Week 1 - Tear Film & its Relation to Cls

Question 1

What are the 3 layers of the tear film? (Inner to outer)

Answer 1

Mucin layer (inner mucus)
Aqueous layer (watery middle)
Lipid layer (outer oily)

Question 2

What is the basic function of the mucin layer?

Answer 2

adheres tear to the eye

Question 3

What is the basic function of the aqueous layer?

Answer 3

nourishes and protects the cornea

Question 4

What is the basic function of the lipid (oil) layer?

Answer 4

lubricates and prevents evaporation

Question 5

Why do we assess the conditions of the tear film? 3

Answer 5

-help determine good cls candidates
-slightly dry eyes negatively impact cls
-aid with selection of appropriate lens design.

Question 6

Dry eye is also known as ………………

Answer 6

Keratoconjunctivitis sicca

Question 7

What are the 10 symptoms of dry eye?

Answer 7

• Soreness
• Tiredness
• Grittiness
• Dryness
• Burning
• Itching
• Photosensitivity
• Foreign body sensation
• Irritation
• Discomfort lid heaviness

Question 8

What is tear osmoloarity?

Answer 8

a measurement used to determine how much salt is in your tears

Question 9

What is hyperosmolarity?

Answer 9

tears have too much salt in them

Question 10

If someone has hyperosmolarity, what can it indicate?

Answer 10

that tears are evaporating too quickly leading to aqueous deficiency

Question 11

What test is done to detect tear osmoloarity?

Answer 11

TearLab

Question 12

How is the TearLab test conducted?

Answer 12

The test device is
touched to the tear lake
in the outer corner of the
eye with the patient
looking up

Question 13

A value greater than 300
mOsm/L is considered
abnormal. T/F

Answer 13

True

Question 14

What does TBUT stand for?

Answer 14

Tear Break Up Time

Question 15

What does TBUT measure?

Answer 15

measures the stability of the tear film to assess for evaporative DED.

Question 16

How does the TBUT test work?

Answer 16

measures the time between the last blink and the first dry spot in the tear film

Question 17

Less than 10 seconds in the TBUT is abnormal. T/F

Answer 17

True

Question 18

What two things do we use when measuring the TBUT? 2

Answer 18

Fluorescein + cobalt blue illumination

Question 19

What are we measuring when considering tear quantity or tear volume?

Answer 19

the amount of tears the patient has

Question 20

The tear prism height is measured using the biomicroscope. T/F

Answer 20

True

Question 21

What height is considered normal when measuring tear prism?

Answer 21

0.20mm - 0.40mm

Question 22

What measurement during the tear prism test does it suggest reduced tear volume?

Answer 22

less than 0.20mm

Question 23

What measurement during the tear break up test is suggests poor drainage?

Answer 23

more than 0.40 mm

Question 24

How does the Schirmer’s test work? 2 steps

Answer 24

-the thick strip of filter paper is placed in both inferior fornices for 5 minutes
-strip is removed and the amount of tear is measured in millimeters

Question 25

What is oxygen transmissibility?

Answer 25

measurement provided by the lab for the movement of oxygen in cls material

Question 26

Oxygen transmissibility is measured in Dk/t.

What does high Dk/t value indicate?

Answer 26

there is more oxygen movement in a lens

Question 27

Oxygen transmissibility is measured in Dk/t.

What does a low Dk/t value indicate?

Answer 27

there is less oxygen movement in a lens

Question 28

In hydrogel contact lenses, the higher
the oxygen transmissibility in a
material the higher the water content.
This does not ring true for Silicone
Hydrogels though.

Question 29

What can we change in the contact lenses to suit someone with dry eyes? 4

Answer 29

-change to a soft highly lubricious lens
-change to a lens that displays minimal eye- dehydration
-replace lenses more frequently
-refit to RGP