Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cornea & Lens and Cataract > Basics > Flashcards

Basics Flashcards

1
Q

The infant globe is what % of the adult size?

A

80%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How often are cilia replaced? If cut? If pulled out?

A

3-5 months; 2 weeks, within 2 months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Voluntary eyelid closings uses what muscles?

A

Preseptal and orbital eyelid muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Subconscious blinking uses what eyelid muscle?

A

Pretarsal portion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Lymphatics drain the medial aspect of the eyelid where?

A

Submandibular and submental nodes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which layer of the cornea is acellular?

A

Bowman’s layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is the highest endothelial cell density?

A

In the periphery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which part of the Descemet’s membrane grows as we age?

A

The posterior amorphous NON BANDED zone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Radial incisions of the cornea does what?

A

Flattens in BOTH the meridian of the incision and 90 degrees away.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Tangential incisions of the cornea does what?

A

Flattens in the meridian of the incision and steepens 90 degrees away. This is called COUPLING.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

For Radial incisions up to what limit in length does it have an effect until the effect reverses.

A

11-mm DIAMETER

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How deep does a radial incision have to be to have optimum effect.

A

85-90%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is an Axenfeld Loop, where is it located, and where does it branch from?

A

Its an intrascleral loop which forms a visible nodule over the ciliary body and branches from the long posterior ciliary nerves.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Slit illumination helps the examiner visualize what?

A

Opaque lesions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Specular reflection is what type of illumination and is helpful to see what?

A

DIRECT. The posterior corneal surface and the endothelium.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Proximal illumination is what type of illumination and helps to see what?

A

INDIRECT. Highlights opacities against deeper tissue layers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Sclerotic scatter is what type of illumination and what does it help with?

A

INDIRECT. Takes advantage of total internal reflection. Beam shines on the limbus and scatters off the sclera causes a faint glow to the cornea. Helps see epithelial edema and nebulae.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What does fluorescein staining of the cornea do?

A

Detects disruption of intercellular junctions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does rose bengal and lissamine green stain detect?

A

Evaluate abnormal epithelial cells (devitalized that have lost normal mucin surface) and ocular surface changes a/w insufficient tear film protection.

20
Q

Which is more toxic - RB or LG?

A

Rose bengal and likely to induce reflex tearing. It is a photosensitized and has ANTIVIRAL effects.

21
Q

Which has a blood vessel core: Follicules or Papillae?

A

Papillae

22
Q

Which part of the cornea is the thinnest?

A

1.50 m temporal to the geographic center.

23
Q

By what % increase in corneal thickness do u start to see Descement’s folds?

A

10%

24
Q

When does epithelial edema occur when corneal thickness exceeds?

A

0.70mm

25
Q

A CCT greater than what suggest higher risk of corneal edema after CE?

A

650

26
Q

Endothelial cell density lower than what causes corneal edema?

A

500 cells/mm2

27
Q

High IOP causes what type of Tap reading?

A

Artifacutally lowers IOP by goldman tap.

28
Q

What is the average endothelial cell density?

A

2400 cells/mm2 (donor corneas should have at least 2000 cells/mm2)

29
Q

What is the refractive power of the endothelium-aqueous interface?

A

-6D (posterior cornea)

30
Q

How many points are measured on the cornea and what zone?

A

4 points and 2.8 to 4.0 mm zone

31
Q

What is wavefront analysis?

A

It measures higher-order aberrations (irregular astigmatism)

32
Q

What are 2 ways to clean the tonometer tips?

A
  1. Soak in diluted bleach or hydrogen peroxide

2. Clean with isopropyl alcohol after every use.

33
Q

Which interface is responsible for most of the eyes refractive power?

A

AIR-TEAR interface

34
Q

The lens capsule is made out of what type of collagen?

A

Type 4 (all basement membranes are made from type 4 ie Descemets)

35
Q

Type 3 collagen is found where?

A

Stromal wound healing.

36
Q

The sclera is predominantly made up with what type of collagen?

A

Type 1

37
Q

What is the power of the lens?

A

15-20D

38
Q

What is the physical basis for the cornea being transparent?

A

Lattice configuration producing destructive interference.

39
Q

Where does the cornea get glucose from?

A

Aqueous humor

40
Q

Where does the cornea get oxygen from?

A

Tear film

41
Q

Where do stem cells for the cornea arise?

A

Pallisades of Vogt

42
Q

What is it called when cell/tissue takes on a different color from stain?

A

Metachromatic

43
Q

What seems to be differently colored when viewed by emitted vs transmitted light?

A

Dichroism

44
Q

What is having more than one refractive index according to direction of transmitted light?

A

Birefringence

45
Q

How thick is the epithelium?

A

50-60 um thick

Cornea & Lens and Cataract (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions