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opthalmology by sayeed > Cornea > Flashcards

Cornea Flashcards

1
Q

Layers of cornea

A

1 epithelial - 5-6 layers
2 bowman’s layer-condensed collagen fibers
- can’t regenerate if destroyed so heals by scarring
3 stroma-contains type 1 & 5 collagen fibrils intervened by type 4 fibers
-fibers are embedded in hydrated proteoglycans
-Wandering macrophages,histocytes & few leukocyte are present
4 descement membrane-contains collagen and glycoproteins
-it can regenerate
- it is very resistant to trauma chemical & pathalohical process
5 endothelium-contain hexagonal cells single layer
-cells do not proliferate and it is compansated by polymegathism

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2
Q

Congenital anomalies of cornea

A

Megalocornea
Micro cornea
Cornea plana
Cloudy cornea

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3
Q

Morphological classification of corneal ulcers

A

Ulcerative keratitis

Non ulcerative keratitis

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4
Q

Ulcerative keratitis

A 
1.depending upon location 
2 depending upon purulence
3 depending upon hypopyon
4 depending upon depth
5 depending upon slough formation
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5
Q

Non ulcerative keratitis

A 
1 superficial 
-diffuse 
-punctate
2 deep keratitis 
-non suppurative 
-suppurative
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6
Q

Etiological classification of keratitis

A

1 infective
2 allergic
3 trophic
4 associated with disease of skin and mucous
5 associated with systemic collagen disease
6 idiopathic keratitis
6 traumatic keratitis

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7
Q

Organisms which invades intact corneal epithelium

A

1 neisseria gonorrhoeae
2 corynebacterium diphtheria
3 neisseria meningitidis

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8
Q

Aetiology of bacterial corneal ulcers

A

2 thing are responsible
• damage of corneal endothelium
• infection of eroded area

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9
Q

Corneal epithelial damage of bacterial corneal ulcers

A
  • corneal abrasion
  • epithelial drying
  • necrosis
  • epithelial damage
  • desquamation of epithelial cells
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10
Q

Source of infection of bacterial corneal ulcers

A
  • exogeneous
  • endogenous
  • secondary
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11
Q

Causative organisms of bacterial corneal ulcers

A 
Staphylococcus 
Streptococcus 
N.gonorrhoeae
N.meningitidis
Corynebacterium diphtheria 
E.coli 
Proteus
Klebsiella
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12
Q

Stages of bacterial corneal ulcers

A

1 stage of progressive infiltration
2 stage of active ulceration
3 stage of regression
4 stage of cicatrisation

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13
Q

Based on virulence, host defence and treatment corneal ulcers may be

A

Localised
Perforating
Sloughing

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14
Q

Symptoms of corneal ulcers

A 
Pain 
Photophobia 
Lacrimation 
Redness 
Diminution of vision 
Blepharospasm
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15
Q

Sign of corneal ulcers

A 
Lid- oedema 
Conjuctiva-chemosis & congestion 
Ciliary-congestion 
Corneal ulcers-yellowish-white
-irregular shape
-margins swollen 
-floor contains necrotic debris
Anterior chamber-hypopyon may be or may not be
Iris - muddy colour 
Pupil-small or constricted 
IOL-may be raised
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16
Q

Treatment of uncomplicated corneal ulcers

A 
1 antibiotics 
• vancomycin and ciprofloxacin 
• cefazolin and amikacin 
2 supportive 
• cycloplegic
• anti inflammatory & analgesic 
• vitamins
3 general measures 
• Hot fomentation
• dark goggles 
• rest,good diet,fresh air
17
Q

Treatment of non healing corneal ulcers

A 
1 treatment of underlying cause
2 debridement
3 cauterisation 
4 bandage soft contact lens
5 peritomy
18
Q

Treatment of impending perforating corneal ulcers

A 
1 no strains 
2 pressure bandage
3 lowering of IOL
4 tissue adhesive glue
5 bandage soft contact lens
6 conjunctival flaps
7 amniotic membrane transplantation 
8 penetrating therapeutic keratoplasty
19
Q

Treatment of perforated corneal ulcers

A 
Best option is therapeutic keratoplasty but, 
These can be done 
•tissue adhesive glue 
•conjunctival flaps
•use of bandage soft contact lens 
•keratoplasty
20
Q

Complications of corneal ulcers

A 
1 toxic iridocyclitis
2 secondary glaucoma 
3 descematocele
4 perforation of ulcer
5 scarring
21
Q

Complications of perforated corneal ulcerS

A 
1 prolapse of iris
2 subluxation of lens
3 anterior capsular cataract 
4 corneal fistula 
5 uveitis 
6 endopthalmitis 
7 panopthalmitis 
8 intraocular haemorrhage in for of vitreous or choroidal haemorrhage
22
Q

Hypopyon corneal ulcers

A

Characteristic ulcer caused by pneumococcus

Also called ulcus Serpens

23
Q

Aetiology of hypopyon corneal ulcers

A

Causative organisms- pneumococcus

Source of infection- chronic dacryocystitis

24
Q

Mechanism of hypopyon corneal ulcers

A

Diffusion of toxins causes iritis in corneal ulcer caused by pneumococcus
Because of iritis leukocyte gravitate at the bottom in anterior chamber in the form of pus

25
Q

Symptoms of hypopyon corneal ulcers

A 
Pain 
Photophobia 
Redness
Lacrimation 
Foreign body sensation 
Diminution of vision 
Blepharospasm
26
Q

Signs of hypopyon corneal ulcers

A

In general signs are same as bacterial corneal ulcers

Specific characteristics-
• yellowish white occurring near centre
• ulcer has tendency to creep over cornea in serpiginous fashen
• violent iridocyclitis is present

27
Q

Mycotic corneal ulcers

A

It refers to fungal corneal ulcer
It is suppurative ulcer
It’s incidence increased in recent years because of injudicious use of steroids and antibiotics

28
Q

Aetiology of Mycotic corneal ulcers

A

Causative organisms-
aspergillus,fusarium,cephalosporiums,penicilliums,candida & cryptococcus

Mode of injury-
•injury by vegetative material
•injury by animal tail
•secondary fungal ulcers

Role of antibiotics

29
Q

Symptoms of Mycotic corneal ulcers

A

Same as bacterial ulcers but are less marked and slow

30
Q

Signs of Mycotic corneal ulcers

A

-ulcer is dry looking and greyish white
Feathery finger like extension are present in stroma
Sterile immune ring is present
Small satellite lesions may be present around lesion
Big hypopyon is present
Perforation is rare

31
Q

Treatment of Mycotic corneal ulcers

A

Specific treatment
• topical - natamycin, amphotericin b fluconazole & nystatin
•Systemic- in severe case ex: fluconazole & ketoconazole

Non specific treatment

Therapeutic penetrating keratoplasty

32
Q

Cornea

A

Transparent
Avascular
Watch glasslike structure

opthalmology by sayeed (4 decks)

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