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NBEO Part III study materials
NBEO Part III study resources

NBEO Part III practice questions

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Question 1Patient History and Interviewing

A 68-year-old patient reports a sudden onset of painless, transient graying of vision in the right eye lasting about 5 minutes, occurring twice today. Which element of the history most directly raises concern for an embolic carotid source?

  1. The patient is over age 60
  2. The visual loss was transient and painless Correct answer.
  3. The episodes lasted several minutes each
  4. The symptoms occurred repeatedly within one day

Explanation

Amaurosis fugax is classically described as transient, painless, monocular loss of vision, often a curtain or shade, and this pattern suggests transient ischemia from an embolic source such as the internal carotid artery. Duration and repetition add urgency but do not by themselves localize the mechanism. Age is a risk factor rather than the defining historical feature.

Question 2Patient History and Interviewing

During the case history, a patient describes a gradual, painless loss of peripheral vision over months with difficulty seeing at night. Which follow-up question is most useful for clarifying this symptom pattern?

  1. Do straight lines appear bent or distorted to you?
  2. Does the vision loss affect one eye only or both eyes? Correct answer.
  3. Do you notice halos or glare around lights in the evening?
  4. Have you had any eye pain or redness with these episodes?

Explanation

Gradual painless peripheral field loss with nyctalopia suggests a bilateral process such as glaucoma or a retinal dystrophy, so establishing whether one or both eyes are involved helps localize and characterize the complaint. Halos and glare relate to cataract or angle closure, pain and redness suggest inflammation, and metamorphopsia points to macular disease, none of which matches this presentation.

Question 3Patient History and Interviewing

A patient reports intermittent episodes in which one eye becomes red, painful, and blurred, each lasting a few hours and resolving spontaneously. Which historical feature is most important to elicit next?

  1. Whether the episodes are associated with headache and nausea
  2. Whether the patient wears contact lenses
  3. Whether the episodes occur in dim light or after reading Correct answer.
  4. Whether there is a family history of glaucoma

Explanation

Recurrent short episodes of unilateral redness, pain, and blurred vision raise concern for intermittent angle closure, and these episodes are classically provoked by dim illumination or prolonged near work that dilates the pupil. Headache and nausea may accompany acute attacks but are less specific triggers. Contact lens wear and family history are relevant background but do not characterize this stereotypic episodic pattern.

Question 4Patient History and Interviewing

A 45-year-old reports new floaters and flashes in the left eye for two days. Which additional symptom in the history most raises concern for a retinal detachment?

  1. Light sensitivity when reading
  2. Increased tearing in the morning
  3. Mild aching around the eye
  4. A curtain or shadow in the peripheral field Correct answer.

Explanation

A curtain, shade, or shadow extending across the visual field in the setting of new flashes and floaters suggests a retinal tear with detachment and warrants urgent dilated examination. Aching, tearing, and photophobia are more consistent with anterior segment or inflammatory disease and do not localize posterior pathology.

Question 5Patient History and Interviewing

A patient with long-standing diabetes describes a sudden painless loss of vision in one eye that occurred on waking. Which historical detail best helps distinguish a vitreous hemorrhage from an ischemic event?

  1. Whether the patient had eaten breakfast before the event
  2. Whether the patient wears corrective lenses
  3. Whether the patient has hypertension
  4. Whether the loss was accompanied by a shower of new floaters Correct answer.

Explanation

A sudden painless loss accompanied by new floaters or a diffuse reddish haze suggests vitreous hemorrhage from proliferative diabetic retinopathy. Ischemic events such as a central retinal artery occlusion typically produce a profound altitudinal or total loss without new floaters. Meal timing, hypertension history, and refractive correction do not discriminate between these mechanisms.

Question 6Patient History and Interviewing

A patient reports that a central spot of vision is missing in the right eye and that straight lines appear wavy. Which historical element most strongly supports a macular process rather than an optic nerve process?

  1. Pain with eye movement
  2. Color desaturation in the affected eye
  3. A relative afferent pupillary defect
  4. Metamorphopsia with a central scotoma Correct answer.

Explanation

Metamorphopsia combined with a central scotoma localizes disease to the macula, as seen with choroidal neovascularization or macular edema. Pain with eye movement, color desaturation, and an afferent pupillary defect are hallmarks of optic neuropathy such as optic neuritis, which typically spares metamorphopsia.

