpha-2 adrenergic receptors to both decrease aqueous production (reduced cAMP) and increase uveoscleral outflow, achieving a 20–25% IOP reduction.

Question 103: Driving cessation recommendations for visually impaired elderly patients should include which statement?

All patients over age 75 should stop driving regardless of visual acuity
Monocular patients with 20/20 in one eye have no driving restrictions
Patients with BCVA worse than 20/40 in the better eye typically do not meet US driving standards (Correct answer)
Night driving is acceptable as long as daytime acuity is 20/20

Correct answer: Patients with BCVA worse than 20/40 in the better eye typically do not meet US driving standards

Most US state driving standards require minimum acuity of 20/40 in the better eye; patients below this threshold should be counseled about driving cessation and alternative transportation.

Question 104: Which condition is a primary indication for fitting a patient with rigid gas-permeable lenses instead of soft lenses?

Low myopia with no astigmatism
High water loss dry eye syndrome
History of giant papillary conjunctivitis
Keratoconus with irregular astigmatism (Correct answer)

Correct answer: Keratoconus with irregular astigmatism

RGP lenses mask irregular corneal surface and provide superior optical quality for keratoconus patients, unlike soft lenses that drape the irregular surface.

Question 105: How often should school-aged children have their eyes examined if they do not have any visual problems?

Every two years (Correct answer)
Annually
Every 6 months
Only when they experience vision problems

Correct answer: Every two years

The AOA recommends that school-aged children without vision problems have their eyes examined every two years to monitor and maintain eye health.

Question 106: The 'sunset glow fundus' appearance is classically associated with which condition?

Behçet's disease
Sarcoidosis
Vogt-Koyanagi-Harada syndrome (Correct answer)
Toxoplasmosis

Correct answer: Vogt-Koyanagi-Harada syndrome

VKH syndrome causes bilateral granulomatous panuveitis with depigmentation of the choroid, producing the characteristic orange-red 'sunset glow' fundus appearance.

Question 107: Which test specifically measures stereoacuity and is commonly used in vision therapy assessment?

Cover-uncover test
Hirschberg corneal reflex test
Maddox rod test
Randot stereotest (Correct answer)

Correct answer: Randot stereotest

The Randot stereotest uses polarized vectographic targets to measure global and local stereopsis in arc seconds, quantifying binocular depth perception.

Question 108: Which preservative in multi-dose eye drops is most commonly associated with corneal toxicity with chronic use?

Benzalkonium chloride (BAK) (Correct answer)
PHMB (polyhexamethylene biguanide)
Sodium chlorite (Purite)
Polyquaternium-1 (Polyquad)

Correct answer: Benzalkonium chloride (BAK)

BAK is the most commonly used preservative but is a detergent that disrupts corneal epithelial tight junctions and promotes apoptosis with chronic exposure, especially in glaucoma patients.

Question 109: Which of the following tests is commonly used to assess a child's visual acuity?

Visual field test
Retinoscopy
Snellen chart (Correct answer)
Tonometry

Correct answer: Snellen chart

The Snellen chart is a common tool used to measure visual acuity, where the child reads letters or symbols from a distance.

Question 110: What condition is characterized by an imbalance in the eye muscles, leading to misalignment of the eyes?

Astigmatism
Strabismus (Correct answer)
Amblyopia
Hyperopia

Correct answer: Strabismus

Strabismus is a condition where the eyes do not properly align with each other, often referred to as ""crossed eyes.""

Question 111: Topical corticosteroids used for ocular inflammation can cause which serious ocular complication with prolonged use?

Retinal detachment and macular hole
Optic nerve drusen and pseudopapilledema
Posterior subcapsular cataracts and elevated IOP (steroid-induced glaucoma) (Correct answer)
Corneal neovascularization and thinning

Correct answer: Posterior subcapsular cataracts and elevated IOP (steroid-induced glaucoma)

Long-term topical steroid use induces posterior subcapsular cataracts and increases IOP in susceptible 'steroid responders' by reducing trabecular outflow facility.

