Optics: Presbyopic Optics And Correction

Question 1

Crystalline lens provides approximately ________ the total static refractive power of the eye

Answer 1

1/3rd

Question 2

Two purposes of the lens:

Answer 2

-combine w cornea to form image on retina
-mechanism for focusing at different lengths

Question 3

Is the crystalline lens active?

Answer 3

Yes

Question 4

The lens is ________ in form

Answer 4

Biconvex

Question 5

What is the diameter of the lens?

Answer 5

9mm

Question 6

What is the thickness of relaxed lens?

Answer 6

3.6mm

Question 7

Anterior radius of the lens is ____ times greater than the posterior

Answer 7

1.7

Question 8

What pattern are the lens fiber cell arranged?

Answer 8

Hexagonal pattern

Question 9

Diameter, thickness, and weight of the lens at birth

Answer 9

Diameter: 6mm
Thickness: 4mm
Weight: 23-25mg

Question 10

What is the thickness of the lens as a teenager? Why does this change happen?

Answer 10

3.4mm , the emmetropization process

Question 11

What is the combined refractive power of the lens?

Answer 11

21.35D

Question 12

What is the accommodated power of the lens?

Answer 12

31.85 D

Question 13

What is a cataract?

Answer 13

Any disturbance in the optical homogeneity of the lens

Question 14

Presbyopia:

Answer 14

The gradual adn progressive age related loss of accommodative amplitude and ultimately due to are related loss in the ability of the lens to undergo accommodative optical changes

Question 15

Who feels the impacts and symptoms of presbyopia the most?

Answer 15

Emmetrope and uncorrected hyperopes

Question 16

Accommodative amplitude at age 10 vs age 50

Answer 16

10 D at age 10, 0D at age 55

Question 17

What happens to the ciliary muscle in presbyopia?

Answer 17

There is a decrease in area and length of the longitudinal and reticular fibers and increase in the area of the circular fibers

Question 18

Does the ciliary muscle still contract in complete presbyopes?

Answer 18

Yes

Question 19

Lens ________ increases linearly with age without a systemic increase in lens diameter

Answer 19

Axial thickness

Question 20

What happens to anterior chamber depth as you get older?

Answer 20

It decreases

Question 21

What happens to the anterior segment length as you get older?

Answer 21

Increases

Question 22

Which region of the lens increases its axial thickness more, cortex or nucleus?

Answer 22

Cortex

Question 23

Changes in the lens with aging:

Answer 23

-accommodation loss
-mass increases
-axial thickness increases
-diameter increases
-anterior surface curvature increases

Question 24

Phakic eye

Answer 24

Eye with the natural lens

Question 25

Aphakic eye

Answer 25

Lens without the natural crystalline lens

Question 26

Pseudophakic eye

Answer 26

Eye contains an intraocular lens

Question 27

What are the uses for IOLs?

Answer 27

-surgical solution for vision loss due to cataract formation -continuous vision solution for presbyopia -accommodating vision or similar to natural crystalline lens

Question 28

Spherical lens work well only for _______ aperture

Answer 28

Small apertures

Question 29

Larger apertures generate higher _____________

Answer 29

Spherical aberration

Question 30

Aspherical lens provides what two things?

Answer 30

-higher image quality -minimal SA

Question 31

With higher powers, the lenses become more ___________, even in aspheric lenses

Answer 31

Spherical

Question 32

What is an A value?

Answer 32

A constant that reflects what the manufacturers have learned about the IOL position

Question 33

What are monofocal IOL used for?

Answer 33

Restoring vision for one area of focus -> usually distance, reading glasses might still be needed

Question 34

What is Multifocal IOL used for?

Answer 34

High-quality vision at multiple distances with enhanced vision at distinct distance customized to suit patient lifestyle —> glasses independence

Question 35

What is an extended depth of focus IOL?

Answer 35

IOLs that provide high quality, continuous vision from near to far and all points in between

Question 36

Bifocal IOL provides what?

Answer 36

Distant and near vision by dividing the energy between near and far

Question 37

Ophthalmic diffractive lenses

Answer 37

A zone plate with kinoform shaped grooves

Question 38

Hybrid lens:

Answer 38

Single refractive lens with a phase plate imbedded on one side of its surfaces

Question 39

Local grating spacing in diffractive lens design determines the __________

Answer 39

Ray direction (spacing progressively gets smaller from center to edge)

Question 40

Local step height of diffractive lens design determines the _________________ of light

Answer 40

Diffraction efficiency (how much light put into the add portion)

Question 41

The image quality of the ADD power is ________ than the base power, meaning….

Answer 41

Less than, visual acuity and energy for near vision is less than the far vision

Question 42

Multifocal IOL claim to provide decent continuous vision but cause:

Answer 42

-decreased image quality -unwanted phenomenon like glare or halos -minimal success

Question 43

Dysphotopsia:

Answer 43

Unwanted patterns onto the retina that affect the visual performance by obscuring relevant retinal image

Question 44

Positive dysphotopsia:

Answer 44

Bright artifacts onto the retina

Question 45

Negative dysphotopsia:

Answer 45

Blockage of light onto the retina

Question 46

Extended range of vision IOL or depth of focus IOl provides…

Answer 46

Continuous vision and minimizes unwanted phenomena at the same time

Question 47

What is the holy grail of IOL?

Answer 47

Accommodative IOL

Question 48

What does the accommodative IOL do?

Answer 48

-mimics the natural lens behavior -provides additional 1D of vision compared to monofocal lens

Question 49

What has developed the most effective accommodative-diaccommodative IOL at the preclical level?

Answer 49

Z lens LLC

Question 50

Glistenings cause __________ which result in a reduction in image contrast

Answer 50

Light scatter

Question 51

Current challenges in the IOL industry:

Answer 51

-smaller incision (under 2mm) -posterior capsule opacification (lens epithelial cell growth, can be removed with YAG laser)