Question 7Patient History and Interviewing

A patient describes a sudden painless loss of the upper half of vision in one eye that has persisted for several hours. Which question is most relevant to the mechanism of this altitudinal defect?

  1. Do you have a history of high blood pressure or carotid disease? Correct answer.
  2. Have you had a recent upper respiratory infection?
  3. Do you have a family history of cataract?
  4. Have you recently used any new eye drops?

Explanation

An altitudinal field defect reflects ischemia along the retinal or optic nerve vascular supply, often branch retinal artery occlusion or anterior ischemic optic neuropathy, so vascular risk factors such as hypertension and carotid disease are directly relevant. Eye drop use, cataract family history, and recent respiratory infection do not address this vascular mechanism.

Question 8Patient History and Interviewing

A patient being interviewed for a contact lens evaluation reports that her eyes are dry and gritty by the end of the day and that she sometimes wakes with her lids stuck together. Which additional history is most useful for characterizing this complaint?

  1. Family history of retinal detachment
  2. Use of a computer or digital screens for many hours daily Correct answer.
  3. Age at first pair of glasses
  4. History of migraine with visual aura

Explanation

End-of-day dryness and gritty sensation with morning crusting suggest ocular surface disease with an evaporative component, and prolonged screen use reduces blink rate and worsens symptoms. Migraine, retinal detachment family history, and age at first correction are unrelated to this presentation.

Question 9Patient History and Interviewing

During history taking, a patient mentions that his mother lost vision from glaucoma and that he has never had his eyes checked. Which information is most important to obtain to interpret his risk?

  1. The specific type of glaucoma his mother had and her age at diagnosis Correct answer.
  2. Whether his mother wore glasses
  3. The number of siblings he has
  4. Whether his mother had cataract surgery

Explanation

A family history of glaucoma raises risk, but the magnitude depends on the type of glaucoma and the age at which it was diagnosed, since open-angle glaucoma has a strong heritable component while other forms differ. Glasses use, cataract surgery, and sibship size do not refine the risk estimate.

Question 10Patient History and Interviewing

A 30-year-old reports a two-day history of pain on eye movement, decreased color brightness in one eye, and mild blurring. Which historical feature would most support a diagnosis of optic neuritis?

  1. Occasional migraine headaches
  2. Recent viral illness or flu-like symptoms Correct answer.
  3. Long-standing stable myopia
  4. Use of artificial tears

Explanation

Optic neuritis is often preceded by a viral illness and presents with pain on eye movement, color desaturation, and subacute visual loss, frequently in young adults. Stable myopia, migraine, and artificial tear use do not contribute to this inflammatory demyelinating picture.

Question 11Patient History and Interviewing

A patient reports double vision that disappears when either eye is covered. Which question best helps classify this diplopia?

  1. Have you had recent eye trauma?
  2. Do you have a family history of strabismus?
  3. Does the double vision worsen in dim light?
  4. Is the double image side by side, one above the other, or tilted? Correct answer.

Explanation

Binocular diplopia that resolves with occlusion of either eye indicates misalignment, and asking whether the images are horizontal, vertical, or oblique helps localize the affected extraocular muscle or nerve. Worsening in dim light, family history, and trauma are relevant background but do not classify the deviation.

Question 12Patient History and Interviewing

A patient being evaluated for a red eye reports that the redness began after she started using a new brand of mascara and that both lids are itchy and puffy. Which question is most useful for confirming the suspected mechanism?

  1. Have you ever had a chalazion?
  2. Does the itching and swelling improve when you stop using the product? Correct answer.
  3. Have you had a fever or chills?
  4. Do you wear glasses for distance vision?

Explanation

Bilateral itchy, puffy lids after a new cosmetic suggests contact allergic blephatoconjunctivitis, and improvement on withdrawal of the product supports that mechanism. Fever suggests infection, refractive correction is unrelated, and prior chalazion does not confirm an allergic cause.

Question 13Patient History and Interviewing

A patient with a history of angle closure describes an episode of severe eye pain, headache, nausea, and blurred vision with halos that began in the evening. Which historical detail most supports angle closure as the cause?

