Contact Lenses Iii Mt 2 - Keratoconus

Front 1

K-conus = inflam or non-inflam?

Back 1

non-inflammatory

Front 2

Where is K-conus localized?

Back 2

Ectasia in central or inferior cornea

Front 3

T/F - CLEK was an experimental study funded by the NEI involving an 8-year follow-up.

Back 3

False - observational study

Front 4

K-conus age of onset?

Back 4

Puberty

Front 5

K-conus progressive until...

Back 5

3rd to 4th decade

Front 6

Earlier onset of K-conus = (more/less) severe?

Back 6

more

Front 7

K-conus more prevalent in males or females?

Back 7

Relatively equal incidence (CLEK sample = 56.4% male, 43.6% female)

Front 8

K-conus = symmetrical or asym?

Back 8

Asymmetrical

Front 9

CLEK survey = __% diagnoses between ages __ and __ years.

Back 9

90%, 10, 39

Front 10

CLEK survey: mean age of diagnosis = ___.

Back 10

27.3 ± 9.5 yrs

Front 11

CLEK survey: __% of sample less than 50 years of age.

Back 11

98.7%

Front 12

K-cone VA: __% were 20/__ or better thru CLs
__% were 20/__ or better through manifest refraction.

Back 12

88%, 20/40
58%, 20/40

Front 13

What pigmentation is involved with K-cones?

Back 13

Fleischer's Ring - usually at base of cone, iron deposit; easier to find when dilated

Front 14

What three main signs are involved with K-conus?

Back 14

- Fleischer's Ring: iron deposits at base of cone
- Vogt's Striae: "stretch marks", different from striae in edema b/c mostly (not always) vertical and see few.
- Scars: cause unk (possibly eye rubbing or cone itself?)

Front 15

What is the most common bilat sign of K-conus?

Back 15

Fleischer's ring (bottom left pg 3)

Front 16

What is the most common unilat sign of K-conus?

Back 16

Vogt's Striae (bottom left pg 3)

Front 17

What is the hereditary pattern of K-conus?

Back 17

AD w/ variable penetrance

Front 18

CLEK study sample showed __% reported a family Hx of K-conus at baseline (parent, sibling, child, aunt, or uncle)

Back 18

13.5%

Front 19

What behavior is commonly assoc w/ K-conus? What is the prevalence of this behavior in K-cones?

Back 19

Eye rubbing
49% both eyes
1.8% rub only one eye vigorously
3.2% unsure whether they rubbed their eyes

Front 20

CLEK study: Hay fever or allergies = __%

Back 20

53

Front 21

CLEK study: Asthma = __%

Back 21

15

Front 22

CLEK study: Atopic dermatitis = __%

Back 22

8

Front 23

What is the prevalence of atopy in the general population?

Back 23

10-20%

Front 24

What is Munson's Sign?

Back 24

When the cornea of a K-cone pushes enough on the lower lid to make the lid protrude when looking down.

Front 25

T/F - Blindness can occur with K-conus.

Back 25

False

Front 26

Average age of Dx K-conus = __ years old, based on CLEK.

Back 26

27.3

Front 27

T/F - LASIK is ok for K-cones.

Back 27

False - cannot do LASIK in K-cones due to thin cornea

Front 28

What is the NKCF?

Back 28

National Keratoconus Foundation

Front 29

What is the primary mode of correction for mild K-conus?

Back 29

spectacles

Front 30

T/F - CLs can stop the progression of K-conus.

Back 30

False

Front 31

What RGP fitting philosophy is best for achieving a "successful" fit with K-cones?

Back 31

Fit flat - touch cone apex

Front 32

Which RGP fitting philosophy is best for less disruption to the cone apex in K-cones?

Back 32

Fit steep - less rubbing on apex therefore less scarring

Front 33

Which RGP fitting philosophy is best for longer wear time in K-cones?

Back 33

Fit flat - more peripheral clearance allows better tear exchange vs fitting steep

Front 34

T/F - An "ideal" RGP fit on a K-cone involves a sag height of BC that is less than the sag height of the cornea.

Back 34

False - sag height of BC to EQUAL or SLIGHTLY EXCEED sag height of cornea

Front 35

T/F - An "ideal" RGP fit on a K-cone involves no excessive areas of tear/debris pooling under the OZ.

Back 35

True

Front 36

What does FDACL stand for in K-cone RGP fitting? What is the significance?

Back 36

First Definite Apical Clearance Lens - want to find the flattest lens that will result in AC (then eventually fit the steepest AT lens).

Front 37

What are the three main goals for K-cone RGP fits?

Back 37

1) Feather "three point" touch
2) Minimize tear pooling
3) Maximize periph clearance

Front 38

How do you extend your keratometer's range for a K-cone?

Back 38

Use +1.25 D and add 8.00-9.00D to the drum reading.
(+2.25D add = ~16.00D to drum reading)

Front 39

T/F - It is possible to judge the amount of bearing (e.g. "1.00D flat") based on the FP in K-cone RGP fits.

Back 39

False - can't tell if too flat since the amount of bearing can be very similar between two lenses of different BCs (due to shape of cone apex)

Front 40

What is a good strategy to minimize the area of tear pooling around the base of the cone?

