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Opthalmology > Cornea (introduction) > Flashcards

Cornea (introduction) Flashcards

1
Q

structure of the cornea

from inner to outer

A
  1. endothelium
  2. Descemnt’s membrane
  3. stroma
  4. bowman’s membrane
  5. epithelium
  6. tear film (three layers)
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2
Q

size of cornea

A

12mm

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3
Q

why the cornea is transparent?

A
  1. Regular Arrangement of Collagen Fibers
  2. Avascular Nature
  3. Hydration Control
  4. Presence of Corneal Endothelium
  5. Uniform Cellular Structure

if you know another better answer, let me know. It is not an answer but little notes
The cornea must be little dehydrated (corneal deturgescence)
Epithelium is non keratinized
There are no blood vessels, lymph vessels, and no myeline

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4
Q

the refractive power of the cornea

and the lens

A

40 diopter

the lense = 20 diopter

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5
Q

instruments used for clinical examination of the cornea

mention 6

A

1.Slit lamp
2.Keratoscope
3.Corneal topography
4.Keratometry
5.Specular microscope
6.Corneal scrapings and biopsy

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6
Q

Classification of corneal diseases

mention 8

A

1.Infections and inflammations (keratitis)
2.Corneal ectasia (keratoconus)
3.Corneal degenerations
4.Corneal deposits
5.Exposure keratopathy
6.Neurotrophic keratopathy
7.Nutritional deficiency
8.Physical injury

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7
Q

types of keratitis

according to posiposition

A
  1. Superficial keratitis:
    - superficial punctuate keratitis
    - corneal ulcer
  2. Deep keratitis
    - supporative : corneal abscess
    - non supporative
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8
Q

types of non-superative keratitis

A
  1. disciform keratitis.
  2. interstitisl keratitis.
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9
Q

What is superficial punctate keratitis?

characterized by, appear, common in

A

Superficial punctate keratitis (SPK) is characterized by inflamed epithelial cells that appear unstained as whitish dots. It commonly occurs in viral infections.

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10
Q

What is the differential diagnosis for superficial punctate keratitis (SPK)?

A

punctate epithelial erosions.

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11
Q

What is the diffetrent between superficial punctate keratitis (SPK) and punctate epithelial erosion (PEE)

three points

A

SPE
1. vissible without stainig.
2. associated with inflammation.
3. due to viral infection
PEE
1. require staining to be identified
2. not assotiated with inflammation.
3. occure in many conditions.

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12
Q

what is the predisposing factors for corneal ulcer?

6 factors

A
  1. xerosis
  2. exposure
  3. loss of sensation
  4. low resistance
  5. Epithelial edema
  6. contact lenses
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13
Q

causes of corneal ulcer

A
  1. infective
    - viral (HSV, HZV)
    - bacterial (many)
    - fungal (candida, aspergella)
    - parasetic (acanthamoeba)
  2. non infective
    - exposure
    - neurotrophic
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14
Q

symptoms of corneal ulcer

5 symptoms

A
  • pain
  • lacrimation
  • photophopia
  • blepharospasm
  • blurred vision
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15
Q

Signs of corneal ulcer

5 signs

A
  1. conjunctival injection (circumcorneal)
  2. epithelial defect (flourescin stain)
  3. cellular infiltration around the base
  4. Hypopyon.
  5. loss of sensation (viral )
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16
Q

what is hypopyon

A

pus like (sterile WBCs collection) in the anterior champer of the eye

17
Q

the earlies signs of eye prforation

mention 3

A
  1. eccentric oval pupil.
  2. shallow anterior champer
  3. hypotony
18
Q

what is the meaning of Disciform keratitis?

A

disc-shaped lesions in the corneal epithelium

19
Q

cause of Disciform keratitis

A

HSV

20
Q

Complications of corneal ulcer

6 complications

A
  1. Corneal opacity
  2. Iridocyclitis
  3. Secondary glaucoma
  4. Thinning with development of descmatocele
  5. Corneal vascularisation
  6. Corneal perforation
21
Q

Treatment of corneal ulcers

A
  1. Local and systemic antibiotics
  2. cycloplegia
  3. patching with eye pad
  4. therapeutic contact lenses
  5. tarsoraphy
22
Q

characterized by small, round, and shallow indentations at the corneal margin

what is it and indicate for what?

A

Herbert’s pits (trachoma)

23
Q

Small, white, round lesions located at the limbus of the cornea, commonly associated with allergic conjunctivitis

what is it and indicate for what?

A

Tranta’s dots (Vernal keratoconjunctivitis)

24
Q

V-shaped indentation observed in the lower eyelid when the patient’s gaze is directed downwards

what is it and indicate for what?

A

munson sign (keratoconus)

25
Q

uses of contact lenses

A

Visual
- cosmotic
- anisometropia
- high ametropia
- astigmatism
Therapeutic
- impending perforation
- epithelial protection

Opthalmology (20 decks)

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