Overnight Wear (M2)

Question 1

What is the timing of wearing CLs to be considered extended wear? 1. Continuous wear? 2

Answer 1

1. 1 to 6 nights of overnight wear

2. 30 days of overnight wear

Question 2

What are the benefits of overnight wear CLs?

Answer 2

1. infrequent application and removal
2. good vision at all times
3. reduces cost associated with lens care

Question 3

What was thought to be the primary culprit of microbial keratitis, but was found to be false after SiHy technology saw no dec in prevalence?

Answer 3

hypoxia

Question 4

What is the Holden Mertz criteria Dk/t value to avoid excess overnight edema and limbal hyperemia?

Answer 4

125

Question 5

What is the Holden Mertz criteria Dk/t value that can lead to lid and lens edema that is recoverable during eye wear time?

Answer 5

87

Question 6

What is the Holden Mertz criteria Dk/t value to avoid end of seventh day edema?

Answer 6

35

Question 7

What is the Holden Mertz criteria Dk/t value that leads to none to trace end of first day edema and is the daily wear criteria?

Answer 7

24

Question 8

What happens to the Dk of a hydrogel lens with increased water content? 1. Silicone hydrogel lens? 2

Answer 8

1. increases Dk

2. decreases DK until about 70% water content and then increases

Question 9

Do males or females wear their CLs overnight more often?

Answer 9

males

Question 10

Which GP lenses can be used for extended wear?

Answer 10

1. Menicon Z
2. Boston XO2
3. CRT

Question 11

What is the follow up schedule for an extended wear patient?

Answer 11

1 day, 1 wk, 1 month, 3 months, 1 yr

Question 12

What should be done at the initial fit for extended wear patients?

Answer 12

1. educate patient on risks and benefits

2. sign informed consent?

Question 13

What are the conditions that occur when the lids are closed?

Answer 13

1. hypoxia
2. dec tear exchange
3. inc CO2
4. acidic pH
5. inc in bacterial colonization

Question 14

What are the possible impacts of CLs on the endothelium?

Answer 14

1. polymorphism (diff sizes)

2. pleomorphism (diff shapes)

Question 15

What are the impacts of CLs on the epithelium?

Answer 15

1. thinner epithelium
2. dec rate of exfoliation
3. dec stem cell turnover if low Dk

Question 16

What are the dots on the corneal midperiphery and periphery that indicate hypoxic stress? 1. Do these have reversed or non reversed illumination?

Answer 16

1. epithelial microcysts

2. reversed illumination

Question 17

How does switching to SiHy lenses impact the amount of microcysts present?

Answer 17

increases with a spike at first then decreases overall

Question 18

How much vascularization is considered to be significant? 1. What materials lead to this? 2

Answer 18

1. 1mm or more

2. lower Dk materials

Question 19

What appears in the cornea with 5% edema? 1. With 10%? 2. With 15%? 3. What is the normal percent amount of edema from overnight wear? 4

Answer 19

1. loss of transparency
2. folds appear
3. striae appear
4. 3 to 4%

Question 20

What is the possible impact of low Dk/t (SiHys and hydrogels may too though) on the stroma?

Answer 20

dec keratocyte density

Question 21

What is the possible impact of low Dk on refractive error?

Answer 21

half saw -0.25 to -0.50 myopic shift

Question 22

What is a side effect of SiHy lenses that leads to dots on the cornea?

Answer 22

mucin balls

Question 23

What is the percentage of symptomatic patients for extended wear SiHys?

Answer 23

2.5 to 6%

Question 24

How does the risk of MK compare for ortho-K, daily wear GP, and soft lenses?

Answer 24

highest to lowest risk: soft lenses, ortho-K, DW GP