Diagnostic Stains Flashcards
what type of light do diagnostic stains emit?
lower energy (longer wavelength) - molecule will absorb highest energy (shortest wavelength)
are diagnostic stains acidic or basic?
can be either but not neutral
Is fluorescein water or oil soluble? and where is it ionized?
water soluble and ionized in the tears (hydrophilic)
When will fluorescein be able to enter the cornea (lipophilic)?
cornea will be compromised (not intact) - dry eye, abrasion, ulcer, lesions - tight junctions are broken = corneal staining
what is absorption of fluorescein for tissue and blood?
excited by 493nm (cobalt blue) and 465nm in bloodstream
why does the blood need a higher energy to become excited?
binding in the blood to albumin and RBC’s reduces the activity
what is the emission of fluorescein?
520nm (yellow/green color is seen)
what color of fluorescein is seen on the tear film?
orange/yellow/green –> need to enhance with a wratten filter
what is seidel’s sign?
used to assess the presence of anterior chamber leakage through the cornea from a penetrating injury (will see fluorescent green in bowman’s membrane or aqueous humor)
what is quenching?
some atoms or molecules can facilitate non-radiative transitions to ground state (occurs without emitting photo - steals the energy)
which anesthetic causes the least amount of quenching? what about the most?
least = BAK + benoxinate middle = proparacine most = tetracaine
what happens to IOP readings with fluorescein quenching?
intensity is diminished - underestimation of IOP
how can fluorescein detect an ulcer?
penetration below basement membrane of corneal epithelium - exposes the stroma = dye will disperse 360 in eye
how can fluorescein detect an alkaline burn?
chemicals/molecules will precipitate by biding with a salt and deposit in the lower fornix - will stain will dye
how can fluorescein evaluate tear break-up time (TBUT)?
after complete blink - look for the first randomly distributed dark spot in tear film (interval = TBUT)
how can fluorescein be used to evaluate RGP CL adaptation?
anywhere you see dye it is trapped under the lens - not in absolute contact with the eye (need different lens if no dye is seen)
how do you use a Wratten filter when elvauating RGP fit?
filter is required over the light source
how can fluorescein be used to diagnose a tear duct obstruction/epiphora?
use with a Jones test
how is fluorescein used with aniline dye from indelible pencils?
it is an antidote - methyl violet spreads through ocular tissues and is precipitated by 2% sodium fluorescein
how can you measure aqueous humor production with fluorescein?
patient drinks dye –> goes into bloodstream and to the eye (watch appearance in anterior chamber)
how can fluorescein be used to distinguish between viral keratitis caused by herpes simplex or herpes zoster?
dye highlights the filaments
simplex = bulb-like ends
zoster = thin ends
How is fluorescein used in angiography?
used to visualize structural defects, vascular pathology, tumors, RPE thinning, CME, AMD (10-15 sec to arrive at retina)
After administering fluorescein to antecubital vein, what do you watch for on the fundus photos?
any areas of pooling in the macula = diabetes, AMD, Stargardt’s disease and tumors
What are HMW (high molecular weight) fluorescein formulations used for?
used with soft CL because they can stain with LMW - the HMW are too large to be absorbed by the lens
What are some examples of topical fluorescein formulations?
Fluoracaine + proparacine, Fluress + benoxinate, and Flu-Glo (strips)
What are some examples of HMW fluorescein formulation?
Fluoresoft PF and Fluora-safe + benoxinate and SoftGlo
What allergies should you avoid giving fluorescein to?
ester anesthetics - PABA
What are some common adverse reactions to topical fluorescein?
string, irritation, redness, dermatitis, nausea and headaches
What pregnancy category is fluorescein?
C
What are some serious adverse reactions to topical fluorescein?
corneal hypersensitivity, epithelial keratopathy, seizures, CNS depression, anaphylaxis
What is the absorption for Rose Bengal?
545-490nm
What does Rose Bengal stain?
mucus or devitalized tissue
What color do degenerated/dead cells stain with Rose Bengal?
mildly degenerated cells = light red
severely degenerated cells = dark red
dead cells = intense red
What filter do you use to view Rose Bengal?
viewed under white light or red-free (green filter) –> blocks red light - only allowing green through
Why is it necessary to collect cultures before using rose bengal or lissamine green?
they have mild anti-viral properties
What is the purpose of using Rose Bengal?
to detect if there is reduced tear volume through detection of damaged epithelial cells
How can rose bengal be used to detect HSVK?
RB stains the damaged epithelial cells on the border of an HSVK ulcer
What are some conditions rose bengal is used for in detection?
keratoconjunctivitis sicca (KCS), superior limbic keratoconjunctivities (SLK), herpes zoster/simplex
What are the adverse side effects of rose bengal?
irritating to eye (use with anesthetic) and may have hypersensitivity (iodine-based)
What does lissamine green stain?
mucus or devitalized tissue
How is lissamine green better than rose bengal in staining?
better contrast in red, inflamed or hemorrhagic eyes and is longer lasting without irritation
What is the absorption for lissamine green?
567-634nm
What filters is lissamine green viewed under?
white light or red filter (green-free) - blocks out green light and only allows red (green appears black)
When is lissamine green used?
KCS (dry eyes), superior limbic KC, herpes simplex/zoster
What are some adverse effects of lissamine green?
minimal irritation (less than RB), itch, hypersensitivity (rare)
What is fluramene?
Fluorescein and lissamine green together
When is fluramene used?
for corneal and conjunctival staining simultaneously (devitalized tissue, mucus, corneal surface irregularities)
What is indocyanine green?
used in ophthalmology as an IV stain
What is the absorption for indocyanine green?
790nm
How is indocyanine green different from fluorescein?
it doesn’t leak from the choriocapillaries, RPE doesn’t block its emission spectrum, and it is the best dye for CNVM (AMD)
