Cornea, Conjunctiva, And Refractive Surgery

Front 1

What are the 2 layers of the conjunctiva?

Back 1

Epithelium and Lamina propria

Front 2

What innervates the conjunctiva?

Back 2

CN V

Front 3

The conjunctiva is parasympathetically innvervated by

Back 3

Long ciliary nerves

Front 4

What are the 5 layers of the cornea?

Back 4

Epithelium, Bowman's, Stroma, Decemet's, Endothelium

Front 5

How thick is corneal epithelium?

Back 5

50 microns

Front 6

What 2 things is the corneal stroma made up of?

Back 6

Lamellae and cells

Front 7

What angle are stromal lamallae oriented with respect to each other?

Back 7

60 degrees

Front 8

Can Descemet's regenerate?

Back 8

Yes

Front 9

How does Descemet's change with age?

Back 9

It gets thicker.

Front 10

What are Hassall Henle bodies?

Back 10

Localized thickenings of Descemet's in the peripheral cornea due to age.

Front 11

Where is nerve density the greatest in the cornea?

Back 11

Central 5 mm

Front 12

Name the parts of the cornea that are innervated

Back 12

Epithelium, Bowman's and Stroma

Front 13

How is the cornea innervated?

Back 13

CNV, long posterior ciliaries

Front 14

The cornea regenerates how often?

Back 14

Every 7 days

Front 15

Conjunctiva is formed from what?

Back 15

Surface ectoderm

Front 16

Glands of Zeiss and Moll are actually

Back 16

epithelial ingrowths

Front 17

What is the primary inductive mechanism for corneal differentiation?

Back 17

Growth and development of the optic cup.

The cornea will not form if the optic cup is missing.

Front 18

Name the mesenchymal components of the cornea

Back 18

Bowman's, stroma, Decemet's, and endothelium

Front 19

What forms the corneal epithelium?

Back 19

Surface ectoderm

Front 20

What is average cornea size at birth?

Back 20

10 mm

Front 21

At what age does the cornea reach adult size?

Back 21

2 years

Front 22

What is adult corneal size?

Back 22

12 mm

Front 23

At birth, corneal curvature is (steeper/flatter) than adults.

Back 23

Flatter

Front 24

What is the water content of the cornea?

Back 24

78%

Front 25

What is the water content of the stroma?

Back 25

75-80%

Front 26

What is responsible for the high water content of the stroma?

Back 26

Mucopolysaccarides (MPS)

They are hydrophilic.

Front 27

What is the main source of energy for corneal epithelial cells?

Back 27

Glucose and Glycogen

Front 28

The Kreb's cycle produces ________ which causes the cornea to _____.

Back 28

Lactic acid, swell

Front 29

What structures consume most of corneal O2?

Back 29

Epithelium and Endothelium

Front 30

What is glutathione?

Back 30

A chemical important in endothelial function. It eliminates free radicals and toxins formed during light exposure.

Front 31

Epithelial cells secrete ________ into the tears to maintain hypertonicity.

Back 31

Chloride

Front 32

At what oxygen tension does the cornea begin to swell?

Back 32

10-20 mmHg

Front 33

What is the partial pressure of O2 with the eyes open? Eyes closed?

Back 33

155 mmHg, 55mmHg

Front 34

Where does the epithelium get it's O2?

Back 34

Aqueous

Front 35

The cornea is extremely sensitive to ________ but not to ________.

Back 35

Cold, heat

Front 36

Describe EBMD

Back 36

AD, pain upon awakening, recurrent epithelial erosions, negative flourescein staining, negative Bell's phenomenon.

Front 37

Describe Cogan's microcystic epithelial dystrophy

Back 37

More common in females. Grey, white, round, or comma shaped deposits in the epithelium. The deposits are cysts due to remalforming epithelial cells.

Front 38

What causes Map Dot Fingerprint Dystrophy

Back 38

Bowman's layer grows over corneal epithelial basal cells.

Front 39

Describe Reis Buckler's dystrophy

Back 39

Bowman's layer dystrophy.
"Fishnet" or "honeycomb" appearance due to destruction and scarring of Bowman's layer.
Corneal erosions and decreased corneal sensation.

Front 40

Where is vortex dystrophy located?

Back 40

Between Bowman's and the stroma.

Front 41

What is vortex dystrophy associated with?

Back 41

Fabry's disease or pharmacological agents such as amiodarone and tamoxifen.

Front 42

Name two anterior stromal dystrophies

Back 42

Granular dystrophy and lattice dystrophy

Front 43

Lattice dystrophy is from the accumulation of _________.

Back 43

amyloid

Front 44

Describe macular dystrophy

Back 44

AR, full stromal thickness
Central, grey white, opacities consisting of glucosaminoglycan. Accumulation of mucopolysaccharides. Can extend into the periphery.

Front 45

What is the treatment for Fuch's dystrophy?

Back 45

Initially hypertonic drops and bandage CL. Then penetrating keratoplasty.

Front 46

What are dellen?

Back 46

Focal, peripheral corneal thinning close to limbus, seen at 3 and 9 o'clock.

Front 47

Ferric ions around a surgical bleb are called ...

Back 47

Ferry's line

Front 48

Patient presents with a complete of severe itching all year with moderate to severe SPK.

Back 48

atopic keratoconjunctivitis

Treat with cold packs and Pred

Front 49

Describe marginal keratitis

Back 49

Corneal lesions caused by an infiltrative response to staph extotoxins. Clear margin between lesion and limbus.

Treat with Gentamicin, Bacitratin, and maybe cycloplege.

Front 50

Describe phlyctenular keratoconjunctivis

Back 50

Like marginal keratitis, only no clear zone between limbus and lesion. Instead see "leash" of vessels.

Treat with Pred or Dexamethasone

Front 51

What is the most common bacterial ulcer?

Back 51

Pseudomonas

Front 52

Describe a streptococcus ulcer

Back 52

Centrally located, fuzzy borders, can enter an intact epithelium

Front 53

Name 2 gram negative organisms that can enter an intact epithelium

Back 53

Pseudomonas and Neisseria

Front 54

What are the EKC rules of 8?

Back 54

Adenovirus 8
First 8 days have conjunctivitis and very contagious
Eight days later SPK
Eight days later subepithelial infiltrates.

Front 55

Describe stromal infiltrative keratitis

Back 55

Necrotic, blotchy, cheesy white infiltrates in stroma. Classic signs are infiltration, neovascularization, and stromal thinning.

Refer to corneal specialist.

Front 56

In chlamydia, a patient will have both _______ and ________ signs.

Back 56

Viral and bacterial

Front 57

How do you treat ocular chlamydia?

Back 57

Oral tetracycline in adults,
Sulfa or erythromycin in babies.

Front 58

90% of all interstitial keratitis is due to what?

Back 58

Syph

Front 59

What is trachoma?

Back 59

Similar to chlamydia. Found in underdeveloped countries with UTI. Treat with tetracycline.

Front 60

Describe vernal keratoconjunctivits.

Back 60

Seasonal allergy. Papillae, Tranta's dots, ropey mucus. Treat with steroids.

Front 61

What is the mechanism of action for topical anesthetics?

Back 61

They compete for Ca channels and block them. They directly inhibit the permeability of the nerve to sodium.

Front 62

What is the mechanism of action of a steroid?

Back 62

The steroid enters the cell and bind to receptors in the cytoplasm. It is transported to the nucleus where it regulates the formation of mRNA.

Front 63

What is the mechanism of action of a NSAID?

Back 63

NSAIDs block cyclooxgenase, which converts arachadonic acid into the precursors for prostaglandins and thromboxane.