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

Question 1: Which optical low vision device provides the highest magnification but requires the shortest working distance?

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

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 2: Atropine 1% eye drops cause cycloplegia and mydriasis by:

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

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 3: Prism adaptation test before strabismus surgery is used to:

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

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 4: Intraocular pressure (IOP) is primarily regulated by the balance between aqueous humor production and outflow through which primary drainage pathway?

Uveoscleral pathway
Vortex veins
Suprachoroidal space
Trabecular meshwork and Schlemm's canal (Correct answer)

Correct answer: Trabecular meshwork and Schlemm's canal

Approximately 80–90% of aqueous outflow occurs through the trabecular meshwork into Schlemm's canal, making this the conventional pathway primarily responsible for IOP regulation.

Question 5: Systemic side effects of topical phenylephrine 10% include:

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

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 6: Scleral contact lenses differ from corneal RGP lenses primarily because they:

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

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 7: Pseudoexfoliation syndrome is associated with which significant systemic risk?

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

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

Glaucoma
Cataract (Correct answer)
Onchocerciasis
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 9: Amblyopia is defined as reduced best-corrected visual acuity in one or both eyes due to:

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

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

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

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

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

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

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

Correct answer: Vision insurance

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

Question 13: Accommodative esotropia is most effectively treated initially with:

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

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 14: The Maddox rod test is used primarily to assess:

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

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

20/400 or worse in both eyes
Less than 20/100 in the worse eye
20/200 or worse in the better eye, or visual field ≤20° (Correct answer)
20/200 in one eye regardless of the fellow 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 16: Anisometropia is defined as a difference in refractive error between the two eyes greater than:

0.25 D
0.50 D
1.00 D (Correct answer)
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 17: Which preservative in multi-dose eye drops is most commonly associated with corneal toxicity with chronic use?

Sodium chlorite (Purite)
PHMB (polyhexamethylene biguanide)
Benzalkonium chloride (BAK) (Correct answer)
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 18: Brimonidine (alpha-2 agonist) lowers IOP through which dual mechanism?

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

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 19: The ciliary muscle contraction during accommodation causes which change to the crystalline lens?

The lens moves anteriorly without changing shape
The lens diameter increases
The lens becomes more convex as zonular tension decreases (Correct answer)
The lens flattens due to increased zonular tension

Correct answer: The lens becomes more convex as zonular tension decreases

When the ciliary muscle contracts, it moves anteriorly and inward, releasing zonular tension and allowing the elastic lens to assume a more spherical (convex) shape, increasing its power for near focus.

Question 20: 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
Presence of astigmatism above 1.50D
Myopia greater than 6 diopters

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

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

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

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

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

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

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

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

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

Background retinopathy
Preproliferative retinopathy
Non-proliferative diabetic 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 26: Age-related changes to the accommodative system include all of the following EXCEPT:

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

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

Interpalpebral fit
Steep (vaulting) fit (Correct answer)
Flat 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 28: Which of the following tests is commonly used to assess a child's visual acuity?

Tonometry
Retinoscopy
Visual field test
Snellen chart (Correct answer)

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

A wedge-shaped area of retinal whitening (Correct answer)
Pigment clumping in the periphery
Disc neovascularization
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 30: Which ocular finding is pathognomonic for ocular hypertension secondary to pseudoexfoliation syndrome?

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

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

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

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

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

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

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

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 34: Fluorescein dye in optometric practice is used primarily for:

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

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 35: 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 36: Prostaglandin analogs (e.g., latanoprost) lower intraocular pressure by:

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

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

Astigmatism (Correct answer)
Hyperopia
Presbyopia
Myopia

Correct answer: Astigmatism

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

Question 38: Which photoreceptor type is responsible for scotopic (low-light) vision and is most densely concentrated in the peripheral retina?

Intrinsically photosensitive retinal ganglion cells
S-cones
M-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 39: Which contact lens material parameter describes the amount of oxygen that actually reaches the cornea?

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

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

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

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 41: 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
Pigment dispersion into the trabecular meshwork
Anterior chamber angle closure

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

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

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

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

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

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

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

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

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

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

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 47: 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
Behind the examiner (hyperopia or low myopia) (Correct answer)
In front of the examiner (high myopia)

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

Amacrine cells
Rods
Horizontal cells
Cone photoreceptors (Correct answer)

Correct answer: Cone photoreceptors

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

Question 49: What is the primary purpose of the 'fitting cross' used in multifocal soft contact lens evaluation?

