Cornea

Question 1

name the layers of cornea

Answer 1

epithelium (s,s & non-kera)
bowman layer
stroma
descement membrane
endothelium

Question 2

What supplies the cornea?

Answer 2

sensory n. endings via first division of trigeminal n.

Question 3

What are superficial lesions of cornea?

Answer 3

punctate epithelial erosison
punctate epithelial keratitis
epithelial oedema
filaments
pannus

Question 4

What are signs of corneal disease of stromal lesions?

Answer 4

infiltrates
oedema
vascularization

Question 5

What are lesions present on descement membrane of cornea?

Answer 5

breaks
folds

Question 6

What are optical methods used for cornea?

Answer 6

1. pachymetry (corneal thickness -> indicates integrity of corneal endothelium; limbus thickest part of cornea)
2. specular microscopy (photography of corneal endothelium (size, shape, density, & distribution)); normally hexagon shaped
3. keratometry (curvature of ant. corneal surface)
4. corneal topography (color-coded map of corneal surface (quantify astigmatism)

Question 7

Define agent, presentation, sign, & tx of bacterial keratitis

Answer 7

agent: neisseria gonorrhea & H. influenza (w/o compromisation of elithelial integrity) (contact lens wear, pre-existing corneal disease for other agents)

presentation: foreign body sensation, photophobia, blurring of vision, pain, eyelid oedema, discharge

signs: conjunctival injection, epithelial defect associated with an infiltrate, with progression stromal oedema, secondary sterile anterior uveitis, hypopyon (inflamed cells in ant. chamber), progressive ulceration, perforation

tx:
1. broad-spectrum topical antibiotics (dual therapy: aminoglycoside and cephalosporin, monotherapy: fluoroquinolone (corneal toxicity)
2. oral ciprofloxacin (to relieve ciliary spasm)
3. atropine (to relieve ciliary spasm)

Question 8

Define agent, presentation, sign, risk factors & tx of fungal keratitis

Answer 8

agents: filamentous fungi (aspergillus and fusarium spp.) and candida albicans

rf: ocular trauma involving organic matter such as wood or plants, pre-existing corneal disease, immunocompromisation

presentation: f.b. sensation, photophobia, blurred vision, & discharge
inappropriate use of topical steroids at time of dx
progression much slower & less painful than bact. infection

sign: grayish, stromal infiltrate with indistinct margins, surrounding satellite infiltrates

tx: topical treatment for 6wks (natamycin 5%, amphotericin 0.15%, imidazole 1% or flucytosine 1%), systemic antimycotics, therapeutic penetrating keratoplasty

Question 9

Define agent, presentation, sign, & tx of microbial keratitis

Answer 9

acanthamoeba keratitis:
hum. largely resistant may occur following minor corneal abrasion

presentation: blurred vision, severe pain which is characteristically disproportionate to clinical signs

sign: limbitis, small patchy anterior stromal and perineural infiltrates, central or paracentral ring abscess, slowly progressive stromal opacification, scleritis

investigations: non-nutrient agar seeded with E. coli or buffered charcoal-yeast extract

tx: topical amoebicides (propamidine isethionate 0.1%- brolene, polyhexamethylene biguanide 0.02%), topical steroids, therapeutic penetrating keratoplasty

Question 10

Define agent, presentation, sign, & tx of herpes simpley keratitis

Answer 10

agent: HSV-1

presentation: discomfort, watering & blurring of vision

types of keratitis:
epithelial keratitis (most common, branching like a tree, dendritic, corneal sensation is reduced)
disciform keratitis (endotheliitis, painless blurred vision, corneal sensation is reduced, central zone of epithelial oedema, stromal thickening, folds in descemet membrane, intraocular pressure may be elevated)
stromal necrotic keratiti: infilitrative, active viral invasion and tissue necrosis, discomfort and pain, impairment of vision, ant. uveitis)

acute retinal necrosis (immune deficiency)

tx:
topical/ systemic antivirals
steroids (stromal keratitis with an intact epithelium)

Question 11

If case says dendrities which agent do you have to think in relation to cornea?

Answer 11

HSV-1

Question 12

Define agent, presentation, sign, & tx of herpes zoster ophthalmicus

Answer 12

varicella zoster virus affects mainly elderly

may result in: epithelial keratitis and conjunctivits, stromal keratitis, uveitis, scleritis, and episcleritis

presentation: vesiicules on tip of nose, hutchinson sign (involv. of external nasal n.)

tx: systemic antivirals, topical steroid-antibiotic skin creams