cornea (introduction) Flashcards
structure of the cornea
from inner to outer
- endothelium
- Descemnt’s membrane
- stroma
- bowman’s membrane
- epithelium
- tear film (three layers)
size of cornea
12mm
why the cornea is transparent?
- Regular Arrangement of Collagen Fibers
- Avascular Nature
- Hydration Control
- Presence of Corneal Endothelium
- 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
the refractive power of the cornea
and the lens
40 diopter
the lense = 20 diopter
instruments used for clinical examination of the cornea
mention 6
1.Slit lamp
2.Keratoscope
3.Corneal topography
4.Keratometry
5.Specular microscope
6.Corneal scrapings and biopsy
Classification of corneal diseases
mention 8
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
types of keratitis
according to position
- Superficial keratitis:
- superficial punctuate keratitis
- corneal ulcer - Deep keratitis
- supporative : corneal abscess
- non supporative
types of non-superative keratitis
- disciform keratitis.
- interstitisl keratitis.
What is superficial punctate keratitis?
characterized by, appear, common in
Superficial punctate keratitis (SPK) is characterized by inflamed epithelial cells that appear unstained as whitish dots. It commonly occurs in viral infections.
What is the differential diagnosis for superficial punctate keratitis (SPK)?
punctate epithelial erosions.
What is the diffetrent between superficial punctate keratitis (SPK) and punctate epithelial erosion (PEE)
three points
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.
what is the predisposing factors for corneal ulcer?
6 factors
- xerosis
- exposure
- loss of sensation
- low resistance
- Epithelial edema
- contact lenses
causes of corneal ulcer
- infective
- viral (HSV, HZV)
- bacterial (many)
- fungal (candida, aspergella)
- parasetic (acanthamoeba) - non infective
- exposure
- neurotrophic
symptoms of corneal ulcer
5 symptoms
- pain
- lacrimation
- photophopia
- blepharospasm
- blurred vision
Signs of corneal ulcer
5 signs
- conjunctival injection (circumcorneal)
- epithelial defect (flourescin stain)
- cellular infiltration around the base
- Hypopyon.
- loss of sensation (viral )