Slit Lamp Bio-microscopy from contact Lenses -CSB

Question 1

What does it mean to be therapeutic?

Answer 1

Relating to the healing of disease.

Question 2

What is Aphakia?

Answer 2

Aphakia is the absence of the crystalline lens of the eye

Question 3

For myopes is visual acuity improved or decreased when comparing contacts to glasses?

Answer 3

Contact lenses provide a higher visual acuity for myopes than glasses

Question 4

Why may acuity be decreased (when compared to glasses) for hyperopes when contact lenses are worn?

Answer 4

There is a possibility that the decreased acuity is due to decreased magnification and fluctuating accommodation.

Question 5

How are slit lamps used in regards to Contact Lens Prescribing?

Answer 5

They are used in a contact lens fitting for baseline measurements and aftercare to check for lens fit, surface condition and ocular integrity.

Question 6

What are concretions?

Answer 6

Little vacuoles or cysts filled with lipid

Question 7

What are high, low and medium magnifications on a slit lamp used to look at in regards to the eye?

Answer 7

– Low 6-10x for general eye – Medium 16x for structures – High 25-40x for detail

Question 8

What would low magnification on a slit lamp be used to look for?

Answer 8

• Lids/lashes • Cornea • Conjunctiva • Sclera

Question 9

What would medium magnification on a slit lamp be used to look for in regards to Contact Lens Prescribing?

Answer 9

-Blepharitis • Meibomian gland dysfunction • Concretions • Corneal staining

Question 10

What would medium magnification on a slit lamp be used to look for in regards to Contact Lens Prescribing?

Answer 10

-Epithelial changes • Stromal striae and folds • Endothelial folds, blebs, and polymegethism

Question 11

What is your responsibility if you find any sign of corneal hypoxia in a contact lens patient?

Answer 11

Take the contact lens out. Not allow the patient to wear any lenses until the problem goes away and teach the patient about proper contact lens care.

Question 12

What are Stromal Striae?

Answer 12

Fine grayish white lines in the corneal stroma. These represent localized separations of the highly ordered collagen

Question 13

What are Stromal Folds?

Answer 13

More advanced striae where fluids have caused localized undulations (up and down outlines) or wrinkles in the cornea.

Question 14

What do Stromal Striae lead to?

Answer 14

Stromal Folds

Question 15

When are Stromal Striae or Folds present?

Answer 15

When corneal oedema is occuring.

Question 16

What effect do corneal Straie or folds have?

Answer 16

They cause a loss of vision. (milky cornea).

Question 17

What does the cobalt blue filter on a slit lamp do?

Answer 17

Excites Fluorescin

Question 18

What does the green (red-free) filter do on a slit lamp?

Answer 18

Enhances contrast of blood vessels and rose bengal staining

Question 19

What does the ground glass filter on a slit lamp do?

Answer 19

Diffuses beam to give broad unfocussed illumination

Question 20

What does a neutral density filter on a slit lamp do?

Answer 20

Reduces beam brightness, increases patient comfort

Question 21

What does a polarising filter on a slit lamp do?

Answer 21

Reduces specular reflections when used in crossed pairs

Question 22

What is fluorescein staining used for in slit lamp?

Answer 22

It highlights epithelial defects as it stains areas of missing cells.

Question 23

How long does it take the fluorescein dye to disapear?

Answer 23

2-4 minutes.

Question 24

What filter/filters in slit lamp do we use in conjunction with fluorescin staining?

Answer 24

Cobal blue Filter however we may also use a Yellow (Wratten 12) filter to improve contrast.

(When a wratten 12 filter is used then you are looking out for green and everything that was previously blue is now black- essentially its like putting a yellow filter over a blue filter).

Question 25

Do we add fluorescein to an eye that's wearing a soft contact lenses?

Answer 25

No because fluorescein stains everything including the lens. The only time we would do this is if we are trying to check for the presence of a contact lens.

Question 26

What is lissamine green stain used for?

Answer 26

Lissamine green is used in dry eye examinations . It stains dead and degenerative cells, but not healthy epithelial cells

Question 27

What slit lamp filter is lissamine green used in conjunction with?

Answer 27

Red (Wratten 25) filter is used to enhance staining

Question 28

When does optimum staining for lissamine green occur?

Answer 28

1-4 minutes

Question 29

Does lissamine green stain cause discomfort for the patient?

Answer 29

A little

Question 30

Which stain is more tolerable, Lissamine green or Rose Bengal (RB)?

Answer 30

Lissamine green

Question 31

Is rose bengal stain uncomfortable for pateints?

Answer 31

Yes - It Stings!

Question 32

What is Rose Bengal Stain and what does it do?

Answer 32

A fluorescein derivate that is able to bind to epithelial cells that are uncoated by certain proteins (mainly mucin). It stains dead cells and healthy ones that are unprotected by an intact mucin layer

Question 33

What are microcysts and why are they an important thing to look out for in regards to contact lens checking?

Answer 33

A tiny lesion filled with dead cell material. They are very distinct and a definite indicator of contact lens induced hypoxia.

Question 34

How can retro-illumination on slit lamp be used to identify vacuoles and microcysts?

Answer 34

Essentially both microcysts and vacuoles are spaces in the epithelium that are filled with either a gas or fluid. This means that the light that comes back from a point that you have illuminated is defracting/diverging or refracting/converging. Whether the light hitting you back diverges or converges depends on what the space is filled with ( either gas or fluid -i.e. whether its a vacuole or microcyst). What you would see in this case is like small circles that are half light and half black depending on where shadow has been created. - see picture attached.

Question 35

What are vacuoles in the eye?

Answer 35

Cyst like inclusions (something embeded) which is filled with gas or fluid

Question 36

Where do microcysts and vacuoles exist if they are present?

Answer 36

In the corneal epithelium

Question 37

How can you diffrentiate between a microcyst and a vacuole using a slit lamp ( and retroillumination)?

Answer 37

So if the circle that you suspect to either be a vacuole or microcyst indication has a shadow on the same side as ur beam of light then its a microcyst. If the shadow is on the opposite side to the side where the beam of light exists then its a vacuole.

Question 38

Why would there be a smile line staining pattern during corneal staining?

Answer 38

The patient doesn't blink fully - the bottom part of their lensdries out - often from staring at computer

Question 39

What contact lens patients may have dessication 3 & 9 staining ? (3 and 9 refer to location on a clock)

Answer 39

Rigid Hard Contact Lenses (RGP) lenses

Question 40

When may toxicity diffuse staining be seen?

Answer 40

By a patient that has an allergic reaction to the contact lens.

Question 41

What are the different types of corneal Staining patterns?

Answer 41