Brainscape's Knowledge GenomeTM

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


See full index

OD2-PPO > Cornea > Flashcards

Cornea Flashcards

1
Q

what is the refacting power of the cornea

A

40D, avg ref power is 60D

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

what are the horiz and vert dimensions of the cornea

A
  1. 6mm vert

11. 6 horiz

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

what is the central thickness and the peripheral thickness

A

central: 0.53mm
peripheral: 0.7 mm

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

what can disruption to the basement membrane lead to

A

recurrent corneal erosisions

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

how many layers are in the epithelium

A

5-7 layers

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

what are the cells in the epi

A

basal columnar cells

wing cells in 2 or 3 rows

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

what are the basal columnar cells attached by to the basement membrane

A

hemidesomosomes

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

what is surface area of the outermost cell increased by

A

microplicae and microvilli to facilitate absorption of mucin

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

does the epi scar from infl? why

A

no bc it can regneerate

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

what is the basement membrane secteted by

A

basal cells

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

how long does the basement membrane take to regenerate

A

6-8 weeks

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

what happens when bowmnas is damaged

A

acelular structure does nto regnerate when damaged, scars when disturbed

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

what is the stroma composed of

A

collagen producing fibroblasts, collagen fibrils, ground substance

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

why do we have extremem transparency of the cornea

A

criss crossing of lamellae in stroma

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

what is the ground substance that occupies the space in btwn the lamellae composed of

A

proteoglycans

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

what is dua’s layer

A

aceullular strong layer in pre-descemet’s cornea

separates last row of keratocytes in most cases

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

what is descemet’s compoased of

A

fine lattice work of collagen fibrils

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

why are the epi, endo, and escemets transparent?

why is the stroma transparent?

A

bc of the uniformity of their refractive indices

stroma: bc of the special arrangement of collagen fibrils

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

what provides sensory innervatino of the cornea

A

ophtlamic division of the trigeminal nerve via the long ciliary nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how does the cornea get its blood supply

A

conj episcleral and sceral vessels around corneoscleral limbus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the source of neo

A

palisades of vogt: contain blood vessels and lymphatics

-denate conj projection into cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what contributes to loss of corneal clarity

A
  1. corneal edema (ep edema, stromal edema)
    - scatters light is hydrated 5% more
  2. scarring
  3. corneal neo
  4. corneal injury
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is medicamentosa

A

medicine in eye causes corneal ep

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what are some causes of ep edema

A
  1. PMMA contact lense
  2. epi defects
  3. swimming
  4. medicamentosa
  5. angle closure glauc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

will ep edema decrease va

A

yes.
significant, PAINFUL
halos around light, foggy vision
spectacle blur w/ hard and gas perm lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

is stromal edema significant

A

only a mild reduction va and mild glare
advanced stromal edema=ep edema
painless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is descemet’s stripping surgery endo keratoplasty (DSAEK)

A

damaged endo cells replaceed by donor cells for stromal edema

  • used if endo is not working
  • only descemets and endo is replaced
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

which layers scar and which do not

A

scar: bowman’s layer and stroma
doesnt: epi, descements, endo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

how to grade scars

A

nebular: faint
macular: translucent
leukoma: opaque

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what are scars a result of

A

insult to the stomral matrix, activating keratocytes cells to gather at the site of insult and synthesize new collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

it the pathology is located to the superficial 50-75 microngs, what to use for treatment of scars?
ant third?

A 
phototherapeutic keratectomy (PTK) 
superficial ant lamella keratoplasty (SALK)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what are the 5 symptoms to think of when evaluating corneal insult

A
  1. pain or discomfort
  2. halos
  3. impairment of va
  4. photophobia
  5. lacrimation
33
Q

why is pain felt in the cornea

A

bc the cornea is richy supplied by sensory nerve endings via first division of trigeminal nerve
-has a subep plexus and stromal plexus

34
Q

why do halos occur

A

due to diffraction of light as a result of ep edema

35
Q

why does impairment of va occur

A

loss of central transparency

increaed tearing causes water ot leak into the wound

36
Q

what is photophobia caused by

A

abnormal strong light induced miosis to an inflamed iris and ciliary spasm

37
Q

what is lacrimation caused by

A

seondary to reflex stimulatin of corneal nerves

-its degree frequently parallels the severity of photophobia

38
Q

when the whole ep is denuded such as in a chemical burn, re-ep occurs from migratino of conj cells from…

A

palisades of vogt’s

39
Q

what is a perforation

A

it means that the cornea has been penetrated all the way through

40
Q

what test can you use to see if there is an abrasion

A

seidel test

  • see if any aq fluid leaking out
  • with positive seidel can see clear aq running through the yellow stain
41
Q

what is the diff btwn ulcer and abrasion

A

ulcer goes beyond bowman’s layer, and surrounded by WBC in the stroma, takes up NaFl and it diffuses into the stroma, lotsa red & purulent dischage, circumlimbal flush *sight threatening condition

abrasion rarely goes beyond bowmans, NaFl stays w/in the wound w/ a small circomescribed halo, usually none or small infiltrate, redness is localized w/ no discharge

infected abrasion can lead to an ulcer

42
Q

what is a corneal ulcer

A

a superficial loss of corneal tissue as a result of infection, infl which leads to nerosis
-affects the ep and stroma