Back 40

Decrease the OZ (see figure middle right pg 8)

Front 41

K-cone RGP power is usually (plus/minus)?

Back 41

minus

Front 42

K-cone RGP OAD is usually (smaller/larger) vs typical RGPs? Why?

Back 42

smaller (better for tear exch)

Front 43

K-cone RGP OZ is usually (smaler/larger) vs typical RGPs?

Back 43

smaller

Front 44

How do you determine the SCr in K-cone RGPs?

Back 44

Typically given as normal since mid-periph and periph usually unaffected, but change SCr based on amount of periph clearance seen (want to maximize)

Front 45

What kind of blend is indicated for K-cone RGPs?

Back 45

medium

Front 46

What Dk is typical for K-cone RGPs?

Back 46

DK ≥60

Front 47

T/F - There is usually no relation between your subjective refraction and CLP in K-cone RGPs.

Back 47

True - but typically CLP is more minus

Front 48

T/F - The Rose K RGP design minimizes the amount of tear pooling around the base of the cone.

Back 48

True

Front 49

In rose K, OZ (incr/decr) as BC is prescribed steeper.

Back 49

decr

Front 50

For Rose K fits, what BC should you start with when fitting your K-cone patient?

Back 50

Avg K to 0.2mm steeper for initial lens

Front 51

In Rose K, the BC is (sphere/aspheric), and the PC is (sphere/aspheric)

Back 51

sphere, aspheric

Front 52

Rose K2 typically has (smaller/larger) OZs. What is the significance of this?

Back 52

larger; improved night vision, decr image ghosting and aberrations

Front 53

What K-cone RGP involves computer-assisted fitting?

Back 53

Keratoconus Bi-Aspheric (KBA)

Front 54

What is the OAD of KBA?

Back 54

10.2 mm

Front 55

T/F - Prism-ballasted front-surface torics can work with K-cones.

Back 55

False ("Nah!")

Front 56

Why is a bitoric design "tempting" to use with K-cones?

Back 56

Irregular astigmatism thus no particular corneal toricity. Even if periph cornea is toric, bitoric design is more apt to peripheral seal-off.

Front 57

What benefits and problems are assoc w/ large OADs when fitting K-cones?

Back 57

- Benefit = centration not an issue
- Problems = harder to avoid excess areas of clearance and bubbles under OZ; adequate edge clearance more of a challenge

Front 58

When is a large OAD for K-cones indicated?

Back 58

- Decentered cone apex
- Enhance initial comfort

Front 59

T/F - Ortho-K is contraindicated for K-cones.

Back 59

True

Front 60

What is the problem with K-cone SCLs?

Back 60

Tend to be thick therefore poor O2 transmissibility.

Front 61

When is a piggy-back lens indicated for K-cones?

Back 61

For initial comfort, 3-9 staining, or bandage

Front 62

SynergEyes Hybrid Cl is approved for what conditions?

Back 62

- Post-surgical
- K-cones
- Multifocal

Front 63

SynergEyes Hybrid CL (fill-in):
- OAD = ___mm
- Center = ___mm
- Center material = ___
- Center Dk = ___
- ___% water soft skirt

Back 63

14.5 mm OAD
8.2 mm center
Paragon HDS 100 Dk rigid center
30% water soft skirt

Front 64

T/F - Can use piggyback if see 3-9 staining in your K-cone patient.

Back 64

True

Front 65

Name the steps in the Game-Day Game-Plan for K-cones.

Back 65

1) Measure K curvature
2) Select first trial lens BC
3) Eval apical FP
4) Observe pooling under OZ
5) Eval edge lift/PC
6) Sphero-cyl OR

Front 66

Your first trial lens BC in fitting K-cone RGPs should be...

Back 66

somewhere between steep K finding and avg K value (fudge toward steep K)

Front 67

T/F - Bubbles are acceptable in K-cone fits since there is a moderate amount of clearance around the cone.

Back 67

False - want the steepest apical touch lens, but avoid bubbles.

Front 68

You see minimal periph clearance when fitting your K-conus pt with your DxCL; what parameter should be changed in your order and how?

Back 68

Order flatter SCr

Front 69

What SCr is typically suitable for K-cones?

Back 69

8.50 mm (range from 8.00-9.00)

Front 70

You should do a sphero-cyl OR on a K-cone with which of the following trial lenses:
1) Steepest touch
2) Flattest clearance
3) Steepest clearance
4) Flattest touch

Back 70

1) Steepest touch

Front 71

There tends to be a (+/-) TL in K-cone RGP fits?

Back 71

+

Front 72

T/F - In K-cone RGP fits, an increase in BC (in D) typically means a decreased OZ.

Back 72

True

Front 73

T/F - K-conus does not typically affect the mid-peripheral and peripheral corneal topography.

Back 73

True

Front 74

Center thickness in K-cone RGP fits are typically (thinner/same/thicker) vs. normal RGPs. Why?

Back 74

slightly thicker, even though high minus CLP, because of relatively flat periph curve system.

Front 75

Why do a blend in K-cone RGP fits?

Back 75

Makes periph curve system more "aspheric"