Incisional Techniques

Question 1

Radial incisions - where flattening

Answer 1

in both the meridian of the incision and the one 90° away

Question 2

Tangential (arcuate or linear) - where flattening

Answer 2

in the meridian of the incision and steepening in the meridian 90° (may be equal to or less than the magnitude of the decrease in the primary meridian)

Question 3

coupling

Answer 3

flattening in the meridian of the incision and steepening in the meridian 90° away

Question 4

How deep should be the incision

Answer 4

85%–90% deep

Question 5

In older effect is lower or grater

Answer 5

greater

Question 6

Collagen Shrinkage - what temperature

Answer 6

58°–76°C

Question 7

Thermokeratoplasty and conductive keratoplasty - where

Answer 7

in the midperiphery to cause local collagen contraction with concurrent central corneal steepening

Question 8

Photoablation - laser energy sufficient to break

Answer 8

4 eV per photon or greater

Question 9

Argon-fluoride (ArF) lasers - wavelength

Answer 9

193 nm with 6.4 eV per photon

Question 10

Argon-fluoride (ArF) lasers - advantages

Answer 10

high energy per photon, very low tissue penetrance, capable of great precision

Question 11

femtosecond laser - usage

Answer 11

creating flaps for LASIK and for the SMILE procedure, channels for intrastromal ring segments and for lamellar keratoplasty and PKP

Question 12

femtosecond laser - wavelength

Answer 12

1053-nm infrared beam

Question 13

femtosecond laser - phenomenon

Answer 13

photodisruption, a process by which tissue is transformed into plasma, and the subsequent high pressure and temperature generated lead to rapid tissue expansion and formation of microscopic cavities within the corneal stroma

Question 14

Ho:YAG laser - wavelength

Answer 14

2.13 μm

Question 15

Ho:YAG laser - phenomenon

Answer 15

Photothermal effects with a wavelength of 2.13 μm into the anterior stroma

Question 16

Photothermal effects - for whom

Answer 16

low hyperopia

Question 17

How to reduce glare, halos, and regression with Photoablation

Answer 17

optical zone should be 6 mm or larger

Question 18

Ablation - which layers

Answer 18

Bowman layer and the anterior stroma

Question 19

LASIK - which layers

Answer 19

stromal bed

Question 20

Flaps thickness

Answer 20

80 - 180 μm

Question 21

Broad-beam lasers

Answer 21

larger-diameter 7 mm, slower repetition, high energy, require a small number of pulses to ablate

Question 22

Scanning-slit lasers

Answer 22

narrow-slit, improving the smoothness, allowing for larger-diameter ablation zones

Question 23

Flying spot lasers

Answer 23

smaller-diameter beams (approximately 0.5–2.0 mm), higher repetition rate, majority of today’s lasers

Question 24

Most common aberrations follwing myopic corrections

Answer 24

spherical aberration and coma

Question 25

Wavefront-optimized laser ablation

Answer 25

taking the curvature of the cornea into account and increasing the number of peripheral pulses

Question 26

wavefront-guided

Answer 26

slower, expense of the aberrometer, treat both lower-order and higher-order, pupil-tracking system, treatment of highly aberrated eyes, such as eyes with previous RK or PKP

Question 27

greater tendency toward haze formation

Answer 27

deeper ablations, increased surface irregularity, and prolonged absence of the epithelium

Question 28

What drugs are contraindicated

Answer 28

Isotretinoin, amiodarone, sumatriptan for PRK and LASIK. hormone replacement therapy or antihistamines for PRK

Question 29

Tangential keratotomy and AK - where is incision

Answer 29

at the 7-mm optical zone

Question 30

Tangential keratotomy - use

Answer 30

was used in the past in combination with RK to correct myopic astigmatism

Question 31

AK and LRI - use

Answer 31

AK - post-keratoplasty astigmatism. AK and LRI - astigmatism during or after cataract surgery and IOL implantation, as well as after refractive surgery procedures such as LASIK and PRK

Question 32

When there is a coupling ratio greater than 1.0 - what occurs

Answer 32

hyperopic shift occurs

Question 33

Long, straight, and tangential incisions tend to induce a coupling ratio

Answer 33

greater than 1.0

Question 34

When a correction is less than 2.00 D of astigmatism, the coupling ratio is

Answer 34

typically 1.0

Question 35

when a correction is greater than 2.00 D of astigmatism, the coupling ratio tends to be

Answer 35

greater than 1.0

Question 36

AR or LRI change spherical equivalent?

Answer 36

no

Question 37

LRI - how deep incisions ?

Answer 37

600 μm depth, or 50 μm less than the thinnest pachymetry measurement at the limbus

Question 38

What can happen when moving from an upright to a supine position

Answer 38

15° of cyclotorsion can occur

Question 39

Where to make AK after KP?

Answer 39

in the graft or in the graft–host junction. . When AK incisions are made in the host, the effect is significantly reduced

Question 40

Irregular astigmatism is more common after AK or LRI?

Answer 40

more common with AKs