Question 112: A telescope is used as a low vision device to improve:

Near reading acuity at short distances
Peripheral visual field expansion
Contrast sensitivity primarily
Distance visual acuity (Correct answer)

Correct answer: Distance visual acuity

Telescopes magnify distant objects and are prescribed to improve distance VA for activities like TV viewing, classroom use, and navigation in low vision patients.

Question 113: Anisometropia is defined as a difference in refractive error between the two eyes greater than:

1.00 D (Correct answer)
0.50 D
0.25 D
2.50 D

Correct answer: 1.00 D

A clinically significant difference of ≥1.00 D in spherical equivalent between the two eyes is the commonly used threshold for anisometropia.

Question 114: Which systemic disease is most associated with optic neuritis leading to a central scotoma in young adults?

Hypertension
Multiple sclerosis (Correct answer)
Type 2 diabetes
Hypothyroidism

Correct answer: Multiple sclerosis

Optic neuritis in young adults carries a significant risk of multiple sclerosis, and demyelination is the most common systemic cause.

Question 115: What is the hallmark sign of a posterior vitreous detachment (PVD)?

Roth spots
Weiss ring (Correct answer)
Cherry red spot
Shafer's sign

Correct answer: Weiss ring

A Weiss ring is the annular floater seen upon PVD, representing the detached peripapillary glial tissue ring formerly attached at the disc margin.

Question 116: Which anti-VEGF agent is FDA-approved for neovascular (wet) AMD treatment by intravitreal injection?

Bevacizumab (Avastin) off-label only
Triamcinolone acetonide
Ranibizumab (Lucentis)
Aflibercept (Eylea) and ranibizumab both approved (Correct answer)

Correct answer: Aflibercept (Eylea) and ranibizumab both approved

Both aflibercept (Eylea) and ranibizumab (Lucentis) are FDA-approved for neovascular AMD; bevacizumab is widely used off-label due to cost differences.

Question 117: Topical beta-blockers such as timolol lower IOP by:

Increasing uveoscleral outflow
Constricting pupil diameter to widen the drainage angle
Decreasing aqueous humor production by the ciliary body (Correct answer)
Decreasing episcleral venous pressure

Correct answer: Decreasing aqueous humor production by the ciliary body

Beta-blockers block beta-2 adrenoceptors on the ciliary epithelium, reducing cyclic AMP and thereby decreasing aqueous humor secretion by 20–35%.

Question 118: Prentice's rule states that prism at a point in a lens equals:

Lens power (D) ÷ Decentration (mm)
Pupillary distance × Lens power
Decentration (cm) × Lens power (D) (Correct answer)
Lens power (D) × Patient age

Correct answer: Decentration (cm) × Lens power (D)

Prentice's rule: P (prism diopters) = c (cm of decentration) × F (lens power in diopters), used to calculate induced prism from decentered lenses.

Question 119: Snellen acuity of 20/40 means the patient can resolve at 20 feet what a normal eye resolves at:

80 feet
10 feet
20 feet
40 feet (Correct answer)

Correct answer: 40 feet

Snellen notation is a ratio: the numerator is the testing distance (20 ft) and the denominator is the distance at which the letter subtends 5 arc minutes for a normal observer.

Question 120: Rose bengal vital dye is used in optometric examination to stain:

Devitalized and dead corneal/conjunctival epithelial cells (Correct answer)
Healthy epithelial cells only
Basement membrane defects in the corneal stroma
Fluorescent areas of aqueous leakage (Seidel test)

Correct answer: Devitalized and dead corneal/conjunctival epithelial cells

Rose bengal stains devitalized, dead, or mucus-covered cells that lack adequate mucin coating, making it useful for diagnosing keratoconjunctivitis sicca and herpetic disease.

Question 121: The base curve of a contact lens is selected primarily based on:

Palpebral aperture width
Corneal curvature (keratometry readings) (Correct answer)
Pupil diameter in dim illumination
Corneal diameter only

Correct answer: Corneal curvature (keratometry readings)

Keratometry (or corneal topography) measures the anterior corneal curvature, which is used to select an appropriate base curve for proper lens-to-cornea fitting relationship.

