Cornea & Sclera

Question 1

What are the 5 layers of the cornea?

Answer 1

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

Question 2

What is the histology of the corneal epithelium?

Answer 2

Non- keratinized stratified
squamous

Question 3

The corneal epithelium regenerates from __ found in the __.

Answer 3

Stem cells; Limbus

Question 4

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

Answer 4

Stroma; parallel collagen fibrils

Question 5

What is the role of the corneal endothelium?

Answer 5

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

Question 6

What happens if the corneal endothelium is damaged?

Answer 6

1) Edema
2) Corneal clouding

Question 7

The cornea derives its nutrition almost entirely from:

Answer 7

Aqueous humour

Question 8

The cornea is rich in sensory nerve endings originating from:

Answer 8

The nasociliary branch of trigeminal nerve

Question 9

What is the function of the cornea?

Answer 9

1) Protection of internal ocular structures
2) Refraction

Question 10

Refractive components of the eye or the focusing power is:

Answer 10

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

Question 11

Herpes Simplex and Zoster Keratitis are characterized by:

Answer 11

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

Question 12

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

Answer 12

HSV-1

Question 13

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

Answer 13

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

Question 14

The pathognomonic appearance of Herpes Simplex and Zoster Keratitis is:

Answer 14

Dendritic ulcers

Question 15

How do HZV skin lesions start?

Answer 15

As vesicles at ophthalmic division of trigeminal

Question 16

HZV ocular problems are more likely if:

Answer 16

The nasociliary branch is involved = Hutchinson’s sign

Question 17

Treatment for Herpes Simplex and Zoster Keratitis lesions?

Answer 17

1) Topical antiviral for dendritic ulcer (acyclovir)

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

Question 18

Should topical steroids be used in patients with dendritic ulcers?

Answer 18

No; they may cause more extensive ulceration

Question 19

The cornea is protected against infection by:

Answer 19

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

Question 20

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

Answer 20

Neisseria gonorrhoeae

Question 21

Predisposing factors for bacterial keratitis:

Answer 21

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

Question 22

Signs & symptoms of bacterial keratitis?

Answer 22

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

Question 23

What is hypopyon?

Answer 23

White cells collected in the anterior chamber

Question 24

Treatment of bacterial keratitis?

Answer 24

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

Question 25

Acanthameba Keratitis is caused by:

Answer 25

Protozoa

Question 26

Ring shaped abscesses are found in __.

Answer 26

Acanthameba Keratitis

Question 27

Acanthameba Keratitis treatment?

Answer 27

Chlorhexidene and propamidine for months and may end by corneal graft

Question 28

Fungal Keratitis should be considered in:

Answer 28

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

Question 29

Corneal dystrophies are divided into:

Answer 29

1) Anterior Dystrophies 2) Stromal Dystrophies: present with visual loss 3) Posterior Dystrophies: gradual visual loss

Question 30

Anterior corneal dystrophies present with:

Answer 30

Recurrent corneal erosion

Question 31

What is Keratoconus?

Answer 31

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

Question 32

Signs & symptoms of keratoconus?

Answer 32

1) Myopia 2) Astigmatism NO PAIN

Question 33

How is keratoconus diagnosed?

Answer 33

Corneal topography

Question 34

Keratoconus treatment?

Answer 34

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

Question 35

What is the sclera composed of?

Answer 35

Interwoven collagen fibrils of different widths

Question 36

All six extraocular muscles are inserted on the __.

Answer 36

Sclera

Question 37

Scleritis is usually associated with __.

Answer 37

Collagen vascular disease most commonly RA

Question 38

Complications of scleritis?

Answer 38

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

Question 39

Management of mild scleritis?

Answer 39

Topical steroids and oral NSAIDs

Question 40

Management of moderate and severe scleritis?

Answer 40

By high doses of systemic steroids or Cytotoxics