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Ocular Anatomy > Lecture 2: 11/10 > Flashcards

Lecture 2: 11/10 Flashcards

1
Q

what is the groove structure between the junction of the cornea and sclera?

A

called a sulcus (external and internal parts)

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2
Q

what is unique about the external sulcus of the cornea?

A

can’t see it because that groove is filled over with conjunctiva

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3
Q

what important structure is in the inside sulcus of the cornea?

A

trabecular meshwork

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4
Q

what is the trabecular meshwork important for?

A

for drainage of the fluid in the anterior portion of the eye

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5
Q

central cornea thickness

A

0.50 - 0.70 mm

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6
Q

peripheral cornea thickness

A

0.74 - 1.10 mm

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7
Q

average thickness of the cornea

A

0.56 mm

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8
Q

anatomical measurement of cornea is

A

direct, postmortem on dead cornea

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9
Q

physiological measurement of the cornea is

A

thickness in living human using ultrasonic device

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10
Q

which thickness measurement is more representative: anatomical or physiological?

A

physiological is better because the cornea is functioning and living, post-mortem the cornea starts to swell

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11
Q

to measure corneal thickness, what device can be used?

A

pachometer

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12
Q

anterior cornea values for horizontal and vertical diameter

A

horizontal: 11.7 mm
vertical: 10.6 mm

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13
Q

posterior cornea values for horizontal and vertical diameter

A

horizontal: 11.7 mm
vertical: 11.7 mm

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14
Q

3 possible reasons for the elliptical shape of the anterior cornea

A
  1. embryology
  2. blinking
  3. eyelids
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15
Q

what is a micro cornea and what can cause it?

A

when cornea is smaller than normal and horizontal diameter is less than 11mm
(result of embryology)

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16
Q

what is a meglocornea and what can cause it?

A

when horizontal diameter is greater than 12.5 mm, most likely the result of congenital glaucoma

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17
Q

congenital glaucoma is

A

when you are born with high intraocular pressure, can be caused by ciliary body and iris blocking off trabecular meshwork

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18
Q

treatment of congenital glaucoma is

A

surgery which can take care of anatomical blockage to open trabecular meshwork and allow drainage

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19
Q

central anterior radius curvature cornea

A

7.8 mm

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20
Q

posterior radius of curvature cornea

A

6.5 mm

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21
Q

edema of the cornea results in

A

changes in the anterior radius of curvature because collagen fibers aren’t elastic enough to give and cornea tends to flatten

22
Q

what is the base of cornea anatomical measurement

A

hypothetical line from one end of the cornea to the other

23
Q

how do you measure the vault of the cornea?

A

take measurement from base of cornea hypothetical line to anterior surface of the cornea

24
Q

vault value for the cornea is

A

2.6mm

25
Q

temperature of the cornea is usually

A

90 degrees

26
Q

why does the cornea have a cooler temperature than the core of the body?

A
  • tear evaporation
  • it is an external surface
  • avascular
27
Q

davson experiment results:

A

corneas in 27C became cloudy, when placed back in 37C, they cleared up again

28
Q

conclusion of the davson experiment

A

turning down the temperature slowed down metabolism and the cornea swelled and took on water, pumps slowed down, but speed back up with temperature increase

29
Q

the dehydrated state of the cornea is called

A

deturgescence

30
Q

describe the process of cornea edema

A

collagen fibers interrupted by the water which disturbs fiber precise arrangement leading to cornea opaqueness from pump slowing

31
Q

3 things that can cause cornea edema

A
  1. oxygen deprivation
  2. trauma
  3. IOP
32
Q

average IOP values

A

15-20 mmHg

33
Q

dilated patients can have increased pressure up to what values?

A

40-50 mmHg

34
Q

2 aspects of the cornea are

A

central (cornea proper) and limbus (transition zone to sclera)

35
Q

list of the 5 layers of the cornea proper, from anterior to posterior

A
  1. anterior epithelium
  2. bowman’s membrane
  3. stroma
  4. descement’s membrane
  5. endothelium
36
Q

width of the limbus transition zone

A

1.5-2.0mm wide

37
Q

purpose of the anterior epithelium

A

to present smooth surface for that refracting element of the eye

38
Q

thickness of the anterior epithelium is

A

5-6 cells thick

39
Q

histology of the anterior epithelium

A
  • wet
  • stratified (3 types of cells in this layer)
  • squamous (anterior surface cells are flat and plate like)
40
Q

list 3 cell types found in anterior epithelium

A
  1. basal cells
  2. wing cells
  3. surface cells
41
Q

describe the anterior epithelium cell type: basal cells and their attachments

A

most interior, attached to basement membrane via hemi-desmosomes (not a strong attachment)

42
Q

why is the basal cell layer important?

A

it is the germinal layer for epithelial cell, highest rate of mitosis in the cornea, cells are formed here and work their way up to the surface

43
Q

wing cells appearance and layer details

A

cells that are starting to flatten out, contain the next 3 layers of cells

44
Q

apex and base of wing cells are

A
  • convex on top surface

- concave on bottom surface

45
Q

purpose of wing cells

A

help ad mass to anterior epithelium

46
Q

surface cells have low many cell layers and what kind of histology

A

1-2 layers

-plate like, squamous, pretty flat and wide

47
Q

surface cells have projections called

A

microplicae

48
Q

on surface cells, what are the microplicae projections useful for?

A

thought to have a base for tears to attach and spread out

49
Q

surface cells are attached via

A

demosomes

a lot stronger

50
Q

whole anterior epithelium of the cornea is how thick?

A

50-100 microns

51
Q

anterior epithelium represents what percentage of the thickness of the cornea?

A

10%

Ocular Anatomy (20 decks)

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