Binocular Vision Lecture 7
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Questions and Answers

What is the accommodative lag if the accommodative stimulus is 2.50D and the accommodative response is measured at 1.50D?

  • 1.00D
  • 1.50D (correct)
  • 0.50D
  • 2.00D

    • If a retinoscope needs to be positioned 1 meter away from a patient for a neutral reflex, what is the accommodative response in diopters?

  • 2.00D
  • 1.50D
  • 1.00D (correct)
  • 0.50D

    • What does an accommodative lag greater than +1.00D suggest about a patient's condition?

  • Normal accommodation
  • Ocular muscle imbalance
  • Accommodative spasm
  • Accommodative insufficiency (correct)

    • If a patient shows an accommodative lead, what condition might they be experiencing?

    <p>Accommodative spasm</p> Signup and view all the answers

    For a near target located at 40 cm, what is the correct accommodative stimulus?

    <p>2.50D</p> Signup and view all the answers

    What is the near point of convergence (NPC) used to measure?

    <p>The closest point where binocular single vision is maintained</p> Signup and view all the answers

    Which of the following is an essential consideration when measuring the near point of convergence?

    <p>Using near correction if the patient is presbyopic</p> Signup and view all the answers

    What is indicated by a near point of convergence greater than 7.5 cm?

    <p>Convergence insufficiency</p> Signup and view all the answers

    What characterizes a successful jump convergence test?

    <p>Smooth and prompt movements of both eyes</p> Signup and view all the answers

    What should the distance target be for the jump convergence test?

    <p>One line above the visual acuity of the worst eye</p> Signup and view all the answers

    What does pursuit convergence primarily involve?

    <p>Moving an object slowly towards the eyes</p> Signup and view all the answers

    How is the jump convergence test recorded if eye movements are slow or jerky?

    <p>Jump poor to 15 cm</p> Signup and view all the answers

    Why might a patient not recognize diplopia during NPC testing?

    <p>They may not be aware of visual changes</p> Signup and view all the answers

    What aids in determining the NPC when a patient cannot recognize diplopia?

    <p>Observing when one eye diverges from the target</p> Signup and view all the answers

    What describes the aim of the near vision triad?

    <p>To evaluate the synkinetic actions related to near vision</p> Signup and view all the answers

    What is the primary purpose of the push-up test for amplitude of accommodation?

    <p>To determine the closest point of clear vision maintained</p> Signup and view all the answers

    Which method uses ±2.00DS flippers to assess a patient’s dynamic accommodation?

    <p>Accommodative facility</p> Signup and view all the answers

    During the push-up test, how should the patient indicate when the word becomes blurry?

    <p>By verbally stating it</p> Signup and view all the answers

    What does a patient's inability to accommodate when using dynamic retinoscopy suggest?

    <p>Accommodative lag</p> Signup and view all the answers

    How is the amplitude of accommodation calculated from the push-up test?

    <p>The average of blur and recovery points</p> Signup and view all the answers

    What is the typical age-related expected amplitude of accommodation for a 30-year-old patient?

    <p>9.50 Dioptres</p> Signup and view all the answers

    If a patient’s recorded accommodative lag is greater than +1.00 DS, what condition might be expected?

    <p>Accommodative insufficiency</p> Signup and view all the answers

    Which of the following is a part of the dynamic retinoscopy process?

    <p>Neutralizing the reflex with lenses</p> Signup and view all the answers

    What does the accommodative facility test measure in addition to the rate of change?

    <p>The total amount of accommodation</p> Signup and view all the answers

    What indicates that binocular amplitude of accommodation should be greater than monocular readings?

    <p>Enhanced depth of focus in binocular vision</p> Signup and view all the answers

    During the dynamic retinoscopy, a neutral reflex indicates what condition?

    <p>Perfect accommodation</p> Signup and view all the answers

    Which method allows the examiner to assess accommodative lag by moving the retinoscope?

    <p>Nott method</p> Signup and view all the answers

    What factor can increase the depth of focus during accommodation assessment?

    <p>Small pupil size</p> Signup and view all the answers

    Study Notes

    Binocular Vision - Lecture 7

    • Lecture focuses on convergence and accommodation
    • Students will learn to measure near point of convergence and jump convergence in patients.
    • Students will also learn to measure accommodation using various methods.

    The Near Vision Triad

    • The near vision triad encompasses the synkinetic actions of accommodation, convergence, and pupil response.
    • These actions occur together during near vision.
    • A later section of the lecture will delve deeper into the pupils.