43
Q

what is the ultimate event in ulcer formation

A

enzymatic destruction of the macromolec that make up the collagen of the cornea

44
Q

what does anesthetic do to the cornea

A

slows corneal healing so its easier for the cornea to slough off
-only use it to view cornea if you cannot view it w/o

45
Q

what is debridement

A

removement of damaged dissue

debridement scraping of the ep and basement membrane can improve adhesion after healing

46
Q

when to use anterior stromal puncture

A

if recurrent erosion in same protion of off-axis cornea

47
Q

what to use on patients with recalcitrant recurrent erosions

A 
pthototherapeutic keratectomy (PTK) 
-excimer laser to ant 2-4microns of bowman's membrane
48
Q

how to treat an abrasion

A
  • antibiotic to protect cornea
  • cycloplege w/ any sig abrasion to prevent refelxive iritis
  • pressure patch rare if area greater than 10mm
49
Q

after fb is removed, how to treat

A

like a corneal abrasion

50
Q

what is fleischer’s ring

A

at the base of a cone in keratoconus

51
Q

what is ferry line

A

around a filtering bleb (glauc surgery)

52
Q

what is stocker’s line

A

at the head of a ptergygium

53
Q

what is coat’s ring

A

seen after an iron fb is removed

54
Q

what are the 3 most common corneal dystrophies

A
  1. keratoconus
  2. fuch’s ep-endo dystrophy
  3. ep basement membrane disorders
55
Q

what is munson’s sign

A

lower lid looks convex on down gaze

56
Q

what does a sudden break in descemet’s membrane from keratoconus result from?
how to treat?
when does it resolve?

A

too much stroma edema (corneal hydrops) => aq leaks into stroma

  • edema can inc the size of the cornea 2-3x
  • accompanied by rapid decrease in vision and pain
  • treat w/ cycloplegics and hypertonic sol’n (if breaks into ep) and aq suppressors
  • usualy resolves ina couple month s
57
Q

when is keratoconus classified as mild, moderate, and severe

A

mild K < 48D
moderate K48-54D
severe K > 54D

58
Q

what are the different types of cones

A

nipple small: (6mm, may involve over 70% of the cornea

59
Q

in the us, cornel collagen cross linking is performed how

A

epi off, removing the corneal epi and applying riboflavin drops to the eye, then exposed to uva light which produced reactive oxygen molec which forms chem bonds btwn the corneal collagen fibrils

60
Q

what is fuch’s epi-endo dystrophy

A

the rate of cell loss of functioning endo cells is accelerated
-below 500 cells/ mm^2 the cornea beings to swell and vision is blurred

61
Q

what does fuch’s dystrophy lead to

A

stromal and epi edema

epi edema can produce subep bullae which can cause pain

62
Q

what instruement is used to measure corneal endo cell density

A

specular microscope

63
Q

why is the endo important

A

acts as a barrier to the movement of salt and metabolites into the stroma actively pumping bicarbonate ions out of the stroma and back to the aq humor

64
Q

what is the earliest sign of fuch’s

A

guttata which changes the endo layer which decreases its ability to function as a pump

65
Q

what is the best way to view stroma edema? ep edema?

A

indirect ill to view the stria

ep=scerotic scatter

66
Q

why do fuch’s pt have a higher inciddence of glauc

A

bc whatever causes the problem w/ the endo also tends to cuase probs w/ trab meshwork

67
Q

when does vision become sig affected in fuch’s

A

when ep edema develops

68
Q

what should you not use to lower iop in fuch’s

A

carbonic anhydrase inhibitors bc it may compromise endo further

69
Q

what are the most common corneal dystrophies

A

ep basement membrane dystrophy

aka cogan’s, fingerprint, map-dot

70
Q

what are the findings in ep layer dystrophy caused from

A

problems w /the basement membrane

-thickens and it interferes w/ the anchoring of the ep to the stroma

71
Q

in ep layer dystrophy, the dots are what

A

intraep microcysts that contain nuclear debris, cytoplasmic debris and lipids
-are prob inverted basal cells which continue to proliferate

72
Q

what are fingerprints

how are they best seen

A

basement membrane projecting up and trapping the anteriorly migrating cells

best seen in retro

73
Q

what are map-like changes related to

A

multilaminar thickening of basment membrane w/ extension of the aberrant membrane into overlying ep

74
Q

what are blebs

A

localized mounds of fibrillogranular protein btwn bowman’s layer and the ep basement membrane indenting the basal ep

75
Q

which defects can you see w/ positive staining (ep layer dystrophies)

A

maps, microcysts when they break through

fingerprint is combo neg and pos

76
Q

why do phenothiazines (antipsychotics) leave fine yellow borwn white deposits in interpalpebral deep stroma

A

action related to blockage of dopamine receptors in the CNS

77
Q

what does chrysiasis leave on the cornea

A

yellow deposits in post stroma and descemet’s

-effects reversed when drug is stopped

78
Q

what is the corneal affect in retinoids (acutane

A

fine round sub ep opacities in the central and peripheral cornea

OD2-PPO (8 decks)

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