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Opthalmo > Cornea & Sclera > Flashcards

Cornea & Sclera Flashcards

1
Q

What are the 5 layers of the cornea?

A

1) Epithelium
2) Bowman membrane
3) Stroma
4) Descemet membrane
5) Endothelium

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2
Q

What is the histology of the corneal epithelium?

A

Non- keratinized stratified
squamous

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3
Q

The corneal epithelium regenerates from __ found in the __.

A

Stem cells; Limbus

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4
Q

Which layer gives 90% of the corneal thickness? Which fibrils does it contain?

A

Stroma; parallel collagen fibrils

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5
Q

What is the role of the corneal endothelium?

A

Non-regenerating cells that actively pump water from the stroma to control hydration of the cornea

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6
Q

What happens if the corneal endothelium is damaged?

A

1) Edema
2) Corneal clouding

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7
Q

The cornea derives its nutrition almost entirely from:

A

Aqueous humour

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8
Q

The cornea is rich in sensory nerve endings originating from:

A

The nasociliary branch of trigeminal nerve

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9
Q

What is the function of the cornea?

A

1) Protection of internal ocular structures
2) Refraction

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10
Q

Refractive components of the eye or the focusing power is:

A

1) 2/3 cornea, fixed power
2) 1/3 lens, power increases with accommodation

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11
Q

Herpes Simplex and Zoster Keratitis are characterized by:

A

The appearance of dendritic ulcers on the cornea, which usually heal without scar

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12
Q

Which virus is the most common cause of Herpes Simplex and Zoster Keratitis?

A

HSV-1

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13
Q

What are the signs & symptoms of Herpes Simplex and Zoster Keratitis?

A

1) Very painful
2) Photophobia
3) Watery discharge
4) Eyelid swelling
5) Dendritic ulcer

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14
Q

The pathognomonic appearance of Herpes Simplex and Zoster Keratitis is:

A

Dendritic ulcers

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15
Q

How do HZV skin lesions start?

A

As vesicles at ophthalmic division of trigeminal

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16
Q

HZV ocular problems are more likely if:

A

The nasociliary branch is involved = Hutchinson’s sign

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17
Q

Treatment for Herpes Simplex and Zoster Keratitis lesions?

A

1) Topical antiviral for dendritic ulcer (acyclovir)

2) Oral antiviral in HZV with skin involvement, will reduce post herpetic neuralgia

18
Q

Should topical steroids be used in patients with dendritic ulcers?

A

No; they may cause more extensive ulceration

19
Q

The cornea is protected against infection by:

A

1) Blinking
2) Washing of debris by the flow of tears
3) Entrapment of foreign particles by mucus
4) Anti-microbial properties of tear
5) The barrier function of the corneal epithelium

20
Q

__ is the only organism
that can penetrate the intact corneal epithelium

A

Neisseria gonorrhoeae

21
Q

Predisposing factors for bacterial keratitis:

A

1) Keratoconjunctivitis sicca (dry eye)
2) A breach in the corneal epithelium
3) Contact lens use
4) Prolonged use of topical steroids

22
Q

Signs & symptoms of bacterial keratitis?

A

1) Pain
2) Purulent discharge
3) Ciliary injection
4) Visual loss
5) Hypopyon

23
Q

What is hypopyon?

A

White cells collected in the anterior chamber

24
Q

Treatment of bacterial keratitis?

A

1) Combined topical antibiotics to cover G+ve and G-ve
2) Fluorquinolones can be used as monotherapy

25
Q

Acanthameba Keratitis is caused by:

A

Protozoa

26
Q

Ring shaped abscesses are found in __.

A

Acanthameba Keratitis

27
Q

Acanthameba Keratitis treatment?

A

Chlorhexidene and propamidine for months and may end by corneal graft

28
Q

Fungal Keratitis should be considered in:

A

1) Lack of response to antibacterial therapy
2) Cases associated with prolong use of steroids
3) History of trauma by plants

29
Q

Corneal dystrophies are divided into:

A

1) Anterior Dystrophies

2) Stromal Dystrophies: present with visual loss

3) Posterior Dystrophies: gradual visual loss

30
Q

Anterior corneal dystrophies present with:

A

Recurrent corneal erosion

31
Q

What is Keratoconus?

A

Sporadic disorder associated with thinning of the center of the cornea leads to ectasia and cone shaped cornea

32
Q

Signs & symptoms of keratoconus?

A

1) Myopia
2) Astigmatism

NO PAIN

33
Q

How is keratoconus diagnosed?

A

Corneal topography

34
Q

Keratoconus treatment?

A

1) Spectacles
2) Contact lenses
3) Corneal cross linking
4) Intra stromal corneal rings
5) Corneal graft
6) CROSS LINKING

35
Q

What is the sclera composed of?

A

Interwoven collagen fibrils of different widths

36
Q

All six extraocular muscles are inserted on the __.

A

Sclera

37
Q

Scleritis is usually associated with __.

A

Collagen vascular disease most
commonly RA

38
Q

Complications of scleritis?

A

1) Sclermalacia (scleral thinning) sometimes with perforation
2) Keratitis
3) Uveitis
4) Cataract formation
5) Glaucoma

39
Q

Management of mild scleritis?

A

Topical steroids and oral NSAIDs

40
Q

Management of moderate and severe scleritis?

A

By high doses of systemic
steroids or Cytotoxics

Opthalmo (10 decks)

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