    Convergence

    • Problems with convergence can lead to near-vision issues.
    • Two key types of convergence movements are:
      • Pursuit convergence: Moving an object slowly towards the eyes.
      • Jump convergence: Changing fixation to an object at a different distance.

    The Near Point of Convergence (NPC)

    • NPC is a measure of pursuit convergence.
    • It's defined as the closest point where binocular single vision is still maintained.
    • Measurement is taken from the nose in centimeters.

    How to Measure NPC

    • Routine testing is crucial.
    • Room lights should be on.
    • Use near correction if necessary (for presbyopia).
    • Common targets include the RAF line or a pen tip.
    • Hold the target slightly below primary position for natural near-vision simulation.
    • Instruct the patient to tell you when the target becomes double.
    • Explain that blur is not a factor for recording.
    • Move the target towards the patient's nose.
    • When diplopia or divergence is reported, note the distance in centimeters.
    • If the patient can converge to their nose, record as "NPC: to nose."
    • Otherwise, record in centimeters (using the RAF rule's centimeter scale).

    Jump Convergence Test

    • This measures the ability to quickly switch focus between targets with differing convergence demands.
    • The test is subjective, evaluating movement speed and quality.
    • To perform:
      • Use distance target (letter chart) one line above worst eye acuity
      • Use pen tip 15cm away from patient's primary position as near target
      • Have patient repeatedly switch fixation between the targets
    • If both eyes move smoothly and quickly, record as "Jump good to 15 cm."
    • If movement is jerky or slow, record as "Jump poor to 15 cm."
    • If one eye shows no movement, record as "No jump to 15 cm."
    • Note that over-convergence followed by corrective movement is a normal response.

    Accommodation

    • Accommodation is central to near-vision issues.
    • Several assessment methods are utilized.

    Methods For Assessing Accommodation

    • Clinically, common methods include:

      • Push-up test for amplitude of accommodation
      • Accommodative facility tests
      • Dynamic retinoscopy

    • In research settings, methods such as:

      • Defocus curves (covered in OPT107).
      • Open field auto-refractometry
      • Open field aberrometry are used

    Push-up test for amplitude of accommodation

    • A subjective measurement of accommodation impacted by depth of focus.
    • Defined as the closest point where focus remains maintained.
    • Measured in diopters from the nose.
    • Procedure:
      • Measure the right eye first (occluding the left).
      • Select the smallest readable word.
      • Slowly move it towards the patient.
      • Ask them to report when it blurs; that's the blur point.
      • Note the value in diopters.
      • Move the target back until it clears again (recovery point); note this value in diopters.
      • The average of the two values represents the accommodation amplitude.
      • Repeat for the other eye and binocularly.

    Push-up test for amplitude of accommodation Results

    • Compares results to expected ranges based on patient age.
    • Patients with greater depth of focus show better accommodation amplitudes.
    • If AOA is significantly lower than expected (~1.50 Diopters or greater) it suggests accommodative insufficiency.
    • Expected values vary with age and are based on Hofstetter's formula (a relevant formula referenced by the notes).

    Accommodative Facility

    • Measures the rate of change of accommodation.
    • It doesn't measure the total amount of accommodation; instead, it assesses how quickly an accommodative response changes.
    • It is a valuable tool for identifying accommodative issues.
    • Requires using ±2.00DS flippers.
    • To perform:
      • Place the distance target at 40cm from the patient and their distance correction as appropriate.
      • Direct patients to stare at the smallest text they can comfortably read.
      • Start with +2.00DS lenses infront of the eye and swap to -2.00Ds. Have patient tell you when words are clear again.
      • Cycle between the two powers and record the number of complete cycles per minute (cpm).

    Dynamic Retinoscopy

    • Used to assess both distance and near vision.
    • Two techniques exist:
      • Estimate technique (MET)
      • Nott method

    Dynamic retinoscopy - MET

    • The target should be an accommodative stimulus (letters) at 40cm.
    • The lights should be dim enough to see the reflex but bright enough for the patient to see the stimulus.
    • The patient's distance correction should be in place.
    • Do not fog the other eye.

    Dynamic Retinoscopy - NOTT Method

    • Target stays at 40cm
    • Move the retinoscope instead of the lenses to adjust for any accommodative lag or lead.
    • Record movements in diopters.

    Homework

    • Students are assigned reading material in specific chapters from textbooks on Binocular Vision Assessment and Ophthalmic Clinical Procedures.

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    Related Documents

    OPT503 Lecture 7 Handout PDF

    Description

    This quiz covers key concepts from Lecture 7 on binocular vision, focusing on convergence, accommodation, and the near vision triad. Students will learn different measurement techniques and understand the significance of the near point of convergence in clinical practice.

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