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

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 50: The retinal pigment epithelium (RPE) performs all of the following functions EXCEPT:

Maintenance of the outer blood-retinal barrier
Production of aqueous humor (Correct answer)
Phagocytosis of shed photoreceptor outer segments
Vitamin A metabolism and transport

Correct answer: Production of aqueous humor

Aqueous humor is produced by the ciliary body epithelium, not the RPE; the RPE's roles include photoreceptor outer segment phagocytosis, vitamin A cycling, and forming the outer blood-retinal barrier.

Question 51: Chromatic aberration in the eye is primarily responsible for which clinical phenomenon?

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

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 52: What is the main treatment for amblyopia in children?

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

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 53: Silicone hydrogel lenses have largely replaced conventional hydrogel lenses because they offer:

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

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

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

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 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
Expand the peripheral visual field artificially
Increase fixation stability in the fovea

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: What is the primary mechanism of damage in glaucoma?

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

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 57: The principal effect of a minus cylinder lens is to:

Increase power equally in all meridians
Rotate the axis of astigmatism by 90°
Reduce power in one meridian while leaving the other unchanged (Correct answer)
Reduce 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 58: What condition is characterized by an imbalance in the eye muscles, leading to misalignment of the eyes?

Hyperopia
Astigmatism
Strabismus (Correct answer)
Amblyopia

Correct answer: Strabismus

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

Question 59: Electronic magnification devices (CCTV or video magnifiers) offer which advantage over optical magnifiers?

No power source required for portability
Better for patients with central field loss than peripheral loss
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 60: Which layer of the tear film, produced by the meibomian glands, serves as the outermost layer and prevents evaporation?

Aqueous layer
Glycocalyx layer
Lipid layer (Correct answer)
Mucin layer

Correct answer: Lipid layer

The outermost lipid layer, secreted by the meibomian glands, reduces evaporation of the underlying aqueous layer and stabilizes the tear film.

Question 61: Which layer of the cornea is responsible for its transparency and makes up approximately 90% of corneal thickness?

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

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

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

Correct answer: Ciliary body epithelium

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

Question 63: Which of the following is a common refractive error in children?

Macular degeneration
Glaucoma
Myopia (Correct answer)
Cataracts

Correct answer: Myopia

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

Question 64: What is the purpose of vision therapy in pediatric optometry?

To improve visual skills and processing (Correct answer)
To correct refractive errors
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 65: When prescribing reading glasses for a presbyopic patient in their 70s, the optometrist should expect the full near add to be approximately:

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

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

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

Correct answer: Property insurance

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

Question 67: Which systemic disease is most associated with optic neuritis leading to a central scotoma in young adults?

Type 2 diabetes
Multiple sclerosis (Correct answer)
Hypertension
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 68: Convergence insufficiency is best defined as:

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
Intermittent exotropia greater at distance

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

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

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

To provide health benefits to employees
To insure the building against natural disasters
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 71: The optic nerve is surrounded by an extension of which meningeal layer that forms the optic nerve sheath?

Dura mater only
All three meningeal layers (Correct answer)
Arachnoid mater only
Pia 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 72: 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 73: What is the hallmark sign of a posterior vitreous detachment (PVD)?

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

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

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

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

Professional liability insurance
Employment practices liability insurance (Correct answer)
Vision insurance
Health 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 76: Topical antihistamine-mast cell stabilizer combinations (e.g., olopatadine) are first-line treatment for:

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

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

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

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

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

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 79: Topical beta-blockers such as timolol lower IOP by:

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

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 80: Which of the following best describes the blood supply to the outer retina (photoreceptors and RPE)?

Central retinal artery capillaries
Choriocapillaris of the choroid (Correct answer)
Posterior ciliary artery branches within the retina
Anterior ciliary arteries

Correct answer: Choriocapillaris of the choroid

The outer retina, including photoreceptors and the RPE, receives its oxygen and nutrients by diffusion from the choriocapillaris of the choroid, as the retinal capillaries do not extend into the outer retinal layers.

Question 81: Which treatment is considered the gold standard for anisometropic amblyopia?

Vision therapy alone without refractive correction
Immediate patching before refractive correction
Surgical realignment of the eyes
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 82: Horner's syndrome results from a lesion of which neural pathway?

