Microbiology

Question 1

chemical properties of the eye to prevent infection

Answer 1

lysozyme to destroy bacterial cell walls
lipids and IgA to prevent attachment
interleukins to allow immune regulation

Question 2

physical features of the blink reflex to prevent infection

Answer 2

tears flush dirt and bacteria from eye

mucus layer on top of cornea as anti-adhesive

Question 3

what function does the langerhans cell have in immune regulation within the eye and where is it present

Answer 3

principle APC for external eye
corneo-scleral limbus and in peripheral cornea
absent from central cornea

Question 4

what is the only part of the eye with lymphatic drainage

Answer 4

conjunctiva

Question 5

describe immune properties of the conjunctiva for fighting infection

Answer 5

dendritic cells, langerhans
travel to MALT if required
mast cells, macrophages and langerhans are all present in MALT

Question 6

describe immune properties of the sclera and cornea for fighting infection

Answer 6

no lymphatics or MALT
lack of APC
langerhans is present in the peripheral cornea
downregulated environment

Question 7

describe the immune properties of the lacrimal gland and drainage system

Answer 7

plasma cells secreting IgA and CD8+T cells in small groups
resting lymphoid cells rare
diffuse MALT in the drainage system

Question 8

describe immune privilege and sites that may have it

Answer 8

placenta and foetus 
eye 
brain 
testes 
can tolerate introduction of antigens without eliciting inflammatory immune response

Question 9

what properties allow the eye to have immune privilege

Answer 9

blood tissue barrier
lack of lymphoid drainage
immune suppressive molecules

Question 10

what is symptathetic ophthalmia

Answer 10

rare and bilateral uveitis due to trauma/surgery to one eye
AA reaction to ocular antigens due to event
immune response at elevated rate with CD4/CD8 T cells
these are activated by antigens and respond to the antigens in both eyes

Question 11

sympathetic ophthalmia - injured eye is the exciting/sympathising eye and the other is the exciting/sympathising eye

Answer 11

injured is exciting

other is sympathising

Question 12

how can you tell the exciting and sympathising eye apart in sympathetic ophthalmia

Answer 12

the history alone

Question 13

what is ocular cicatrical pemphigoid

Answer 13

blistering autoimmune conjunctavitis leading to scarring
can lead to adhesions of conjunctiva and sclera leading to ectropia
manage with high dose steroids

Question 14

example of type 3 sensitivity to eye

Answer 14

autoimmune corneal melt

Question 15

example of a type 4 hypersensitivity to eye

Answer 15

corneal graft rejection

Question 16

what causes corneal graft rejection

Answer 16

vascularisation of host cornea reaching donor tissue and leading to immune response

Question 17

factors of immune privilege that prevent corneal graft rejection

Answer 17

reduced MCH I/II
lack of blood and lymph supply to cornea
central cornea deficient in langerhans cells
immunosuppressive molecules and inhibition of immune mediators

Question 18

side effects of steroid therapy on the eye?

Answer 18

steroid induced glaucoma

cataracts

Question 19

bacteria in neonatal bacterial conjunctavitis?

Answer 19

MUST refer
n gonorrhoeae
staph aureus
chlamydia

Question 20

bacteria in child/adult bacterial conjunctavitis

Answer 20

h influenzae in children
staph aureus
strep pneumoniae

Question 21

management of bacterial conjunctavitis?

Answer 21

swab

topical abx - chloramphenicol drop/ointment 4 daily

Question 22

side effects/contraindication chloramphenicol?

