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

Question 1: Brimonidine (alpha-2 agonist) lowers IOP through which dual mechanism?

Blocking muscarinic receptors in ciliary body
Increasing trabecular outflow only
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 2: Age-related changes to the accommodative system include all of the following EXCEPT:

Hardening of the crystalline lens nucleus
Reduced ciliary muscle contractility
Reduction in corneal refractive power (Correct answer)
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 3: Rubeosis iridis (neovascularization of the iris) is a complication most associated with which condition?

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

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 4: Orthokeratology (ortho-K) lenses work primarily by:

Surgically flattening the stroma
Reducing aqueous production
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 5: Which choroidal tumor appears as an orange-red elevated lesion on fundoscopy and is the most common primary intraocular malignancy in adults?

Retinoblastoma
Choroidal hemangioma
Uveal melanoma (Correct answer)
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 6: Why is it important for optometrists to verify a patient's insurance benefits before providing services?

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

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

Horizontal cells
Amacrine 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 8: Topical beta-blockers such as timolol lower IOP by:

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

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 9: Accommodative esotropia is most effectively treated initially with:

Patching of the non-dominant eye
Surgical recession of the medial rectus
Full cycloplegic refraction and spectacle correction (Correct answer)
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 10: Giant papillary conjunctivitis (GPC) in contact lens wearers is best managed by:

Increasing lens replacement frequency to monthly
Switching to daily disposable lenses and reducing wear time (Correct answer)
Prescribing topical antibiotic drops
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 11: Intraocular pressure (IOP) is primarily regulated by the balance between aqueous humor production and outflow through which primary drainage pathway?

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

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

40 feet (Correct answer)
10 feet
80 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 13: Which type of insurance is most commonly used to cover routine eye exams and corrective lenses?

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

Correct answer: Vision insurance

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

Question 14: 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 15: Which type of diabetic retinopathy is characterized by the presence of new blood vessel formation?

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

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

Ranibizumab (Lucentis)
Bevacizumab (Avastin) off-label only
Aflibercept (Eylea) and ranibizumab both approved (Correct answer)
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 17: 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 18: Which preservative in multi-dose eye drops is most commonly associated with corneal toxicity with chronic use?

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

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 19: What is the primary mechanism of damage in glaucoma?

Choroidal ischemia
Photoreceptor degeneration
Corneal endothelial decompensation
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 20: Which insurance is required by law for most employers to provide to their employees, covering work-related injuries and illnesses?

Health insurance
Professional liability insurance
Vision 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 21: Which extraocular muscle is responsible for intorsion of the eye when it is in the primary position?

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

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

Employment practices liability insurance (Correct answer)
Health insurance
Vision insurance
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 23: Which treatment is considered the gold standard for anisometropic amblyopia?

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

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

It screens for color blindness in elderly patients
It detects functional vision loss not captured by Snellen acuity (Correct answer)
It measures the amplitude of accommodation accurately
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 25: What is the hallmark sign of a posterior vitreous detachment (PVD)?

Cherry red spot
Roth spots
Shafer's sign
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 26: 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 27: The critical period for amblyopia treatment is generally considered to close around:

18 years of age
2–3 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 28: The cup-to-disc ratio (CDR) that is most suspicious for glaucomatous damage is:

0.8 with asymmetry between eyes (Correct answer)
0.5 symmetric bilaterally
0.3 symmetric bilaterally
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 29: Which layer of the cornea is responsible for its transparency and makes up approximately 90% of corneal thickness?

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

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.

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.

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35 min

Time Limit

75%

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