Sympathetic pathway to the iris sphincter
Parasympathetic pathway to the iris dilator
Sympathetic pathway to the iris dilator and Müller's muscle (Correct answer)
Parasympathetic pathway to the iris sphincter

Correct answer: Sympathetic pathway to the iris dilator and Müller's muscle

Horner's syndrome is caused by interruption of the sympathetic pathway, leading to ptosis (Müller's muscle), miosis (iris dilator), and anhidrosis on the ipsilateral side.

Question 83: The mechanism of action of carbonic anhydrase inhibitors (e.g., dorzolamide) in glaucoma treatment is:

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

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

Bilateral superior oblique palsy
Paresis of a left-gaze muscle in one eye (Correct answer)
Primary position exophoria
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 85: The central retinal artery is a branch of which vessel?

Internal carotid artery
Posterior ciliary artery
Ophthalmic artery (Correct answer)
Anterior ciliary 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 86: The pupillary light reflex (direct and consensual) relies on which afferent pathway?

Optic nerve → lateral geniculate nucleus → visual cortex → Edinger-Westphal nucleus
Optic nerve → pretectal nucleus → bilateral Edinger-Westphal nuclei (Correct answer)
Optic nerve → lateral geniculate nucleus → ciliary ganglion
Optic nerve → superior colliculus → ciliary ganglion

Correct answer: Optic nerve → pretectal nucleus → bilateral Edinger-Westphal nuclei

The afferent limb of the pupillary light reflex travels via the optic nerve to the pretectal nucleus in the midbrain, which projects bilaterally to the Edinger-Westphal nuclei, enabling both direct and consensual responses.

Question 87: The power of a thin lens required to correct a 4D myope is:

+2.00 D
-4.00 D (Correct answer)
+4.00 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 88: Orthokeratology (ortho-K) lenses work primarily by:

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

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

It provides health benefits to employees
It increases the coverage limits beyond the primary policy (Correct answer)
It replaces the need for professional liability insurance
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 90: Low vision rehabilitation is indicated when a patient's best-corrected visual acuity is:

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

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 91: Contrast sensitivity testing is important in geriatric optometry because:

It determines the need for anti-reflective coatings only
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

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

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

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

Prism bar or Brock string (Correct answer)
Corneal topographer
Worth 4-dot test
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 94: What is the FDA oxygen transmissibility threshold for extended-wear soft contact lenses?

Dk/t ≥ 125 ISO units
Dk/t ≥ 87 ISO units (Correct answer)
Dk/t ≥ 24 ISO units
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 95: Drusen deposits beneath the retinal pigment epithelium are most associated with which disease process?

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

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

Color vision deficiency
Intraocular pressure changes
Peripheral visual field constriction
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 97: A patient presents with sudden onset of a dark curtain moving across their vision. Which condition is most likely?

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

Correct answer: Retinal detachment

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

Question 98: What is the primary role of a third-party administrator in relation to vision insurance plans?

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

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

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

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

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

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

Retinoblastoma
Uveal melanoma (Correct answer)
Choroidal hemangioma
Metastatic carcinoma

Correct answer: Uveal melanoma

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

Question 102: The corneal endothelium maintains corneal deturgescence primarily through which mechanism?

Active ion pumping via Na+/K+-ATPase to move fluid from the stroma to the anterior chamber (Correct answer)
Secretion of mucin to repel water
Contraction of tight junctions to prevent any fluid entry
Passive diffusion driven by oncotic pressure

Correct answer: Active ion pumping via Na+/K+-ATPase to move fluid from the stroma to the anterior chamber

Corneal endothelial cells use Na+/K+-ATPase pumps to actively transport fluid from the corneal stroma into the aqueous humor, counteracting the natural tendency of the stroma to imbibe water and maintaining corneal clarity.

Question 103: In low vision rehabilitation, a stand magnifier is preferred over a hand magnifier when a patient has:

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
Good distance acuity but reduced near acuity only

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

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

Question 105: The far point of a +3.00 D corrected hyperope (corrected at far) is located:

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

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

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

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 107: Strabismus surgery for constant exotropia primarily aims to:

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

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

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

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

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

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

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

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

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

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

To ensure payment for services rendered (Correct answer)
To establish a diagnosis
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 113: Snellen acuity of 20/40 means the patient can resolve at 20 feet what a normal eye resolves at:

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

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

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

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

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

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

Near reading acuity at short distances
Contrast sensitivity primarily
Peripheral visual field expansion
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 117: 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)
Preservative-free unit-dose saline
Hydrogen peroxide systems
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 118: Which lens aberration causes peripheral blur and is addressed by aspheric lens designs?

