Accommodation

Question 1

What structures are involved in accommodation

Answer 1

Ciliary body and muscle
Choroid
Iris
Anterior zonules
Posterior zonules
Crystalline lens and lens capsule

Question 2

The ciliary muscle is what kind of muscle

Answer 2

Smooth muscle

Question 3

The PNS has what affect on the ciliary muscles

Answer 3

Contraction

Question 4

The SNS has what affect on the ciliary muscle

Answer 4

Relaxation

Question 5

What are the 3 muscle groups in the ciliary muscle

Answer 5

Longitudinal
Radial
Circular

Question 6

What happens to the ciliary muscle fibers in accommodation

Answer 6

All contract

Causes a gradual rearrangement of the fibers

Question 7

What muscle fibers have the greatest contribution to changing the lens shape during accommodation

Answer 7

Circular fibers

Question 8

What happens to the TM during accommodation

Answer 8

Sclera spur moves posteriorly and enhances flow across the entire trabecular mesh work by opening up flow channels, which increases effective filtration area

Question 9

What happens to the TM during relaxation

Answer 9

The scleral spur moves to its original position. Decrease flow across TM by closing flow channels. Decreases effective filtration area

Question 10

Where do the zonular fibers insert at

Answer 10

Valleys of Kuhnt on the pars plicata of the ciliary body

Question 11

What are the zonules made of

Answer 11

Elastin based fibers

Question 12

What secretes the zonules

Answer 12

Nonpigmented ciliary epithelium

Question 13

What is the function of the zonules

Answer 13

Stabilize the lens

Question 14

What are the zonule groups

Answer 14

Anterior 
    Anterior
    Equatorial
    Posterior
Posterior

Question 15

What is the function of the posterior zonules

Answer 15

Aid in pulling the ciliary muscle back to its unaccommodated state position after accommodation has ceased

Question 16

What is the mechanism of accommodation

Answer 16

Looking at distance the eye is at rest
There is resting tension on the anterior zonules that pull the lens outward and keep it flat.
Contraction of the ciliary body pulls the inner face of the ciliary body forward and places stress on the posterior zonules while releasing tension on the anterior zonules.
The capsule molds the lens into a more spherical shape
Lens diameter decreases and lens thickness increases.
Anterior curvature increases and so does anterior chamber depth

Question 17

What is the mechanism of relaxing accommodation

Answer 17

The elasticity of the ciliary muscle to the choroid and tension on the posterior zonules pulls the ciliary body posterior
Resting tension on anterior zonules is returned
Posterior zonules relax

Question 18

What supplies the major force to accommodate the lens

Answer 18

The lens capsule

Question 19

What does the lens content do

Answer 19

Reduce the rate of capsule movement and retard the extent of change in the lens

Question 20

What is the resting state of accommodation

Answer 20

1.5D of tonic accommodation

Question 21

What are the 3 physiological responses of the accommodative process

Answer 21

Pupillary constriction
Convergence of the eyes
Accommodation

Question 22

What nucleus in important in accommodation

Answer 22

EW nucleus

Question 23

What is presbyopia

Answer 23

Age related loss of accommodation

Question 24

When is presbyopia complete

Answer 24

50 years of age

Question 25

What is the cause of presbyopia

Answer 25

Multifactorial

Question 26

How do you correct presbyopia

Answer 26

Bifocals or contact lenses