Accommodation and Presbyopia

Question 1

What is accommodation?

Answer 1

A dynamic change in the power of the eye

Question 2

What does accommodation provide the eye?

Answer 2

The ability to change the point of focus of the eye from distant to near objects

Question 3

Does the optical power of the lens increase of decrease with accommodation

Answer 3

Increase

Question 4

What unit is accommodation measured in?

Answer 4

Diopteres

Question 5

What is a diopter and how is it measured?

Answer 5

a reciprocal meter

measure of the vergence of light

Question 6

How is accomodation mediated?

Answer 6

◦Contraction of the ciliary muscle
◦Release of zonular tension at the equator
◦“Rounding up” of the lens (force exerted by capsule)

Question 7

How is the increased optical power in accommodation achieved?

Answer 7

Through the increased anterior and posterior lens surface curvatures and increased thickness of the lens

Question 8

Myopes can focus clearly on objects _____ than optical infinity with accommodation

Answer 8

closer

Question 9

Hyperopes can focues clearly on objects at ____ ___ only through an accommodative increase or with + lens

Answer 9

optical infinity

Question 10

What is the refractive index of the cornea?

Answer 10

About 1.376

Question 11

The refractive index of the aqueous humor is about?

Answer 11

1.336

Question 12

Because the refractive indexes of the aqueous humor and cornea are so close the optical affective is?

Answer 12

relatively little

Question 13

The optical power of the cornea comes from?

Answer 13

The change in refractive index and positive radius of curvature

Question 14

the anterior and posterior surface of the lens add or subtract to the optical power of the eye

Answer 14

add

Question 15

The posterior lens surface increases or decreases in curvature and moves backward or forward with accommodation?

Answer 15

Increases

Backward

Question 16

What is the depth of field?

Answer 16

The range over which a target can be moved toward or away from the eye without a perceptible change in blur or focus of the image

Question 17

What is the depth of focus?

Answer 17

Depth of focus is the focusing error that can be tolerated without an appreciable decrease in acuity or change in blur or focus of the image on the retina

Question 18

Depth of focus is dependent on?

Answer 18

Pupil size

Question 19

What does a small pupil say about depth of focus? large pupil?

Answer 19

Small - larger depth of focus

Larger - smaller depth of focus

Question 20

Does the pupil size increase or decrease with accommodation?

Answer 20

Decreases (increasing depth of focus)

Question 21

Does pupil size increase ot decrease with aging? What is this referred to?

Answer 21

Decreases

Senile Miosis

(decreased need for add in presbyopic correction- increased depth of focus)

Question 22

When the eye is at rest focused on distance the resting tension on the zonular fibers spanning the anterior zonule applies what?

Answer 22

An outward directed tension on the lens squator throgh the lens capsule

(holds lens in relatively flattened and unaccommodated state)

Question 23

At rest, the eyes have some residual or resting level of accommodation amounting to approx. _____ D. What is this called?

Answer 23

1.5 D

tonic accommodation (residual)

Question 24

What is the accommodative triad?

Answer 24

◦1. the pupil constricts
◦2. the eyes converge
◦3. the eyes accommodate

Question 25

An accommodative stimulus presented \_\_\_\_\_\_ results in a binocular accommodation and convergence response.

Answer 25

Monocularly

Question 26

A convergence stimulus in one eye results in ____ \_\_\_\_\_, \_\_\_\_\_\_\_, and ______ in both eyes.

Answer 26

Pupil Constriction Convergence Accommodation

Question 27

If a myopic blur is presented to one or both eyes which lens will cause the eyes to accommodate to overcome the imposed defocus?

Answer 27

negative lens

Question 28

If a base-out prism is placed in front of the eye will vergence increase or decrease?

Answer 28

Increase

Question 29

What can accommodation be induced through?

Answer 29

Pharmacologic stimulation (muscarinic cholinergic agostists) (pupil constriction ill also occur but no convergence)

Question 30

Accommodative esotropia most often occurs in?

Answer 30

Uncorrected persons with hyperopia as a consequence of a need to accommodate even to see distance objects in focus

Question 31

What can block accommodation?

Answer 31

Cycloplegia induced byt topical application of muscarinic antagosists

Question 32

The push-up method in accommodation requires the patient to report?

Answer 32

When a near letter chart can no longer be maintained in sharp focus as the chart is gradually brought closer to the eye

Question 33

What is the minus lens to blur method?

Answer 33

◦Placing negatively powered trial lenses in front of one or both eyes to blur a distant letter chart stimulating accommodation ◦ ◦Letter size is minified - problem

Question 34

What are surgical options for persons with presbyopia?

Answer 34

◦Corneal refractive surgery ◦Cataract surgery ◦Accommodative IOLs

Question 35

As we age, there is a (loss/gain) of muscle fibers and (increase/decrease) in connective tissue?

Answer 35

Loss Increase

Question 36

In aging, the contractive force does not (increase/decrease); it (increases/decreases) and is at its max at the age presbyopia manifests

Answer 36

Decrease Increases

Question 37

Where does the inner apex of the unaccommodated ciliary muscle reside in the aging eye?

Answer 37

Further forward and inward toward the anteroposterior axis

Question 38

What is presbyopia?

Answer 38

The age-related loss in accommodative ability; results in nearly complete loss in accommodative ability by age 50

Question 39

How much of accommodative amplitude is lost between ages 15-35?

Answer 39

2/3

Question 40

What is the thickness of the lens capsule at birth and at age 60?

Answer 40

11 um at birth 20 um at age 60 (decrease slightly thereafter)

Question 41

Force transmitted per unit of thickness by ____ at age 60

Answer 41

half

Question 42

What does increased thickness of the lens compensate for?

Answer 42

The loss of elasticity

Question 43

Does the equatorial diameter of the lens increase?

Answer 43

Yes

Question 44

When young lenses are removed from the eye they (do/do not) accommate?

Answer 44

Do

Question 45

When older lenses are removed from the eye they (do/ do not) change in shape

Answer 45

do not

Question 46

How much does the hardness of the lens increase of the life span?

Answer 46

four-fold (doesnt stop at age 50)

Question 47

The lens substance must remain suffiecintly pliable so the capsular foces can act on it to ____ it (\_\_\_\_\_\_) and ______ it (\_\_\_\_\_\_)

Answer 47

Flatten it (unaccommodative) Curve it (accommodative)

Question 48

Lenticular sclerosis

Answer 48

Most commonly articulated explanation for presbyopia lens becomes harder with increasing age

Question 49

Where are the anterior zonular connections in the young lens?

Answer 49

Near the lens equator and exert strong influence on the curvature of the lens

Question 50

Where are the anterior zonular connections in the aged lens?

Answer 50

Farther forward than equator, not effective relaxation of the force with ciliary muscle contraction

Question 51

What does the disaccommodation theory suggest?

Answer 51

Not caused by a failure of the lens to accommodate but instead a gradual failure of the lens to be held in the unaccommodated form at rest

Question 52

What is the multifactorial theory?

Answer 52

Presbyopia results not from any single causal factor, but through global deterioration of accommodative function Presbyopia is not an end point, but a time point in a gradual, progressive continuum of deterioration of the accommodative structures

Question 53

Optical compensation for presbyopes is achieved with?

Answer 53

◦Spectacle lenses ◦Contact lenses ◦Corneal refractive surgical procedures ◦Or artificial intraocular lenses (IOLs).