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

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

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

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

Ring scotoma with peripheral constriction (Correct answer)
Altitudinal defect
Central scotoma
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 121: Which structure forms the blood-aqueous barrier on the anterior surface of the iris?

Iris stroma endothelium
Iris pigment epithelium
Non-pigmented ciliary epithelium
Iris vascular endothelium with tight junctions (Correct answer)

Correct answer: Iris vascular endothelium with tight junctions

The anterior blood-aqueous barrier is formed by tight junctions between the endothelial cells of iris blood vessels, preventing large molecules from leaking into the aqueous humor.

Question 122: The minimum add power for a presbyopic patient is determined by:

The patient's age divided by 10
The patient's distance refractive error alone
The near point of convergence distance
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 123: Which layer of the cornea is replaced by pump activity and is responsible for maintaining corneal deturgesence?

Endothelium (Correct answer)
Stroma
Bowman's layer
Epithelium

Correct answer: Endothelium

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

Question 124: When performing the duochrome (bichrome) test, if both red and green appear equally clear, the endpoint indicates:

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

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

Hirschberg corneal reflex test
Maddox rod test
Cover-uncover 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 126: The AC/A ratio describes the relationship between:

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

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

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

Correct answer: Surgical procedures

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

Question 128: 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 129: Contact lens-induced corneal neovascularization is primarily caused by:

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

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

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

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 131: Polypharmacy in elderly patients is relevant to optometry because:

Many systemic medications cause ocular side effects including dry eye, angle changes, and lens toxicity (Correct answer)
Polypharmacy has no relationship to ocular conditions
Most systemic drugs improve intraocular pressure control
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 132: 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 133: Which of the following is typically included in an optometrist's business owner's policy (BOP)?

Workers' compensation insurance
Vision insurance
Property insurance and general liability insurance (Correct answer)
Health 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 134: The cup-to-disc ratio (CDR) that is most suspicious for glaucomatous damage is:

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

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 135: Which clinical finding is most characteristic of keratoconus?

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

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

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

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

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

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

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

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

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

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 140: The vitreous humor is composed primarily of which substance?

Albumin and globulins
Hyaluronic acid and collagen fibrils (Correct answer)
Phospholipids and glycoproteins
Fibronectin and laminin

Correct answer: Hyaluronic acid and collagen fibrils

The vitreous is approximately 99% water, with the structural framework provided by a network of hyaluronic acid (providing viscosity) and collagen fibrils (type II and IX).

Question 141: 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 142: When transposing a spectacle prescription from plus cylinder to minus cylinder form, which step is performed LAST?

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

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 143: The physiologic blind spot corresponds to which retinal structure?

Ora serrata
Fovea centralis
Macula lutea
Optic nerve head (optic disc) (Correct answer)

Correct answer: Optic nerve head (optic disc)

The optic disc is devoid of photoreceptors where retinal ganglion cell axons exit the eye as the optic nerve, creating an absolute scotoma known as the physiologic blind spot.

Question 144: Which layer of the retina contains the cell bodies of the photoreceptors?

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

Correct answer: Outer nuclear layer

The outer nuclear layer contains the cell bodies (nuclei) of the rod and cone photoreceptors.

Question 145: Oral acetazolamide (Diamox) used for acute IOP reduction works by inhibiting which enzyme?

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

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

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

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 147: Which cranial nerve innervates the lateral rectus muscle?

CN IV (Trochlear)
CN III (Oculomotor)
CN V (Trigeminal)
CN VI (Abducens) (Correct answer)

Correct answer: CN VI (Abducens)

The abducens nerve (CN VI) exclusively innervates the lateral rectus muscle, which abducts the eye.

Question 148: What type of insurance coverage is crucial for protecting an optometric practice against data breaches and cyber-attacks?

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

Correct answer: Cyber liability insurance

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

Question 149: The most common cause of irreversible vision loss in Americans over age 65 is:

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

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 150: The macula lutea gets its yellow color from which pigments?

Carotenoids and hemoglobin
Lutein and zeaxanthin (Correct answer)
Melanin and rhodopsin
Lipofuscin and flavoproteins

Correct answer: Lutein and zeaxanthin

The macular pigment is composed of lutein and zeaxanthin, two xanthophyll carotenoids that absorb blue light and are thought to protect the macula from phototoxic damage.

Question 151: With-the-rule astigmatism is defined as when:

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

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.

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

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