Answer 22

allergy, aplastic anaemia

worsening symptoms may mean allergy

Question 23

microbes in viral conjunctavitis

Answer 23

adenovirus - following URTI
herpes simplex
herpes zoster

Question 24

presentation of viral conjunctivitis

Answer 24

red eye, profuse watering

hutchisons sign in shingles

Question 25

presentation of bacterial keratitis

Answer 25

whitening of cornea | hypopyon

Question 26

who is more likely to get bacterial keratitis

Answer 26

people with other eye pathologies or contact lens wearers

Question 27

management of bacterial keratitis

Answer 27

``` admit hourly eye drops daily review local anaesthetic, removal, swab can lead to cornea rupture ```

Question 28

how may viral keratitis be managed

Answer 28

ganiclovir | do not treat with steroids as may lead to corneal melt

Question 29

presentation of herpes viral keratitis

Answer 29

little vesicles round eye and maxilla painful dendritic appearance on stain

Question 30

presentation of adenovirus viral keratitis

Answer 30

dimples, reduced vision painful bilateral may follow URTI or conjunctivitis

Question 31

in who is fungal keratitis more common and how is it treated

Answer 31

ocular surface disease, those who work outside defined corneal lesions anti-fungals

Question 32

what is acanthomoeba

Answer 32

parasite specific to contact lens wearers usually due to rinsing contacts under tap water ring like deposit on cornea culture contact lenses

Question 33

presentation of preseptal cellulitis and management

Answer 33

shiny, red tight around eyelid | fluclox usually settles, may be needed systemic

Question 34

presentation of orbital cellulitis

Answer 34

pain, esp on eye movement proptosis involvement with paranasal sinuses pyrexia

Question 35

treatment of orbital cellulitis

Answer 35

broad spec systemic abx drainage of abscesses CT scanning

Question 36

organisms in orbital cellulitis

Answer 36

staph/strep coliforms h influenzae anaerobes

Question 37

diagnosis of orbital cellulitis

Answer 37

CT urgent visual function redness of entire orbital wall hx

Question 38

what is endopthalmitis and what causes it

Answer 38

devastating infection in inside of eye sight threatening post surgical/endogenous

Question 39

presentation of endopthalmitis

Answer 39

highly painful and red eye with decreasing vision

Question 40

management of endopthalmitis

Answer 40

intra-vitreal abx directly sample then take abx topical bx systemic abx dont do much

Question 41

management of CMV chorioretinitis and what causes it

Answer 41

HIV/AIDS | intra-vitreal antiviral drugs

Question 42

what viruses can lead to acute retinal necrosis

Answer 42

HSV/HZV

Question 43

presentation of toxoplasma chorioretinitis, where is it caught

Answer 43

mild flu like illness | congenital or acquired from contaminated soil, undercooked meat

Question 44

how may toxoplasma/toxocara cause retinal issues

Answer 44

may lead to retinal scarring and may be incidental | can reactivate

Question 45

how is toxoplasma causing sight threatening damage managed

Answer 45

systemic clidamycin/azithromycin with steroids

Question 46

cause of candida chorioretinitis

Answer 46

endocarditis, indwelling catheters, central lines

Question 47

what are swabs suited for in eye infection

Answer 47

bacteria viruses chamydia

Question 48

what are corneal scrapes suited for in eye infection

Answer 48

fungi

Question 49

what are aqueous/vitreous cultures indicated for

Answer 49

endopthalmitis

Question 50

what is serology in eye infection indicated for

Answer 50

toxoplasma/toxocara

Question 51

what is microscopy and culture indicated for in eye infection

Answer 51

acanthomoeba

Question 52

management of chlamydial conjunctavitis

Answer 52

topical oxytetracycline

Question 53

how does chloramphenicol work and side effects

Answer 53

inhibits bacterial peptidyl transferase | irreversible aplastic anaemia, grey baby syndrome, allergy

Question 54

how do quinolones work, what are they and what do they treat

Answer 54

inhibit gyrase gentamicin, cefuroxime treat most gram -ves, coliforms and pseudomonas

Question 55

what are the issues from storing eye drop bottles with preservatives

Answer 55

can contaminate to culture pseudomonas

Question 56

indication for ganiclovir and how does it work

Answer 56

inhibits viral DNA synthesis | dendritic ulcers of cornea