  1. The pain was relieved by blinking
  2. The blurred vision improved with artificial tears
  3. The episode began after spending time in a darkened movie theater Correct answer.
  4. The episode began after reading in bright light

Explanation

Angle closure is precipitated by pupillary dilation, which occurs in dim illumination, so an episode beginning in a darkened environment supports the diagnosis. Bright light constricts the pupil and is less likely to provoke an attack, and relief with blinking or artificial tears suggests ocular surface disease.

Question 14Patient History and Interviewing

A patient reports a gradual decrease in vision over several years with glare around headlights at night and difficulty reading small print. Which question best helps identify the likely cause?

  1. Does the glare and blurring improve in bright sunlight or with a pinhole? Correct answer.
  2. Have you noticed a shadow or curtain in your side vision?
  3. Do you see flashing lights in the evening?
  4. Is the vision loss worse in one eye only?

Explanation

Gradual bilateral visual decline with glare and difficulty reading suggests cataract, and improvement with brighter light or a pinhole is consistent with an optical cause rather than retinal or neural disease. A shadow or curtain suggests detachment, flashes suggest vitreoretinal traction, and asymmetry alone does not identify the cause.

Question 15Patient History and Interviewing

A patient being interviewed for a comprehensive examination says, 'I sometimes see a dark spot that moves when I look at it, and it has been there for years without change.' Which interpretation of this symptom is most appropriate?

  1. A dark spot that moves is characteristic of a macular hole
  2. A moving spot indicates a vitreous hemorrhage until proven otherwise
  3. A stable dark spot always indicates a retinal detachment requiring urgent referral
  4. A long-standing stable floater is common and does not by itself indicate acute retinal disease Correct answer.

Explanation

A long-standing, stable, mobile floater is a common benign finding in a myopic or aging vitreous and does not by itself suggest acute retinal disease. Sudden new floaters, flashes, or a visual field defect are the features that warrant urgent evaluation. Macular hole causes central distortion and scotoma rather than a mobile spot.

Question 16Patient History and Interviewing

A patient reports a sudden onset of horizontal double vision that is worse when looking to the right and is accompanied by a drooping right eyelid. Which historical feature is most important to ask about next?

  1. History of seasonal allergies
  2. Recent use of reading glasses
  3. Dietary habits
  4. Fluctuating weakness or fatigue worsened by activity Correct answer.

Explanation

Diplopia with ptosis raises concern for a neuromuscular junction disorder or a cranial nerve palsy, and fluctuating weakness worsened by activity suggests myasthenia gravis. Reading glasses, allergies, and diet do not clarify this presentation and would delay appropriate evaluation.

Question 17Visual Acuity and Refraction Procedures

A patient is seated at the standard Snellen distance for a 20/20 line chart calibrated for 6 meters. What testing distance, in feet, corresponds to that calibration?

  1. 20 feet Correct answer.
  2. 10 feet
  3. 6 feet
  4. 16 feet

Explanation

Snellen notation compares the testing distance with the distance at which a letter subtends 5 minutes of arc. The standard 6-meter lane is equivalent to 20 feet, which is why acuity is expressed as 20/20 in feet and 6/6 in meters. Converting meters to feet (6 x 3.28) gives approximately 20 feet.

Question 18Visual Acuity and Refraction Procedures

On a Snellen chart, the 20/40 line is read correctly by a patient at 20 feet. What is the minimum angular size, in minutes of arc, of the critical detail of those letters at that distance?

  1. 2 minutes Correct answer.
  2. 5 minutes
  3. 1 minute
  4. 10 minutes

Explanation

The denominator of the Snellen fraction states the distance at which the letter subtends 5 minutes of arc overall, with the critical detail subtending 1 minute. At 20/40 the patient requires twice the standard angle, so the detail subtends 2 minutes of arc. The overall letter therefore subtends 10 minutes.

Question 19Visual Acuity and Refraction Procedures

A patient counts fingers correctly at 3 feet but cannot identify any letters on the chart at 20 feet. How should this acuity be recorded?

  1. CF at 3 feet Correct answer.
  2. LP at 3 feet
  3. 20/200
  4. HM at 3 feet

Explanation

When a patient cannot read the largest optotype but can count fingers, acuity is recorded as the counting-fingers level at the tested distance. This preserves the graded information rather than converting to a Snellen fraction. Hand motion and light perception represent progressively poorer levels.

Question 20Visual Acuity and Refraction Procedures

A patient reads the 20/30 line at 10 feet instead of the standard 20 feet. Using the distance conversion, what Snellen equivalent should be recorded?

