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Anterior Segment 2 > Devlin: Refractive Sx > Flashcards

Devlin: Refractive Sx Flashcards

1
Q

What are the true goals of refractive surgery?

A
  1. Reduce dependence on glasses
  2. CL intolerant
  3. Ideal for 20-40 yo
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2
Q

What is the general concept for refractive sx?

A

Reshapes cornea to create proper focus

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3
Q

What changes to the cornea are made for myopes?

A

Laser flattens cornea

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4
Q

What changes to the cornea are made to hyperopes?

A

Laser steepens cornea

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5
Q

What changes are made to the cornea for astigmats?

A

Laser sphericalizes the cornea

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6
Q

Name the surgical option no longer performed. What was the bad long-term effect of it?

A

Radial Keratotomy (RK)

  • find progressive hyperopia (central flattening) as long-term effect
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7
Q

What are the 3 types of surface ablation methods?

A
  1. PRK
  2. LASEK
  3. Epi-LASEK
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8
Q

What are the 2 types of corneal remolding techniques?

A

Surface Ablation

LASIK

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9
Q

Refractive sx can be divided into what 2 parts?

A
  1. exposing tissue to be ablated

2. ablating the tissue

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10
Q

What does PRK stand for?

A

PhotoRefractive Keratectomy

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11
Q

Is the epithelium preserved in PRK?

A

No

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12
Q

What are the 3 complications of PRK?

A
  1. Anterior Stromal Scarring
  2. Delay in healing
  3. Best VA is 6 wks post op
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13
Q

How is the epithelium removed during PRK?

A

Removal of epithelium via blade/brush

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14
Q

How is the epithelium loosened in LASEK?

A

Epithelium loosened w/ denatured alcohol

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15
Q

When compared to PRK and LASEK, epi-LASIK has what type of performance?

A

Superior performance and results

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16
Q

Where is the epithelium cleaved in Epi-LASIK?

A

Cleaved at Bowman’s membrane

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17
Q

Where does the epithelium attach to if BM is removed?

A

Attaches to anterior stroma

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18
Q

What is used to help healing time in an Epi-Lasik patient?

A

Bandage CLs

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19
Q

When does visual recovery occur in Epi-lasik patients?

A

4-6 wks

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20
Q

Which procedure was the major breakthrough in kerato-refractive surgery?

A

LASIK

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21
Q

Where is the corneal flap made in LASIK? What is the purpose of this?

A
  • corneal flap created in anterior stroma

- preserving epithelium, increasing speed of recovery

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22
Q

When is visual recovery in a LASIK patient?

A

12 hours

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23
Q

What was the original flap creation device?

A

Mechanical Microkeratome

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24
Q

What is a disadvantage of the Femtosecond Laser used to burn a flap layer instead of cutting?

A

Heat generated from laser creates Opaque Bubble Layer (OBL)

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25
Q

What tool is used in all 4 corneal reshaping surgical methods?

A

Excimer Laser - sculpts corneal stroma with microablations to generate new curve

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26
Q

What are the FDA guidelines for Myopia vs. Devlin’s ?

A 
FDA = up to - 14D
Dev = up to - 8D
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27
Q

What are the FDA guidelines for Hyperopia vs. Devlin’s ?

A 
FDA = up to + 6D
Dev = up to +3D
28
Q

What are the FDA guidelines for Astigmatism vs. Devlin’s ?

A 
FDA = up to 6D
Dev = up to 4D
29
Q

T or F: the lower the dioptic value, the more likely for success?

A

True

30
Q

How much stromal tissue is removed per diopter of correction?

A

10-15um

31
Q

What is the K-value change for myopia?

A

1Drefractive = 1D K-value flattening

32
Q

What is the K-value change for hyperopia?

A

1D refrac = 1.2D K-value steepening

33
Q

What are the 3 types of excimer lasers?

A
  1. Broadbeam (worse)
  2. Scanning Slit (smooth)
  3. Flying spot (accurate)
34
Q

What is the goal of wavefront guided lasik?

