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?

Ciliary muscle Signup and view all the answers

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

To change the lens power Signup and view all the answers

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

Prismatic ring Signup and view all the answers

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

Longitudinal, Radial, Circular Signup and view all the answers

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

Bowman & Burke 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?

Accommodation Signup and view all the answers

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

Tonic convergence Signup and view all the answers

Which type of prism produces convergence?

Base Out (BO) prism Signup and view all the answers

What is used to calculate the amplitude of convergence?

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

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

Near Point of Convergence (NPC) Signup and view all the answers

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

The target should be moved back Signup and view all the answers

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

Blur, double vision, and single vision Signup and view all the answers

What are common errors in NPC testing?

Convergence insufficiency (CI) and convergence excess Signup and view all the answers

What is the most common NPC error?

Relying on subjective measurements Signup and view all the answers

What does Base In (BI) prism produce?

Divergence Signup and view all the answers

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

Fusional convergence Signup and view all the answers

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

Ciliary muscle Signup and view all the answers

What is part of the ciliary muscle structure?

TM scleral spur Signup and view all the answers

What creates the vitreous base?

Fibers from pars plana of the ciliary body into the vitreous body Signup and view all the answers

What are the changes during accommodation?

Pupil constriction, lens movement, and choroid displacement Signup and view all the answers

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

Variation in lens capsule thickness Signup and view all the answers

What is the amplitude of accommodation based on?

Far and near points of accommodation Signup and view all the answers

What is used to evaluate the amplitude of accommodation?

Near point of accommodation (NPA) Signup and view all the answers

What is convergence mediated by?

MR muscle and Oculomotor Nerve Inferior Division Signup and view all the answers

What effect do minus lenses have on convergence and accommodation?

Cause more convergence and require more accommodation Signup and view all the answers

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

Decreases with age Signup and view all the answers

What effect do plus lenses have on convergence and accomodation

Cause more divergence and require less accommodation 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.