Contact Lenses Iii Mt 1 - Dr. S's Material

Front 1

Name the top 3 reasons for CL dropouts in order of most to least prevalent.

Back 1

1) Discomfort - 28%
2) Easier to wear SRx/too much hassle - 19%
3) To improve vision/needed bifocals/would have to wear both - 10%

Front 2

T/F - Warpage is a short term corneal sequelae of CL-induced hypoxia in the epithelium.

Back 2

True

Front 3

T/F - Ulceration is a long term corneal sequelae of CL-induced hypoxia in the epithelium.

Back 3

False - short term

Front 4

T/F - Edema is a long term corneal sequelae of CL-induced hypoxia in the epithelium.

Back 4

False - short term

Front 5

T/F - Bullae is a long term corneal sequelae of CL-induced hypoxia in the endothelium.

Back 5

False - in the epithelium

Front 6

T/F - Thinning is a long term corneal sequelae of CL-induced hypoxia in the stroma.

Back 6

True

Front 7

T/F - Striae is a short term corneal sequelae of CL-induced hypoxia in the epithelium.

Back 7

False - short term, in the stroma

Front 8

T/F - Folds are a short term corneal sequelae of CL-induced hypoxia in the endothelium.

Back 8

True

Front 9

T/F - Blebs are a short term corneal sequelae of CL-induced hypoxia in the endothelium.

Back 9

True

Front 10

Reminder: review all short and long term sequelae of each corneal layer on page 1

Back 10

(Just a reminder)

Front 11

Corneal epithelium cells have a (high/low) number of mitochondria.

Back 11

low

Front 12

T/F - The lens has mitochondria.

Back 12

False - the lens has NO mitochondria (transparent tissues have little to none)

Front 13

In RGP wear, ___% turnover of tears. In SCL wear, ___% turnover.

Back 13

10-20%, 1-2%

Front 14

How does the epithelium get its glucose?

Back 14

From the aqueous and from glycogen stores in the epithelium.

Front 15

T/F - The stroma is considered to be metabolically inactive.

Back 15

True - but recent debate indicates otherwise...

Front 16

Where does the endothelium get its oxygen?

Back 16

From the aqueous; role of atmospheric O2 unclear

Front 17

Relative consumption of oxygen:
__% epithelium
__% stroma
__% endothelium

Back 17

40, 39, 21

Front 18

A unit volume of endothelial tissue is __x more active than the same volume of epithelial tissue. What is the ratio of epith:stroma:endoth O2 consumption?

Back 18

5x, 10:1:50

Front 19

What substance causes the increase in osmotic load when the O2 levels in the cornea decrease beyond critical levels?

Back 19

Lactic acid

Front 20

The ability of the cornea to supply O2 depends on:

Back 20

1) O2 avail at the atmospheric surface (in tears)
2) O2 at the aqueous surface
3) Permeability of the tissue to O2 transfer

Front 21

Assuming that the tears are fully saturated w/ atmospheric O2, the O2 tension at the surface of the cornea is ___ mmHg, or ___% O2.

Back 21

155, 21

Front 22

The O2 tension at the surface of the cornea at a high altitude (e.g. Denver) is (higher/lower) than at sea level.

Back 22

lower

Front 23

What is the O2 tension at the aqueous surface estimated to be (in mmHg and %)?

Back 23

55 mmHg, 8% O2

Front 24

What is Flex Wear? Continuous Wear? Extended Wear?

Back 24

FW = wear overnight sometimes
CW = wear 30 days continuously
EW = wear several days at a time

Front 25

What is the O2% of 155 mmHg of tension?

Back 25

155/7.4 = 21%

Front 26

Corneal O2:
Open eye = __ mmHg or __%
Closed eye = __ mmHg or __%

Back 26

Open = 155 mmHg, 21%
Closed = 55 mmHg, 8%

Front 27

Lid closure causes an (incr/decr) in tear and stromal pH?

Back 27

decrease

Front 28

Lid closure causes an (incr/decr) in corneal temp?

Back 28

increase

Front 29

What is the minimum O2 % to avoid corneal edema?

Back 29

10%

Front 30

Holden and Mertz found the critical O2 tension level in a closed eye state with EW to be...

Back 30

18%, but as a compromise the suggested standard was set to 12%.

Front 31

The O2% in which no residual corneal swelling remained during the DW phase (open eye phase) of the EW cycle is...

Back 31

12% (this amount is the minimum needed to return back to baseline, to avoid excess swelling)

Front 32

Permeability = Dk or Dk/t?

Back 32

Dk = permeability
Dk/t = transmissibility
(think T in Dk/t and transmissibility)

Front 33

What is EOP? What is the range of EOP?