A

To eliminate higher order aberration from the cornea

35
Q

What is the reality of wavefront guided lasik?

A

Failure lies in the lack of intra-surgical measuring

36
Q

What are the 2 most common and effective surgeries today?

A

LASIK & Epi-LASIK

37
Q

What 3 main tests need to be performed prior to sx?

A
  1. Refraction (dry &wet)
  2. Topography
  3. Pachymetry
38
Q

What pachymetry reading is the “cutoff”

A

< 500um

39
Q

The FDA requires how much residual stromal bed to be left over after sx?

A

250um

40
Q

If a -5D myope pt has 550um cornea and needs a 130 um flap, what is the residual stromal bed?

A

550 - (130+15um(5)) = 345um

41
Q

What are the most critical factors affecting candidacy?

A
  1. Corneal Topography
  2. Corneal Pachs
  3. Spec Rx w/in limits
42
Q

What is the single biggest candidacy debate in refractive sx?

A

Topography

43
Q

What is a major topography sublinical signs of complication?

A

Forme Fruste keratoconus (FFKC)

44
Q

What is the #1 king-term risk of corneal refractive surgery?

A

Ectasia (keratoconus/globus/PMD)

45
Q

What are systemic conditions that are a possible contraindication to sx?

A
  1. Auto-Immune Diseases
  2. Atopic disease (linked to ectasia)
  3. Eye rubbing (leads to ectasia)
  4. Diabetes
46
Q

What is a successful VA in refractive sx patients?

A

20/40 or better

47
Q

Who has the higher regression rate after sx? myopes or hyperopes?

A

Hyperopes, more likely to need enhancement

48
Q

What are the 3 types of intraoperative risks?

A
  1. Free cap
  2. Buttonhole/Thin flap
  3. Decentered ablation
  4. Under/Over Correction
49
Q

Describe a free cap?

A

Microkeratome makes complete pass and entire cornea flap comes off

50
Q

Describe buttonhold/thin flap?

A

Suction loss causin incomplete flap

51
Q

Describe Decentered Ablatin?

A

Pt not positioned properly, not cooperative, results in irregular topography

52
Q

Describe under/over correction?

A

Refraction error due to corneal hydration issue

53
Q

What are the post-operative risks?

A
  1. Stria
  2. Epithelial Ingrowth
  3. DLK
54
Q

What do stria occur from?

A

Eye rubbing or naturally during flap dehydration

55
Q

What 2 ways can stria be dealt with?

A
  1. Massaged out with Weck-Cel sponge

2. Lift flap, smooth, hydrate, replace

56
Q

What % of LASIK patients get epithelial ingrowth?

A

1-2%

57
Q

How can one prevent epithelial ingrowth?

A

Align flap perfection on replacement

58
Q

How can we tx epithelial ingrowths?

A

Lift flap and clean; mitomycin C use is debated

59
Q

What is Diffuse Lamellar Keratitis?

A

Active inflammation within the interface

starts in periphery and migrates toward visual axis

60
Q

When does DLK occur?

A

1-7 days post op

61
Q

How do we tx DLK?

A
  1. Pred Forte q1h
  2. Meldrol Dose Pak
  3. Surgeon lift flap, clean and apply steroids
62
Q

The Visian ICL is only for what type of refractive error? How many diopters? Is it reversible?

A

Myopic (-3D to -16D)

Reversible

63
Q

How large must one’s AC depth be for an ICL? How many endothelial cells?

A

> 3.000

>3,000 cell count

64
Q

What are the 3 main risks associated with the Visian ICL?

A
  1. Cataract formation
  2. Endothelial Cell loss
  3. Glaucoma - pupillary block or angle closure
65
Q

What type of refractive error does the Verisyse-Artisan lens correct for?

A

Myopia, Hyperopia, Astigmatism

66
Q

What are the 2 risks of Verisyse-Artisan lens?

A
  1. Endothelial cell loss

2. Glaucoma - pigment dispersion or narrow angle

Anterior Segment 2 (14 decks)

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