  1. 20/30
  2. 20/15 Correct answer.
  3. 20/40
  4. 20/60

Explanation

When the numerator distance differs from the calibration distance, the recorded acuity is adjusted by the ratio of actual to standard distance. Here the patient achieved at 10 feet what is normally required at 20 feet, so the equivalent is 20/15. The letter size seen at 10 feet corresponds to half the standard angular requirement.

Question 21Visual Acuity and Refraction Procedures

Which chart design feature makes the LogMAR chart preferable to a traditional Snellen chart for detecting small changes in acuity?

  1. Letters arranged in a single column
  2. Equal numbers of letters on each line with proportional spacing Correct answer.
  3. Progressively larger letters toward the bottom
  4. Use of only capital letters

Explanation

LogMAR charts use a constant number of optotypes per line and spacing that scales with letter size, giving each line equal scoring weight and reducing contour interaction. This design produces a linear scale and better test-retest reliability. Traditional Snellen charts vary letter count and spacing between lines.

Question 22Visual Acuity and Refraction Procedures

A LogMAR chart records a patient's acuity as 0.30 logMAR. What Snellen equivalent does this represent?

  1. 20/20
  2. 20/40 Correct answer.
  3. 20/30
  4. 20/60

Explanation

LogMAR is the logarithm of the minimum angle of resolution relative to 1 minute of arc. A logMAR of 0.30 corresponds to an MAR of about 2 minutes, which is 20/40. Each 0.1 logMAR step changes acuity by roughly one Snellen line.

Question 23Visual Acuity and Refraction Procedures

During retinoscopy, the neutral point is reached when the retinoscopic reflex appears to do which of the following?

  1. Break into two separate bands
  2. Fill the pupil completely without apparent movement Correct answer.
  3. Move opposite to the streak
  4. Show a bright crescent at the pupil margin

Explanation

At neutrality the emergent rays from the eye are conjugate with the retinoscope peephole, so the reflex appears to fill the pupil and shows no movement as the streak is swept. This indicates that the working distance lens has neutralized the patient's refractive error. Movement direction before neutrality guides the sign of the correction.

Question 24Visual Acuity and Refraction Procedures

A retinoscopist works at a 67 cm working distance and finds neutrality with a +1.50 D lens in place. What is the patient's net refractive error along that meridian?

  1. +0.50 D Correct answer.
  2. -0.50 D
  3. +2.50 D
  4. +1.50 D

Explanation

The working distance must be subtracted from the neutralizing lens power. A 67 cm working distance corresponds to 1.50 D, so +1.50 D minus 1.50 D leaves +0.50 D of hyperopia. Failing to subtract the working distance would over-plus the prescription.

Question 25Visual Acuity and Refraction Procedures

A 50 cm working distance is used for retinoscopy. What dioptric value must be subtracted from the neutralizing lens to obtain the net refraction?

  1. 0.50 D
  2. 2.00 D Correct answer.
  3. 1.00 D
  4. 3.00 D

Explanation

Working distance in diopters equals the reciprocal of the distance in meters. A 50 cm distance is 0.50 m, and 1/0.50 equals 2.00 D. This amount is subtracted from the neutralizing lens power.

Question 26Visual Acuity and Refraction Procedures

In streak retinoscopy, the streak is oriented vertically and the reflex is seen to move with the streak. Which meridian is being neutralized?

  1. The horizontal meridian Correct answer.
  2. The oblique meridian at 45 degrees
  3. Both principal meridians simultaneously
  4. The vertical meridian

Explanation

The streak orientation indicates the meridian of the reflex being observed, and the movement is evaluated perpendicular to the streak. A vertical streak evaluates the horizontal meridian of the eye. The power found neutralizes that meridian, and the procedure is repeated with the streak rotated 90 degrees.

Question 27Visual Acuity and Refraction Procedures

A patient's retinoscopic reflex shows with-movement in all meridians at a 50 cm working distance. What type of refractive error is most consistent with this finding?

  1. Astigmatism only
  2. High myopia with a neutral reflex
  3. Myopia greater than 2.00 D
  4. Hyperopia or low myopia less than 2.00 D Correct answer.

Explanation

With-movement indicates that the far point lies beyond the retinoscope, consistent with hyperopia or myopia less than the working distance dioptric equivalent. At 50 cm, myopia up to 2.00 D can still show with-movement. Against-movement appears when myopia exceeds the working distance value.