Back 33

Equivalent Oxygen Percentage

Range = 0-21% (21% is the full amt of avail atmospheric oxygen)

Front 34

If a CL delivered 7% EOP, it would allow (fraction?) of the O2 available in the atmosphere to reach the cornea.

Back 34

7% / 21% = 1/3

Front 35

Corneal CO2 tension in the aqueous is __ mmHg and __ mmHg at the tear film.

Back 35

55, 0

Front 36

CO2 flux occurs (posteriorly/anteriorly) in the cornea, which causes a potential (incr/decr) in pre-corneal tear pH

Back 36

anteriorly, decr

Front 37

Cellular debris is more likely to be trapped in (RGPs/hydrogels)?

Back 37

hydrogels

Front 38

According to the alteration of corneal environment by CLs slides (pg 1), what causes CLARE?

Back 38

Enzymes released during breakdown of cellular matter builds up under CL and evokes a toxic response.

Front 39

(SCLs/RGPs) serve as better insulators of temperature. What is the significance of this?

Back 39

SCLs - increased temp will increase metabolic activity resulting in higher O2 demands

Front 40

T/F - Oxygen consumption is a long term change of the corneal epithelium.

Back 40

True

Front 41

CL wear causes (decr/incr) aerobic metabolism and (decr/incr) anaerobic metabolism in the epithelium.

Back 41

decr, incr

Front 42

Why are stores of epithelial glycogen reduced during CL wear?

Back 42

Not only due to the depleted epithelial glucose, but as a result of the mild epithelial trauma of CL wear.

Front 43

What happens during the tight junctions between epithelial cells in the short term with CL wear?

Back 43

The tight junctions loosen therefore you can see SPK

Front 44

Epithelial surface microvilli (decr/incr) in the (short/long) term.

Back 44

decr, short

Front 45

Accumulation of fluid occurs where in the epithelium in the short term with CL wear?

Back 45

inter-cellular and intra-cellular spaces

Front 46

Epithelial mitosis decreases __% in the short term due to CL wear.

Back 46

94%

Front 47

Why does the epithelium increase in fragility in the long term for CL wearers?

Back 47

Cell turnover rate is decreased

Front 48

Corneal (thinning/thickening) is observed with EW wearers over the (long/short) term. Returns to baseline after __ month of lens cessation.

Back 48

thinning, long, one

Front 49

Over the long term, a (incr/decr) in epithelial O2 consumption occurs in CL wear. Why?

Back 49

decr; could be due to decr cell numbers and decr cell metabolic activity

Front 50

Microcysts are seen in the epithelium, stroma, or endothelium? What is the hallmark sign?

Back 50

Epithelium. Hallmark sign is reverse illumination with indirect retro due to increased refractive index.

Front 51

What are microcysts?

Back 51

Pockets of disorganized encapsulated cellular material.

Front 52

Microcysts are seen more in (EW/DW) CLs?

Back 52

EW

Front 53

Microcysts are seen as early as __ weeks into EW.

Back 53

8

Front 54

What did Zantos say about Tx microcysts?

Back 54

Less than 50, monitor the patient; more than 50, make the change.

Front 55

What is the microcyst paradox with SiHy SCLs? Why does this occur?

Back 55

You see more microcysts instead of less. SiHy SCLs result in an sudden influx of O2 which increases the metabolic rate, therfore increases cell turnover rate and see more of this encapsulated cellular material.

Front 56

T/F - Microcysts have both positive and negative punctate staining.

Back 56

True - see both small indentations and bumps.

Front 57

Why does it take five weeks to several months for microcysts to resolve?

Back 57

It takes at least five weeks for epithelial cells to turn over.

Front 58

Why is a decreased corneal sensitivity seen with CL wear?

Back 58

Due to a decrease in the neural transmitter acetylcholine due to hypoxia.

Front 59

What is a short term effect of CLs on the stroma - striae or stromal thinning?

Back 59

Striae

Front 60

T/F - A hypoxic stroma causes edema.

Back 60

False - edema in the STROMA is caused by osmotic pressure changes due to compromised barriers i.e. the endothelium and/or epithelium.

Front 61

Which has a greater capacity to swell - the posterior or anterior stroma?

Back 61

Posterior - this probably accounts for the appearance of striae in the posterior cornea

Front 62

What are striae?

Back 62

Found in hypoxia but due to the swelling effect. Fine, white, vertically oriented lines, can be observed w/ direct or indirect illum. Thought to be fluid separation of predominantly vertically arranged collagen in post stroma.

Front 63

Describe stromal edema changes:
Safe = __%
Appearance of striae = __%
Appearance of folds = __%
Pathological = __%
Loss of transparency/vision = __%

Back 63

0-5%
5-10%
10-15%
15-20%
<20%

Front 64

What are corneal folds?

