Applied Anatomy and Physiology of Eye Flashcards

1
Q

Which type of epithelium forms the cornea?

A

Stratified squamous non-keratinising epithelium

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2
Q

Name the five layers of the cornea seen in histology.

A
  1. Epithelium
  2. Bowman’s membrane (basement membrane for the epithelium)
  3. Stroma
  4. Descemet’s layer
  5. Endothelium
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3
Q

What is the stroma layer composed of?

A

Connective tissue composed of collagen

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4
Q

Which layer of the cornea is the largest?

A

Stroma

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5
Q

Describe the structure of the collagen fibres in the stroma.

A

Uniform diameter and placed equally away from each other, allowing light to go through the cornea

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6
Q

In the stroma, there is the absence of any…?

A

Blood vessels
This is to maintain transparency

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7
Q

Name the basement membrane of the:
1. Corneal epithelium
2. Corneal endothelium

A
  1. Bowman’s membrane
  2. Descemet’s layer
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8
Q

Which is only a single layer of cells- corneal epithelium or endothelium?

A

Corneal endothelium

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9
Q

How many cells are present per squared mm of the corneal endothelium?

A

2500

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10
Q

What is a slit lamp?

A

Microscope which allows you to look at the eye

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11
Q

How is transparency of the cornea maintained?

A

Regular structure of collagen fibres
No blood vessels
Pump of endothelial layer which actively keeps aqueous humor out.

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12
Q

RECAP- what is aqueous humor used to maintain?

A

Intraocular pressure

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13
Q

What happens if endothelial cells are lost in the cornea?

A

The remaining cells enlarge to try and keep the aqueous humor out of the cornea.
Eventually, this fails and fluid leaks into the cornea causing opacification.

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14
Q

Why may a person lose endothelial cells in their cornea?

A

Some degenerative disorders
Surgery such as cataracts as can damage endothelial cells

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15
Q

What is a common complication of cataract surgery?

A

Damage to endothelial cells in cornea causing leakage of fluid, affecting the transparency of the cornea.

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16
Q

What happens to the cornea when there is a healing process of the damage to the endothelial cells?

A

Loss of transparency

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17
Q

Why does the healing process of the eye cause lack of transparency of the cornea?

A

Fibroblasts migrate in and some blood vessels do too. Fibroblasts lay down fibrous tissue, reducing transparency.

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18
Q

What happens to vision when corneal transparency is lost?

A

Vision decreases

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19
Q

What is the treatment for poor vision due to loss of corneal transparency?

A

Corneal transplant

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20
Q

What is an advantage of corneal transplants compared to many other different types of transplant?

A

A direct match is not required like other surgeries. e.g. bone marrow or kidney

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21
Q

Why do recipients of a corneal transplant not need to have the donor’s cornea match up completely?

A

Cornea is avascular- antigens cannot get into the bloodstream and get the body to reject the new cornea.

22
Q

Where is the anterior chamber of the eye?

A

Space between iris and cornea.

23
Q

RECAP- where is aqueous humor produced?

A

Ciliary body

24
Q

Name a structure which helps to drain the angle of the anterior chamber.

A

Trabecular meshwork

25
Q

What would you need to do if you wanted to visualise the trabecular meshwork and other structures of the angle of the anterior chamber of the eye?

A

Use a gonioscope lens.
Without it, the structures cannot be visualised. (the lens helps to eliminate refraction in front of cornea).

26
Q

Why would you want to look at the angle of the anterior chamber?

A

If eye is unable to drain the aqueous humor

27
Q

What would be done if the drainage of the aqueous humor was not treated?

A

Increase in intraocular pressure known as a glaucoma.
Can affect optic nerves on the retina, killing them and resulting in blindness.

28
Q

There are ten layers of the retina…don’t worry, you don’t need to name them all. There are a few that are worth knowing about. Name the outermost layer of the retina.

A

Pigment epithelial layer

29
Q

What does the pigment epithelial layer sit on top of?

A

Choroid

30
Q

What are rods and cones?

A

Modified neurones- light sensitive cells which have photoreceptors.

31
Q

Name the light sensitive layer of the retina.

A

Layer of rods and cones.

32
Q

What supplies inner surfaces of the retina?

A

Branches of the central retinol artery

33
Q

What supplies outer surfaces of the retina?

A

Blood vessels of the choroid

34
Q

In terms of embryology, what does the outer layer of the optic cup give rise to?

A

Pigment epithelium layer of retina.

35
Q

In terms of embryology, what does the inner layer of the optic cup give rise to?

A

All the layers of the retina (except for the pigment epithelium layer).

36
Q

In retinal detachment, describe which layers are detached.

A

The 10th layer is detached from the remaining 9 layers

37
Q

What causes retinol detachment?

A

Fluid fills in space between the two layers of the optic cup.

38
Q

What would you find in the fovea centralis?

A

Cones- this is the point of maximum visual acuity.

39
Q

Why is the fovea the point of maximum visual acuity?

A

-More highly sensitive cones than rods.
-Instead of light needing to travel through eight layers of the retina, the layers at this point are pushed to one side and the layers of cone cells are brought to the surface.

40
Q

What is lens opacification known as?

A

Cataract

41
Q

Why is the lens transparent?

A

Like the cornea, it is avascular

42
Q

What are the functions of the tear film?

A

-Keeps cornea moist
-Washes away foreign bodies
-Has antibodies and lysosomes to kill microbes
-Smooths the outer layer of the cornea producing a smooth site for refraction.

43
Q

What is layer one of the tear film?

A

Mucinous layer

44
Q

What is layer two of the tear film?

A

Aqueous layer

45
Q

What is layer three of the tear film?

A

Oily layer

46
Q

What happens to the fluid in the aqueous layer of the tear film every time we open our eyes?

A

Fluid in aqueous layer starts to evaporate.

47
Q

What is the purpose of the oily layer of the tear film?

A

Slows down the evaporation of fluid from the aqueous layer of the tear film.

48
Q

Which type of dye is used to stain the tear film when looking at the eye?

(orange dye, often used at opticians! Colin uses it for you xox)

A

Fluorescein

49
Q

What happens to the tear film every time you blink?

A

Tear film is distributed more evenly

50
Q
A