20: Dyes

Question 1

the 3 dyes most commonly used in eye-care practitioner’s office today is

Answer 1

• fluorescein
• rose bengal
• lissamine green

Question 2

what does fluorescein interact with intact corneal epithelium

Answer 2

it resists penetration of the dye, due to high degree of ionization at physiologic pH and will not be colored

Question 3

how is fluorescein used in dry eye and what are some limitations?

Answer 3

• 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

Question 4

ADEs/cautions for topical admin of Fluorescein strips

Answer 4

minimal side effects, except for staining of soft contact lenses

Question 5

ADEs/cautions for injectable admin of Fluorescein strips

Answer 5

susceptible to bacterial contamination
(pseudomonas aeruginosa grows easily)
-nausea, GI distress, headache

Question 6

when do you use fluorescein injectables?

Answer 6

in fluorescein angiography (or retinal angiography) which is indicated for evaluation of the retinal vascular system

Question 7

what is the difference between fluorescein and fluorexon?

Answer 7

• 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)

Question 8

indications for use of fluorexon

Answer 8

-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

Question 9

in fluorexon, how does the water content relate to potential for staining?

Answer 9

the higher the water content the greater potential for staining of the lenses

Question 10

what is the chemical makeup of rose bengal and what allergies need to be asked about?

Answer 10

• an iodine derivative of fluorescein

- ask about allergies to iodine and shellfish

Question 11

what does rose bengal stain?

Answer 11

dead cells, degenerated cells, and mucus strands similar to fluorexon

• stains bright pink or magenta
• will also stain normal, healthy, living cells

Question 12

key indications of rose bengal

Answer 12

• dry eye syndromes (most diagnostic for early to moderate dry eye
• herpetic corneal epithelial dendrites/keratitis

Question 13

what one caution of using rose bengal before cultures and why?

Answer 13

• it has antiviral activity, so may preclude adequate detection (false neg culture) if used prior to cultures
• similar to lissamine green

Question 14

ADEs/ cautions for rose bengal

Answer 14

• can cause irritation and discomfort, more than fluorescein or lissamine green
• can burn upon instillation (so its used less than lissamine green)

Question 15

how is lissamine green similar and different to rose bengal

Answer 15

• 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

Question 16

chemical makeup and possible allergies in Indocyanine Green

Answer 16

• water soluble tricarbocyanine dye

- contains sodium iodide (Similar to rose bengal) so ask about allergies to iodine and shellfish

Question 17

Indocyanine Green injectable is used in

Answer 17

retinal and choroidal angiography

Question 18

what is Indocyanine Green used most frequently to identify

Answer 18

to identify and characterize choroidal neovascularization

Question 19

how is Indocyanine Green better/worse then fluorescein injectable

Answer 19

• better visualization of deeper choroidal blood vessels

- lesser resolution of retinal vasculature