Ciliary Muscle and Zonular Fibers Quiz
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Questions and Answers

Who was the first to demonstrate that changes in the crystalline lens were responsible for the changes in focus?

  • Bowman & Burke
  • Ariette Acevedo, O.D.
  • Thomas Young (correct)
  • Finchman
  • Which type of fibers in the ciliary muscle originate in the scleral spur and insert into the equatorial portion of the suprachoroid?

  • Radial fibers
  • Circular fibers
  • Longitudinal (meridional) fibers (correct)
  • Longitudinal (meridional) and Radial fibers
  • Who described the ciliary muscle as occupying most of the ciliary body and having the shape of a 'prismatic ring' tha consists in 3 fibers(longitudinal, radial,circular)?

  • Ariette Acevedo, O.D.
  • Thomas Young
  • Bowman & Burke
  • Finchman (correct)
  • What did Bowman & Burke discover in 1847 that is responsible for the lens power changes during accommodation?

    <p>Ciliary muscle</p> Signup and view all the answers

    What is the main function of the ciliary muscle during accommodation?

    <p>To change the lens power</p> Signup and view all the answers

    What is the shape of the ciliary muscle as described by Finchman in 1937?

    <p>Prismatic ring</p> Signup and view all the answers

    What are the three types of fibers that make up the ciliary muscle?

    <p>Longitudinal, Radial, Circular</p> Signup and view all the answers

    Who identified the ciliary muscle as responsible for the lens power changes during accommodation?

    <p>Bowman &amp; Burke</p> Signup and view all the answers

    When there is a change in dioptric power of the crystalline lens to have and maintain an in-focus retinal image of an object in the fovea, what process is occurring?

    <p>Accommodation</p> Signup and view all the answers

    What is responsible for moving the eyes from the anatomical position of rest to a more convergent position?

    <p>Tonic convergence</p> Signup and view all the answers

    Which type of prism produces convergence?

    <p>Base Out (BO) prism</p> Signup and view all the answers

    What is used to calculate the amplitude of convergence?

    <p>Near point of convergence (NPC) and interpupillary distance (IPD)</p> Signup and view all the answers

    What is measured binocularly to determine the ability to converge while maintaining fusion?

    <p>Near Point of Convergence (NPC)</p> Signup and view all the answers

    What should be done if a patient does not report blur but experiences double vision during NPC testing?

    <p>The target should be moved back</p> Signup and view all the answers

    What does the NPC test record the distance at which the patient reports?

    <p>Blur, double vision, and single vision</p> Signup and view all the answers

    What are common errors in NPC testing?

    <p>Convergence insufficiency (CI) and convergence excess</p> Signup and view all the answers

    What is the most common NPC error?

    <p>Relying on subjective measurements</p> Signup and view all the answers

    What does Base In (BI) prism produce?

    <p>Divergence</p> Signup and view all the answers

    What is responsible for the ability to converge while maintaining fusion?

    <p>Fusional convergence</p> Signup and view all the answers

    Which structure consists of three bundles: anterior, equatorial, and posterior?

    <p>Ciliary muscle</p> Signup and view all the answers

    What is part of the ciliary muscle structure?

    <p>TM scleral spur</p> Signup and view all the answers

    What creates the vitreous base?

    <p>Fibers from pars plana of the ciliary body into the vitreous body</p> Signup and view all the answers

    What are the changes during accommodation?

    <p>Pupil constriction, lens movement, and choroid displacement</p> Signup and view all the answers

    What allows the anterior lens surface to become highly curved during accommodation?

    <p>Variation in lens capsule thickness</p> Signup and view all the answers

    What is the amplitude of accommodation based on?

    <p>Far and near points of accommodation</p> Signup and view all the answers

    What is used to evaluate the amplitude of accommodation?

    <p>Near point of accommodation (NPA)</p> Signup and view all the answers

    What is convergence mediated by?

    <p>MR muscle and Oculomotor Nerve Inferior Division</p> Signup and view all the answers

    What effect do minus lenses have on convergence and accommodation?

    <p>Cause more convergence and require more accommodation</p> Signup and view all the answers

    What happens to the age-related expected amplitude of accommodation?

    <p>Decreases with age</p> Signup and view all the answers

    What effect do plus lenses have on convergence and accomodation

    <p>Cause more divergence and require less accommodation</p> Signup and view all the answers

    Study Notes

    Ciliary Muscle and Zonular Fibers

    • Ciliary muscle has radial and zonular fibers, with the zonular fibers consisting of three bundles: anterior, equatorial, and posterior.
    • Schlemm’s canal and TM scleral spur are part of the ciliary muscle structure.
    • The ciliary body has fibers forming a dense meshwork and extending into the vitreous, creating the vitreous base.
    • Changes during accommodation include pupil constriction, lens movement, and choroid displacement.
    • The lens capsule's thickness varies, allowing the anterior lens surface to become highly curved during accommodation.
    • Accommodation range and amplitude are based on the far and near points of accommodation.
    • The amplitude of accommodation is the difference between the dioptric values of the near and far points of accommodation.
    • Near point of accommodation (NPA) is used to evaluate the amplitude of accommodation, and the procedure is performed monocularly.
    • Convergence is the movement of the eyes turning inward, mediated by the MR muscle and Oculomotor Nerve.
    • Minus lenses cause more convergence and require more accommodation, while plus lenses cause more divergence and require less accommodation.
    • The age-related expected amplitude of accommodation decreases with age, as per Donder’s table for age.
    • Hofstetter’s formula provides the expected amplitude of accommodation based on age.

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    Description

    Test your knowledge of the ciliary muscle and zonular fibers with this quiz. Explore topics such as accommodation, changes during lens movement, and age-related changes in the amplitude of accommodation. Delve into the structure and function of the ciliary muscle and its role in vision.

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