diagnostic stains Flashcards
name 3 diagnostic staines
- fluorescein sodium
- rose bengal
- lissamine green
which stain will you use to see things on the cornea
flourescein
which stain will you use to see things on the conjunctiva
rose bengal and lissamine green
which 2 ways can flourescein be used
- topically
or - injected systemically for flourescein angiography
what is always at hand when doing flourescein angiography and why
defibrillator because it can cause a cardiac arrest
explain why flourescein is not a true stain
- it colours the tear film
- the tear film does not invade intact corneal epithelium (i.e. it can’t pass through the cornea unless it has an abrasion and thats when flourescein enters it)
- lipid membrane impermeable to water soluble polar water molecules
- epithelial damage means flourescein can gain access to deeper layers
what spectrum of absorbed energy maximally excites flourescein molecules
light thats absorbed maximally between 485 - 500nm (blue)
what nm of light does flourescein emit
between 525 - 530nm (green)
what wavelength of light does the burton lamp emit
305 - 410nm
what wavelengths do some RGPs absorb light between
315 - 400nm
what wavelength of light does the blue filter on the slit lamp emit
390 - 410nm
list 6 uses of flourescein
- assessment of corneal integrity (trauma, disease, contact lens a/c)
- rigid contact lens fitting
- contact tonometry
- TBUT
- lacrimal patency
- lacrimal drainage
how is lacrimal drainage assessed with flourescein
- px to blow nose and check if tissue is orange
- if not orange then means theres a blockage in the puncta
- can also monitor the amount of flourescein that is still in the eye so can check if conjunctiva still has flourescein which means it still hasn’t drained away
what are the 2 contraindications of flourescein sodium
- known sensitivity
- dont put in with soft cl’s
what is the caution of the multi dose bottles of flourescein
- contamination problems in hospitals in the 1950’s
- flourescein is used on damaged cornea
- pseudomonas has an affinity for flourescein
- this progresses rapidly and can cause corneal perforation within 48 hours
how rapidly can pseudomonas progress and cause corneal perforation/ulcers
within 48 hours
what 2 forms of packaging is flourescein available in, what are the doses and what is the storage requirement
- minims 1% and 2%
- flourescein impregnated strip 1mg
- store below 25 degrees celsius
what 4 properties are thee about flourescein minims
- orange-yellow
- slightly alkaline
- contains buffer to stabilise solution
- may be combined with anaesthetic
what is rose bengal a derivative of
flourescein
what structures does rose bengal stain
- devitalised epithelial cells of cornea and conjunctiva
- stains mucous strands
what type of effect does rose bengal have
anti viral
rose bengal _________ on instillation, especially in ______ ______ conditions
rose bengal stings on instillation, especially in dry eye conditions
rose bengal may cause _____________ staining
rose bengal may cause punctate staining
rose bengal has a _________ effect on human _________ epithelial cells, enhanced by ____________ ___________
rose bengal has a toxic effect on human corneal epithelial cells, enhanced by light exposure
what forms of packaging and dosage has rose bengal been available in
- 1% minims (not commercially available)
- ophthalmic strips 1.3mg
list 5 conditions where rose bengal is useful
- keratoconjunctivitis sicca
- dendritic keratitis
- neuroparalytic keratitis
- exophthalmos
- pressure areas due to contact lens wear
what form of packaging and dose is lissamine green available in
ophthalmic strips 1.5mg
what are the actions of lissamine green similar to
rose bengal
list 5 ways in which lissamine green differs from rose bengal
- stings less
- less toxic
- no anti viral effects
- staining effect lasts longer than rose bengal
- it does not stain healthy cells like rose bengal does
how are the actions of lissamine green similar to rose bengal
like rose bengal it binds to severely damaged cells and is easier to view against lighter irises
when should you observe your staining after instilling lissamine green and why
1-4 minutes
- if observe too soon, staining pattern won’t have developed
- if observe too late, some of the staining pattern may have faded away
what illumination must you begin with when observing lissamine green and why
start off with low illumination as high illumination will bleach out the appearance of some staining
what can be used when observing staining with lissamine green that will help
red filter wratten no. 25
there is some evidence to suggest that early signs of ______ ______ disease is more ____________ with lissamine green compared to ______________
there is some evidence to suggest that early signs of dry eye disease is more visible with lissamine green compared to flourescein
for the evaluation of staining, can use charts e.g. __________ grading scheme, but _____________ may be poor
for the evaluation of staining, can use charts e.g. oxford grading scheme, but repeatability may be poor
list 5 other stains which are not used commercially
- alcian blue
- trypan blue
- bromothymol blue
- methylene blue
- tetrazolium and iodonitrotetrazolium
what does aclian blue stain
mucus
what does trepan blue stain
mucus and dead cells which have undergone structural changes
what does bromothymol blue stain
degenerate and dead cells, mucus used to investigate damage by chemical agents
what does methylene blue stain
bacterial stain that will also stain nerve tissue
what does tetrazolium and iodonitrotetrazolium stain
tetrazolium stains degenerate cells (not living or dead), staining of tumours and assessing corneal grafts