Question 28Visual Acuity and Refraction Procedures

A patient's visual acuity is 20/200 in the right eye and 20/25 in the left eye. What is the approximate logMAR value for the right eye?

  1. 2.00
  2. 0.10
  3. 1.00 Correct answer.
  4. 0.50

Explanation

LogMAR equals the logarithm of the Snellen denominator divided by the numerator, here 200/20 equals 10, and the log of 10 is 1.00. A value of 1.00 logMAR corresponds to 20/200. Each 0.1 unit represents about one line of acuity.

Question 29Visual Acuity and Refraction Procedures

When performing the duochrome (red-green) test, a patient reports that the letters on the red side are clearer. What does this suggest?

  1. The patient is under-minused or relatively hyperopic Correct answer.
  2. The patient has uncorrected astigmatism
  3. The patient's acuity is better than 20/20
  4. The patient is over-minused

Explanation

Longer red wavelengths focus behind shorter green wavelengths, so a red-preferred response indicates the eye is relatively hyperopic for the tested target. This means the correction is under-minused or too plus. Minus is added until the two sides appear equal.

Question 30Visual Acuity and Refraction Procedures

In a duochrome test, a patient prefers the green side. What adjustment is indicated?

  1. Add plus power Correct answer.
  2. No change is needed
  3. Add cylinder power
  4. Add minus power

Explanation

Preference for green indicates the eye is relatively myopic for the test target, meaning the correction is over-minused or under-plussed. Adding plus power shifts focus back toward the red side until balance is reached. The end point is equality of clarity between the two halves.

Question 31Visual Acuity and Refraction Procedures

During Jackson cross-cylinder testing for astigmatism, the patient reports that the two positions appear equally clear. What does this indicate?

  1. The cylinder axis is correct and the power is appropriate Correct answer.
  2. The cylinder power is too high
  3. The cylinder axis is off by 45 degrees
  4. The patient has no astigmatism

Explanation

Equal clarity in both flip positions of the cross-cylinder means the correcting cylinder is properly aligned and powered for that meridian. The endpoint of the cross-cylinder refinement is this equality. Any difference between the two positions indicates residual cylinder error.

Question 32Visual Acuity and Refraction Procedures

A patient's prescription is -2.00 -1.00 x 180. What is the spherical equivalent?

  1. -2.50 D Correct answer.
  2. -1.50 D
  3. -3.00 D
  4. -2.00 D

Explanation

The spherical equivalent equals the sphere plus half the cylinder power. Half of -1.00 D is -0.50 D, which added to -2.00 D gives -2.50 D. This value represents the single spherical lens that places the circle of least confusion on the retina.

Question 33Visual Acuity and Refraction Procedures

A prescription reads +1.00 -2.00 x 090. Which of the following is the equivalent crossed-cylinder form?

  1. -1.00 -2.00 x 180
  2. -1.00 +2.00 x 090
  3. +3.00 -2.00 x 180
  4. -1.00 +2.00 x 180 Correct answer.

Explanation

Converting between plus and minus cylinder form requires summing sphere and cylinder to get the new sphere and rotating the axis by 90 degrees. Summing +1.00 and -2.00 gives -1.00, and the axis 090 becomes 180. The cylinder sign is reversed to +2.00.

Question 34Visual Acuity and Refraction Procedures

A patient's acuity is measured as 20/40 in the right eye. What does the numerator of this Snellen fraction represent?

  1. The patient's far point distance
  2. The distance at which a normal eye can read the letter
  3. The distance at which the patient was tested Correct answer.
  4. The letter size in millimeters

Explanation

In Snellen notation the numerator is the testing distance between the patient and the chart. The denominator is the distance at which a standard observer could identify the same optotype. The fraction therefore compares the patient's performance with a normative reference.

Question 35Visual Acuity and Refraction Procedures

A patient's visual acuity improves from 20/40 to 20/25 when a pinhole is placed over the eye. What does this improvement most likely indicate?

  1. Optic nerve atrophy
  2. An uncorrected refractive error Correct answer.
  3. Macular disease
  4. A media opacity such as a dense cataract

Explanation

A pinhole reduces the size of the blur circle and improves acuity when refractive error is the limiting factor. Improvement with pinhole therefore suggests uncorrected refractive error rather than pathology. Lack of improvement raises suspicion for organic causes of reduced acuity.

