20: Dyes Flashcards
the 3 dyes most commonly used in eye-care practitioner’s office today is
- fluorescein
- rose bengal
- lissamine green
what does fluorescein interact with intact corneal epithelium
it resists penetration of the dye, due to high degree of ionization at physiologic pH and will not be colored
how is fluorescein used in dry eye and what are some limitations?
- most commonly used stain in dry eye
- only sufficiently stains cornea
- only in moderate to severe dry eye
- may miss most mild to moderate dry eye patients
ADEs/cautions for topical admin of Fluorescein strips
minimal side effects, except for staining of soft contact lenses
ADEs/cautions for injectable admin of Fluorescein strips
susceptible to bacterial contamination
(pseudomonas aeruginosa grows easily)
-nausea, GI distress, headache
when do you use fluorescein injectables?
in fluorescein angiography (or retinal angiography) which is indicated for evaluation of the retinal vascular system
what is the difference between fluorescein and fluorexon?
- fluorexon’s molecular weight is 2x
- it penetrates hydrophilic CL at a much slower rate
- less effective stain for epithelial defects, erosions, and CL induced effects than fluorescein
- will stain degenerated cells and mucus threads (like rose bengal)
indications for use of fluorexon
-an aid to hydrogen and other soft CL fittings, since due to its size it is less readily absorbed and does not stain most soft CL as easily as fluorescein
in fluorexon, how does the water content relate to potential for staining?
the higher the water content the greater potential for staining of the lenses
what is the chemical makeup of rose bengal and what allergies need to be asked about?
- an iodine derivative of fluorescein
- ask about allergies to iodine and shellfish
what does rose bengal stain?
dead cells, degenerated cells, and mucus strands similar to fluorexon
- stains bright pink or magenta
- will also stain normal, healthy, living cells
key indications of rose bengal
- dry eye syndromes (most diagnostic for early to moderate dry eye
- herpetic corneal epithelial dendrites/keratitis
what one caution of using rose bengal before cultures and why?
- it has antiviral activity, so may preclude adequate detection (false neg culture) if used prior to cultures
- similar to lissamine green
ADEs/ cautions for rose bengal
- can cause irritation and discomfort, more than fluorescein or lissamine green
- can burn upon instillation (so its used less than lissamine green)
how is lissamine green similar and different to rose bengal
- similar b/c it stains dead or degenerated corneal and conj. cells and precipitated mucus
- different b/c lissamine green doesn’t stain healthy ocular surface cells and has less irritation