Question 122: Which type of insurance is most commonly used to cover routine eye exams and corrective lenses?

Life insurance
Disability insurance
Health insurance
Vision insurance (Correct answer)

Correct answer: Vision insurance

Vision insurance specifically covers routine eye care services such as exams, glasses, and contact lenses.

Question 123: Which of the following is NOT a symptom of vision problems in children?

Excellent academic performance (Correct answer)
Frequent headaches
Squinting
Sitting too close to the TV

Correct answer: Excellent academic performance

Excellent academic performance is generally not a symptom of vision problems, whereas squinting, headaches, and sitting close to the TV can indicate issues.

Question 124: What is the primary mechanism of damage in glaucoma?

Retinal ganglion cell apoptosis (Correct answer)
Choroidal ischemia
Photoreceptor degeneration
Corneal endothelial decompensation

Correct answer: Retinal ganglion cell apoptosis

Glaucoma fundamentally involves progressive apoptosis of retinal ganglion cells and their axons forming the optic nerve, leading to visual field loss.

Question 125: When prescribing reading glasses for a presbyopic patient in their 70s, the optometrist should expect the full near add to be approximately:

+4.00 D for computer distance only
+1.50 D regardless of working distance
+2.50 to +3.00 D for a 40 cm working distance (Correct answer)
+1.00 D for any working distance

Correct answer: +2.50 to +3.00 D for a 40 cm working distance

By the mid-60s most patients have lost all functional accommodation; a +2.50 D add is needed for the standard 40 cm reading distance, potentially adjusted for the patient's preferred working distance.

Question 126: Which eye condition is characterized by an uneven curvature of the cornea?

Astigmatism (Correct answer)
Myopia
Presbyopia
Hyperopia

Correct answer: Astigmatism

Astigmatism occurs when the cornea has an irregular shape, causing blurred or distorted vision.

Question 127: Vergence therapy typically uses which primary instrument to improve fusional vergence ranges?

Worth 4-dot test
Corneal topographer
Prism bar or Brock string (Correct answer)
Trial lens set

Correct answer: Prism bar or Brock string

Prism bars and the Brock string are foundational tools for training vergence demand and improving the amplitude and facility of fusional vergence responses.

Question 128: Which optical low vision device provides the highest magnification but requires the shortest working distance?

Telemicroscope
Handheld magnifier
Bar magnifier
High-plus microscopic spectacles (Correct answer)

Correct answer: High-plus microscopic spectacles

High-plus microscopic spectacle lenses (e.g., +20D) provide high magnification but require very short working distances (5 cm for +20D), limiting their practical use.

Question 129: The cup-to-disc ratio (CDR) that is most suspicious for glaucomatous damage is:

0.8 with asymmetry between eyes (Correct answer)
0.4 with small disc
0.3 symmetric bilaterally
0.5 symmetric bilaterally

Correct answer: 0.8 with asymmetry between eyes

A CDR of 0.8 or greater, especially with inter-eye asymmetry exceeding 0.2, is highly suspicious for glaucomatous optic nerve damage.

Question 130: Topical antihistamine-mast cell stabilizer combinations (e.g., olopatadine) are first-line treatment for:

Viral keratoconjunctivitis
Fungal keratitis
Allergic conjunctivitis (Correct answer)
Bacterial conjunctivitis

Correct answer: Allergic conjunctivitis

Dual-acting antihistamine/mast cell stabilizers like olopatadine block H1 receptors and prevent mast cell degranulation, providing rapid and sustained relief from allergic conjunctivitis symptoms.

Question 131: Which of the following is a risk factor for developing myopia in children?

Regular physical exercise
Reading or doing close work for extended periods (Correct answer)
A balanced diet
Spending time outdoors

Correct answer: Reading or doing close work for extended periods

Prolonged near work, such as reading, has been associated with an increased risk of developing myopia in children.

Question 132: Which condition is characterized by painless, progressive peripheral vision loss and elevated intraocular pressure?