Question 36Visual Acuity and Refraction Procedures

When measuring visual acuity in a patient with nystagmus, which modification is most appropriate?

  1. Test with both eyes open and use a larger chart distance Correct answer.
  2. Use a reduced Snellen card at 40 cm
  3. Test one eye at a time with a pinhole only
  4. Test only with the head turned away from the null point

Explanation

Patients with nystagmus often have a null point or gaze position that dampens the oscillation and improves acuity. Binocular testing can also improve acuity relative to monocular testing. Testing conditions should be documented so results are comparable over time.

Question 37Visual Acuity and Refraction Procedures

A patient reads the 20/20 line but makes two errors on the 20/15 line. How should this be recorded using standard Snellen notation?

  1. 20/15
  2. 20/25
  3. 20/40
  4. 20/20 Correct answer.

Explanation

Acuity is recorded as the smallest line on which the patient correctly identifies the majority of optotypes. Errors on a line generally mean that line is not credited. The last fully passed line, 20/20, is therefore recorded.

Question 38Visual Acuity and Refraction Procedures

A patient's far point is measured at 50 cm in front of the eye. What is the patient's refractive error?

  1. +2.00 D
  2. -0.50 D
  3. -2.00 D Correct answer.
  4. +0.50 D

Explanation

The far point of a myopic eye lies in front of the eye, and its distance in meters gives the reciprocal of the refractive error. A far point at 0.50 m corresponds to -2.00 D. Hyperopic eyes have a far point behind the eye and a positive correction.

Question 39Visual Acuity and Refraction Procedures

Which of the following best describes the purpose of fogging during subjective refraction?

  1. To stimulate accommodation for a more accurate endpoint
  2. To determine the patient's near add
  3. To measure the patient's amplitude of accommodation
  4. To relax accommodation by adding plus power until acuity is slightly reduced Correct answer.

Explanation

Fogging deliberately over-plusses the patient so that acuity is reduced slightly, which relaxes accommodation and prevents it from masking hyperopia or skewing sphere refinement. The endpoint is then approached by reducing plus in controlled steps. This technique improves reliability of the subjective refraction.

Question 40Visual Acuity and Refraction Procedures

During a subjective refraction, the patient's acuity is 20/20 with a sphere of +1.00 D. Adding +0.50 D reduces acuity to 20/25. What does this response most likely indicate?

  1. The patient is under-plussed at +1.00 D
  2. The patient has significant astigmatism
  3. The patient is over-plussed at +1.00 D Correct answer.
  4. The patient requires a near addition

Explanation

Reduction of acuity when plus is added indicates the eye can no longer tolerate additional plus without blur, consistent with the current sphere being at or near the maximum plus accepted. The endpoint of maximum plus for best acuity has been reached. Further plus would over-correct the hyperopia.

Question 41Binocular Vision and Ocular Motility Testing

During cover-uncover testing, the examiner observes the right eye move outward to fixate when the left eye is covered. What does this finding indicate?

  1. A right hypotropia
  2. A right exotropia Correct answer.
  3. A right esotropia
  4. A left hypertropia

Explanation

When the fixating left eye is covered, the right eye takes up fixation. If the right eye must move outward (temporally) to fixate, it was deviated inward relative to the target, meaning it was turned in under binocular conditions. The eye that moves outward to take fixation is therefore esotropic before the cover, so a manifest inward turn of the right eye is present.

Question 42Binocular Vision and Ocular Motility Testing

Which test directly assesses the presence of a suppression scotoma under binocular viewing conditions?

  1. The Hirschberg test
  2. The prism alternate cover test
  3. The Maddox rod test
  4. The Worth 4-dot test Correct answer.

Explanation

The Worth 4-dot test presents dissimilar targets to each eye through red-green filters while both eyes are open, so a patient who fails to report all four lights demonstrates suppression of one eye's image. The other listed tests measure deviation magnitude or corneal light reflex position rather than binocular suppression.

Question 43Binocular Vision and Ocular Motility Testing

A patient reports horizontal diplopia that is worse at distance than at near. Which deviation is most consistent with this pattern?