Back 64

Dark, deep looking grooves visible in endothelial mosaic, best seen w/ specular reflection. Thought to be physical buckling of posterior stromal layers.

Front 65

Describe the thickness changes that occur in CL wear over time.

Back 65

Initially, cornea swells esp w/ EW. After first week, reaches peak then goes back to baseline and in many cases goes thinner than baseline.

Front 66

What is the mechanism of stromal thinning?

Back 66

Evidence shows that chronic edema alters the fxn of keratocytes so that they produce less stromal tissue.

Front 67

Where are CL-related infiltrates usually found? What are the causes?

Back 67

Sub-epithelial. Due to bacteria, viruses, endotoxins, preservatives, toxicity due to trapped debris under CLs

Front 68

What are blebs?

Back 68

Swelling of endothelial cells immediately after CL application, appearing as dark lines and spots usually last 15-40 min after applying CL. Can be induced with or without hypoxia; perhaps due to pH change or other metabolic by-products.

Front 69

T/F - Endothelial cell shape and size constancy can be lost in CL wear.

Back 69

True

Front 70

What is polymegathism?

Back 70

Variation in endothelial cell SIZE.

Front 71

What is pleomorphism?

Back 71

Variation in endothelial cell SHAPE.

Front 72

What are the effects of higher polymegathism?

Back 72

Greater levels of corneal swelling and slower deswell following hypoxic stress.

Front 73

What is bedewing?

Back 73

A cluster of fluid droplets or a constellation of leukocytes deposited on the surface of the endothelium. Assoc w/ chronic intolerance to CL wear and active inflam of the ant seg.

Front 74

Your CL patient complains of itchiness, and you see increased mucous secretion with papillae on the upper tarsal conj. You suspect...

Back 74

GPC

Front 75

RGPs typically create GPC on zone __ and SCLs usually zone ___.

Back 75

Zone 3 (palpebral conj near lid margin), zone 1 and 2

Front 76

How would you grade this CLIPH?
Symp = mild itching, incr mucous in AM
Sx = none or slight hyperemia

Back 76

Grade 1

Front 77

How would you grade this CLIPH?
Symp = itching, incr mucous in AM, lens awareness and blurred VA late in day
Sx = enlarged papillae w/ mucous over them, slight to mod upper lid hyperemia, mild coating of CL, rare SPK superiorly

Back 77

Grade 2

Front 78

How would you grade this CLIPH?
Symp = mod to severe itch esp upon CL removal, mod-sev mucous, incr CL awarenesss, mod blur VA, decentered CL
Sx = enlarged papillae (>1mm, tips may stain) w/ heavy mucous over them, hyperemic & edematous upper lid, possible sup SPK

Back 78

Grade 3

Front 79

How would you grade this CLIPH?
Symp = severe itch & mucous (lids shut in AM), reduction or D/C CL wear, mod blur VA, decentered CL
Sx = giant papillae (>1mm) w/ heavy mucous over them, edematous & hyperemic upper lid, severe CL coating, may have SPK and/or inflitrates

Back 79

Grade 4

Front 80

T/F - Topical antihistamines can be used to Tx CLIPH.

Back 80

True

Front 81

T/F - Topical steroids can be used to Tx CLIPH.

Back 81

True

Front 82

T/F - 3-9 staining can involve inadequate spread of mucin.

Back 82

True

Front 83

T/F - Both excessive or inadequate edge lift can cause 3-9 staining.

Back 83

True

Front 84

What is the cause of VLK?

Back 84

Staged response or product of PCDS secondary to RGPs

Front 85

A (large/small) diameter RGP with (low/high) edge lift can cause VLK.

Back 85

large, low

Front 86

What are the signs/Sx of VLK?

Back 86

Can be asympt or complain of slight irritation in the area of VLK; inflammation, invasive vascularization

Front 87

What is the management of VLK?

Back 87

It is reversible and non-scarring; Tx includes smaller CL diameter, flatter and wider PCs, ocular lubricants, decongestants, NSAIDs, or steroids

Front 88

To Tx VLK, you can use a (smaller/larger) RGP diameter and/or a (flatter/steeper), (narrower/wider) periph curve.

Back 88

smaller, flatter, wider

Front 89

T/F - Corneal vascularization or neovascularization often involves a symptomatic patient.

Back 89

False - often asymptomatic.

Front 90

Grade __ neovascularization is characterized by <1.5 mm in one quadrant

Back 90

1

Front 91

Grade __ neovascularization is characterized by <1.5 mm in more than one quadrant

Back 91

2

Front 92

Grade __ neovascularization is characterized by 1.5 to <3.0 mm in any quadrant

Back 92

3

Front 93

Grade __ neovascularization is characterized by >3.0 mm in any quadrant

Back 93

4

Front 94

T/F - You can manage neovascularization by increasing lens thickness.

