L16

Question 1

How does the crystalline lens change during accommodation in a young eye?

Answer 1

It increases in thickness and power to focus on near objects.

Question 2

What is the prevailing theory of accommodation?

Answer 2

Helmholtz’s theory: the ciliary muscle contracts, reducing zonular tension, allowing the lens to become more convex for near focus.

Question 3

What happens to the lens and zonules in the unaccommodated eye?

Answer 3

The ciliary muscle is relaxed, zonules are under tension, and the lens is flatter for distance vision.

Question 4

What happens to the lens and zonules during accommodation?

Answer 4

The ciliary muscle contracts, zonular tension decreases, and the lens assumes a more powerful, rounded shape for near vision.

Question 5

Which part of the lens shows the greatest steepening during accommodation?

Answer 5

The anterior surface.

Question 6

What is the near vision triad?

Answer 6

Accommodation, convergence, and pupil constriction (miosis).

Question 7

How are accommodation and convergence linked?

Answer 7

They are synergistically controlled through the mid-brain (Edinger-Westphal nucleus) and higher centers.

Question 8

What is the autonomic control of the ciliary muscle?

Answer 8

Parasympathetic fibers of the third cranial nerve (N III) stimulate contraction (accommodation); sympathetic fibers (beta 2 receptors) inhibit contraction (relaxation).

Question 9

What are the types of accommodation?

Answer 9

Tonic, convergence, proximal, reflex, and voluntary accommodation.

Question 10

What is tonic accommodation?

Answer 10

The level of accommodation present when the eye is relaxed and there is no stimulus.

Question 11

What is convergence accommodation?

Answer 11

Accommodation stimulated by convergence of the eyes.

Question 12

What is proximal accommodation?

Answer 12

Accommodation stimulated by awareness of a near target.

Question 13

What is reflex accommodation?

Answer 13

An involuntary response to blur to maintain a clear image.

Question 14

What is voluntary accommodation?

Answer 14

Accommodation that can occur independently of a target.

Question 15

What is amplitude of accommodation (AOA)?

Answer 15

The maximum amount of accommodation an individual can exert.

Question 16

How does amplitude of accommodation change with age?

Answer 16

It declines with age, reaching near zero by age 50.

Question 17

What is the far point of the eye?

Answer 17

The position where an object’s image is focused on the retina when the eye is not accommodating.

Question 18

Where is the far point in emmetropia?

Answer 18

At optical infinity.

Question 19

Where is the far point in myopia?

Answer 19

A finite distance in front of the eye.

Question 20

Where is the far point in hyperopia?

Answer 20

A virtual point behind the eye; only converging light can be focused on the retina.

Question 21

What is the range of accommodation?

Answer 21

The distance between the far point and the near point of accommodation.

Question 22

What is the most common clinical test for amplitude of accommodation?

Answer 22

The push-up/pull-down method using the RAF rule.

Question 23

How is the push-up/pull-down method performed?

Answer 23

Move a reading card toward the patient until blur is reported (push-up), then away until clear again (pull-down); average both values.

Question 24

What is the difference between monocular and binocular amplitude of accommodation?

Answer 24

Binocular amplitude is usually 1–2D higher than monocular.

Question 25

What can artificially raise the measured amplitude of accommodation?

Answer 25

Depth of focus and increasing letter size as the card is brought closer.

Question 26

What is the minus lens technique for measuring accommodation?

Answer 26

Minus lenses are added at a fixed near distance until sustained blur occurs; the total lens power plus the stimulus dioptric value gives the amplitude.

Question 27

What are signs and symptoms of presbyopia?

Answer 27

Blurred near vision, eyestrain, headaches around the eyes, temples, or forehead.

Question 28

What are the main theories for the development of presbyopia?

Answer 28

Biomechanical changes in the lens and capsule, changes in the ciliary muscle, and geometric changes in lens shape/size.

Question 29

How does the crystalline lens change with age?

Answer 29

It increases in thickness, curvature of the anterior surface increases, refractive index decreases, and elasticity of the anterior capsule declines.

Question 30

Does the ciliary muscle weaken with age?

Answer 30

No, the ciliary muscle retains its ability to contract throughout life.

Question 31

At what age does presbyopia usually occur?

Answer 31

Typically between 40–45 years; accommodation is near zero by about 55 years.

Question 32

How is presbyopia corrected?

Answer 32

With positive (plus) converging lenses for near tasks, provided as single vision, bifocal, varifocal spectacles, contact lenses, or intraocular lenses.

Question 33

What are the types of spectacle corrections for presbyopia?

Answer 33

Single vision, bifocals, and varifocals.

Question 34

What are the types of contact lens corrections for presbyopia?

Answer 34

Single vision (monovision) and progressive contact lenses.

Question 35

What are intraocular lens (IOL) options for presbyopia?

Answer 35

Multifocal IOLs, accommodating IOLs, or monovision with IOLs.