  1. An exotropia that is greater at distance Correct answer.
  2. An esotropia that increases at near
  3. A convergence insufficiency
  4. A decompensated near phoria

Explanation

Distance symptoms predominating over near symptoms point to a divergence-related problem, and an exodeviation that is larger at distance fits this pattern. Near-predominant symptoms instead suggest a convergence or near-fixation problem.

Question 44Binocular Vision and Ocular Motility Testing

In the Hirschberg test, a corneal light reflex displaced approximately 1 mm from the center of the pupil corresponds to roughly what deviation?

  1. About 30 prism diopters
  2. About 15 prism diopters Correct answer.
  3. About 2 prism diopters
  4. About 45 prism diopters

Explanation

The Hirschberg test uses the rule that each millimeter of reflex displacement from the pupillary center corresponds to approximately 15 prism diopters of deviation. This makes it a rapid gross estimate rather than a precise measurement.

Question 45Binocular Vision and Ocular Motility Testing

During a cover test, the examiner notes that the uncovered eye makes a slow, drifting movement to re-fixate after the cover is removed. This finding is most characteristic of which condition?

  1. An intermittent exotropia
  2. A dissociated vertical deviation
  3. A latent nystagmus Correct answer.
  4. A congenital fibrosis syndrome

Explanation

Latent nystagmus becomes manifest when one eye is occluded and produces a slow drift of the fixating eye with a fast corrective phase on uncovering. The slow drifting re-fixation after removal of the cover is the hallmark of this condition.

Question 46Binocular Vision and Ocular Motility Testing

Which measurement best describes the near point of convergence?

  1. The distance at which the patient first reports blur of a near target
  2. The distance at which a target doubles or the patient reports diplopia as it is brought toward the nose Correct answer.
  3. The prism diopters required to neutralize a near phoria
  4. The amplitude of accommodation measured monocularly

Explanation

The near point of convergence is the closest point at which the patient can maintain single binocular vision as a target is moved toward the nose. It is recorded as the distance at which the patient reports diplopia or the examiner observes a loss of convergence.

Question 47Binocular Vision and Ocular Motility Testing

A patient with an uncorrected hyperopic refractive error shows an esotropia on cover testing. What is the most likely mechanism?

  1. A mechanical restriction of the lateral rectus muscles
  2. A primary divergence excess producing an inward turn
  3. Accommodative convergence driven by the effort to clear the blurred retinal image Correct answer.
  4. A supranuclear palsy of the abducens nucleus

Explanation

Uncorrected hyperopia requires accommodative effort to clear the retinal image, and accommodation is linked to convergence through the AC/A relationship. This excess accommodative convergence can produce an esotropia, which is the basis for accommodative esotropia.

Question 48Binocular Vision and Ocular Motility Testing

In a patient with a suspected superior oblique palsy, the Bielschowsky head tilt test is positive when the hypertropia increases with which head tilt?

  1. Tilt toward the side of the higher eye Correct answer.
  2. Tilt to either side equally
  3. Tilt backward toward the neck
  4. Tilt toward the side of the lower eye

Explanation

In a superior oblique palsy, tilting the head toward the side of the affected eye increases the hypertropia because the ipsilateral superior oblique is the principal intorter and its weakness is unmasked. Therefore the hypertropia is greater on tilt toward the side of the higher eye.

Question 49Binocular Vision and Ocular Motility Testing

During a prism alternate cover test, the examiner places a base-out prism before the eye and the deviation is neutralized. What does this indicate about the deviation?

  1. The deviation is an exodeviation
  2. The deviation is an esodeviation Correct answer.
  3. The deviation is a vertical deviation
  4. The deviation is a torsional deviation

Explanation

Base-out prism shifts the image of the target toward the patient's nose, so it neutralizes an inward (eso) deviation by requiring the eye to turn outward to fixate. A base-in prism would be used to neutralize an exodeviation.

Question 50Binocular Vision and Ocular Motility Testing

A patient reports that the diplopic image from the right eye disappears when the left eye is covered. Which finding does this support?

  1. The patient has a suppression scotoma in the left eye
  2. The patient has a suppression scotoma in the right eye
  3. The right eye's image is the false image Correct answer.
  4. The left eye's image is the false image

Explanation

In diplopia testing, the image that disappears when the fellow eye is covered belongs to the covered eye. Since the right eye's image disappears when the left eye is covered, the right eye is producing the false image, which identifies the deviated eye.