Diabetic retinopathy
Primary open-angle glaucoma (Correct answer)
Acute angle-closure glaucoma
Age-related macular degeneration

Correct answer: Primary open-angle glaucoma

Primary open-angle glaucoma (POAG) typically presents with painless, insidious peripheral visual field loss often accompanied by elevated IOP.

Question 133: The minimum recommended wearing schedule for a new soft contact lens wearer during the adaptation period is:

4 hours per day with no increase for the first month
Full-time wear from day one to accelerate adaptation
Gradually increasing from 4–6 hours to full-time over 1–2 weeks (Correct answer)
Alternating daily lens and spectacle wear for 3 months

Correct answer: Gradually increasing from 4–6 hours to full-time over 1–2 weeks

New wearers should adapt gradually, starting at 4–6 hours and increasing by 1–2 hours per day to allow corneal physiology and eyelid tolerance to adjust.

Question 134: Which photoreceptor type is responsible for scotopic (low-light) vision and is most densely concentrated in the peripheral retina?

Intrinsically photosensitive retinal ganglion cells
M-cones
S-cones
Rods (Correct answer)

Correct answer: Rods

Rods are highly sensitive photoreceptors that mediate scotopic vision and are densely distributed in the peripheral retina, outside the fovea.

Question 135: Atropine 1% eye drops cause cycloplegia and mydriasis by:

Activating nicotinic receptors in the extraocular muscles
Blocking muscarinic receptors in the iris sphincter and ciliary body (Correct answer)
Blocking beta receptors in the ciliary epithelium
Stimulating alpha-1 adrenergic receptors in the iris dilator

Correct answer: Blocking muscarinic receptors in the iris sphincter and ciliary body

Atropine competitively blocks muscarinic (M3) receptors, preventing acetylcholine from stimulating the iris sphincter (causing mydriasis) and ciliary muscle (causing cycloplegia).

Question 136: The AC/A ratio describes the relationship between:

Axial length and corneal curvature
Amplitude of accommodation and age
Anterior chamber depth and intraocular pressure
Accommodative convergence and accommodation (Correct answer)

Correct answer: Accommodative convergence and accommodation

The AC/A ratio quantifies how many prism diopters of convergence (AC) are elicited per diopter of accommodation (A) stimulated.

Question 137: Hydroxychloroquine (Plaquenil) toxicity screening requires which specific test?

Applanation tonometry and gonioscopy
Fluorescein angiography of the optic disc
10-2 visual field testing and spectral-domain OCT of the macula (Correct answer)
Corneal topography and keratometry

Correct answer: 10-2 visual field testing and spectral-domain OCT of the macula

Hydroxychloroquine causes a characteristic bull's-eye maculopathy detectable early by 10-2 fields and SD-OCT parafoveal thinning, per AAO screening guidelines.

NBEO Part I Applied Basic Science (ABS) — Optometry Board Exam

The NBEO Part I Applied Basic Science (ABS) exam assesses the foundational science knowledge required to enter clinical optometry, covering optics, anatomy, pharmacology, microbiology/pathology, and biochemistry. It is a required licensing examination administered by the National Board of Examiners in Optometry for U.S. optometry licensure.

370

Questions

480 min

Time Limit

75%

To Pass

Checking for saved progress...

Exam Rules

You can skip questions and return to them later
Flag questions for review before submitting
No feedback shown until you submit the entire exam
Unanswered questions count as wrong — answer everything
10 pretest questions are mixed in and don't affect your score
Timer auto-submits when time runs out
Your progress is auto-saved every 30 seconds

These practice questions were written with AI tools. They are not real exam questions. Exam facts are checked against the official sources listed below. Not reviewed by a subject-matter expert. Editorial policy

Sources & references

Exam facts on this page (fees, format, dates, passing scores) are checked against these official sources; the date is our last check. Editorial policy

aoa.org — Test delivery, test dates, eligibility, fees, exam format, passing score, retake fee, retake policy, score release, time limit · verified Oct 2026
prometric.com — Test delivery · verified Oct 2026