Back 94

False - decrease thickness (to incr O2?)

Front 95

T/F - Microcysts are typically asymptomatic.

Back 95

True

Front 96

Microcysts are caused by...

Back 96

Trapped debris under CL, disorganized cell growth, prolonged hypoxia

Front 97

Microcysts have an onset of __ months and disappear in __ months.

Back 97

2-6 months
1-3 months

Front 98

You see >50 coalesced microcysts - how would you grade this?

Back 98

Grade 3

Front 99

You see more than 50 microcysts in your patient - should you go on with treatment?

Back 99

Yes - decrease CL thickness, increase Dk, reduce WT. If unable to reduce number, refit to DW.

Front 100

Mucin balls are most associated with what type of CL?

Back 100

Silicone Hydrogels

Front 101

You see mucin balls with (steeper/flatter) corneas.

Back 101

steeper

Front 102

T/F - Mucin balls do not leave staining.

Back 102

False - see dimple veiling-like staining pattern after removal of lens.

Front 103

Tx mucin balls with (steeper/flatter) CLs.

Back 103

steeper

Front 104

CLARE often involves uniocular or bi-ocular pain?

Back 104

Uniocular

Front 105

CLARE is a (ulcerative/non-ulcerative), (sterile/non-sterile) keratitis?

Back 105

ulcerative, sterile

Front 106

What organism is involved with CLARE?

Back 106

Gram negative, primarily Pseudomonas but also Serratia marcesens and H. flu

Front 107

T/F - CLARE can be recurrent.

Back 107

True - in SiHy CL wearers

Front 108

T/F - CLARE persists after d/c of CL wear.

Back 108

False - subsides with removal of CLs.

Front 109

Can you Tx CLARE with ABs?

Back 109

Yes, for 48+ hrs with f/u and re-evaluation

Front 110

What specific conditions can you see striae in?

Back 110

Age, DM, keratoconus

Front 111

How do you Tx striae if you see severe edema, ECF, or microcystic edema?

Back 111

Hypertonics or steroid gtts may be indicated.

Front 112

How do you manage corneal infiltrates due to CL wear?

Back 112

CL deprivation, change solns, R/O corneal ulcer

Front 113

CLPU = unilateral or bilateral?

Back 113

Unilateral

Front 114

What is the etiology of CLPU?

Back 114

Colonization of bacteria (G+ incl S. aureus and epidermidis) on lens surface, more on EW vs DW.

Front 115

What does CLPU look like, and where is it localized?

Back 115

Whitish gray focal anterior stromal infiltrate, 0.1-2.0 mm, in the periphery or mid-periphery

Front 116

CLPU involves the resurfacing of epithelium over the lesion, leaving a scar with a (well/ill) defined border.

Back 116

well-defined

Front 117

Compare CLPU Sx vs MK Sx.

Back 117

CLPU = may be absent or moderate (FB, tearing, redness)
MK = symptomatic, may or may not have discharge

Front 118

What is the Tx regimen for MK?

Back 118

Broad spec ABs (fluoroquin.):
2 gtt q15 min for 6 hrs
2 gtt q30 min for 18 hrs
2 gtt q1 hr for 24 hrs
2 gtt QID for 12 days

Front 119

How can you Tx SEALs?

Back 119

Refit w/ diff lens design, water content, or material

Front 120

What causes corneal wrinkling?

Back 120

Mechanical forces on cornea by the weight of the lid and lens; seen in thick RGP lenses, or mid-water content, thin HEMA soft lenses

Front 121

Tx corneal wrinkling?

Back 121

Refit or D/C CL wear

Front 122

What causes polymegathism? Is it reversible?

Back 122

Prolonged hypoxia; not reversible.

Front 123

What typically causes arcuate staining (smiley face)?

Back 123

Tight lens

Front 124

T/F - SLK can involve superior staining.

Back 124

True

Front 125

T/F - Blepharitis only invovlves inferior staining.

Back 125

False - can be inferior and/or superior staining

Front 126

You see a band-shaped SPK pattern - what do you suspect?

Back 126

nasal/temporal pinguecula

Front 127

Review vascular responses to CL wear?

Back 127

(Just a reminder)

Front 128

Compare corneal wrinkles vs. corneal folds.

Back 128

Folds = endothelial, a buckling of posterior stromal layers
Wrinkles = epithelial, due to mechanical forces on cornea by weight of lid and lens (e.g. thick RGPs or mid-H2O, thin HEMA SCL)