Laser Vision

Question 1

What do lasers do

Answer 1

Evaporate, melt, break down tissue

Question 2

The light emitted from a laser is _____________, that is, of one wavelength (color)

Answer 2

Monochromaticity

Question 3

Properties of laser

Answer 3

• monochromatic
• directional
• coherent

Question 4

What are we concerned about in the 4 basic interactions of light when it comes to lasers?

Answer 4

Absorption

Question 5

What is the number one ability of the ophthalmic lasers

Answer 5

Ability to be focused and absorbed by collagen

Question 6

What are some things lasers are used for in ophthalmology

Answer 6

• corneal refractive surgery
• retina (photocoagulation)
• lens (cataract)
• Iris (glaucoma)

Question 7

To open up an pacified lens capsule resulting from prior extracapsular cataract surgery

Answer 7

Posterior capsulotomy

Question 8

Removal of corneal tissue by high energy photon directly breaking molecular bonds with sufficient photon energy

Answer 8

PhotoAblation by Excimer Laser

Question 9

What is the photon energy of Excimer Laser

Answer 9

193nm, 6.4 eV energy

Question 10

Biggest risk of lasers

Answer 10

Not reversible

Question 11

Importance of pulsed laser

Answer 11

Molecular breakdown

Question 12

The nano-second pulsed laser

Answer 12

Makes craters here, doesn’t melt!

Question 13

What does lasik stand for

Answer 13

Laser-assisted-in-situ keratomileusis

Question 14

Steps of LASIK

Answer 14

1. Flap created in 100 microns of cornea
2. Lift flap
3. Excimer laser ablation

Question 15

Why is LASIK better for the patient than PRK?

Answer 15

LASIK goes underneath the epithelium and then puts the epithelium back over it for protection. PRK strips the top most layer, causing a lot of pain for patient in the first few days

Question 16

What does SMILE stand for

Answer 16

Small-incision lenticulate extraction

Question 17

Steps of SMILE

Answer 17

1. Lamellar cut
2. Lenticular creation
3. Lenticular separation
4. Lenticule removal
5. Reshape cornea

NO LASER

Question 18

To correct myopia, we want

Answer 18

Less optical power

Question 19

Less corneal power means

Answer 19

Decreased corneal curvature (flatter)

Question 20

What we want when you correct myopia with laser-vision correction

Answer 20

Less optical power and decreased curvature

Question 21

What we can do to correct myopia in laser-vision correction

Answer 21

Flatten the cornea

Remove the central tissue

Question 22

What part of the eye do we hit with the laser?

Answer 22

Optical zone

Question 23

What is the golden standard for laser surgery

Answer 23

Ablation depth= (optical zone)^2 x ((myopia correction)/3)

Question 24

To correct myopia we want

Answer 24

Less optical power

Question 25

Less corneal power means

Answer 25

Decreased corneal curvature (flatter)

Question 26

What do we want when correcting myopia

Answer 26

``` Less optical power Decreased curvature (center) ```

Question 27

What can we do to correct myopia

Answer 27

Flatten the cornea | Remove the central tissue

Question 28

What part of the cornea do we want to flatten when laser correcting for myopia

Answer 28

Optical zone that is the size of a scoptopic pupil

Question 29

What shape do we move from the cornea when we correct for myopia

Answer 29

Positive meniscus, reduced optical power

Question 30

Munnerlyn formula

Answer 30

Ablation depth= (optical zone)^2 x ((myopia correction)/3)

Question 31

For hte same myopia correction, consider increasing the optical zone by a factor of the square root of 2. The maximum ablation depth...

Answer 31

Increases by a factor of 2

Question 32

Two myopic eyes, -2.00 and -6.00. The maximum ablation depth in the -6.00 eye, compared to the -2.00 eye is

Answer 32

More by a factor of 3

Question 33

Pre op and post op LASIK corneal curvature in myopia

Answer 33

Post op the corneal curvature will be flatter in someone being corrected for myopia

Question 34

To correct hyperopia, we want

Answer 34

More optical power

Question 35

More corneal power means

Answer 35

Increased corneal curvature (steeper)

Question 36

What do we want when correcting for hyperopia?

Answer 36

``` More optical power Increased curvature (center) ```

Question 37

What can we do when laser correcting for hyperopia

Answer 37

Steepen the cornea | Remove peripheral tissue

Question 38

What is the shape of the tissue that is removed from the hyperopic eye during laser correction?

Answer 38

Minus meniscus

Question 39

What does the ablation profile look like in hyperopia post op

Answer 39

Doughnut

Question 40

What happens to the CCT in hyperopia after laser surgery?

Answer 40

Nothing, the CCT is the same because the peripheral tissue is what was removed

Question 41

The corneal curvature went from 41.5 to 49.9, what is the degree of hyperopia that was corrected?

Answer 41

6-7 degrees of hyperopia