pharmacology week 6 -opthalmic dye staining agents

what are the use of staining agents

• examination of anterior eye

• evaluation of lacrimal drainage system

• contact lenses( fit assessment,aftercare)

• tonometry

• angiography

what are we examining in anterior eye

cornea

conjuctiva

Tear film

what dyes are relevant to optoms

flourescine sodium

rose bengal

lissamine green

when is floruescine used (lots of examples)

• corneal epithelium and conjuctiva integrity (dry eye, suspected trauma, suspected foreign body, CL aftercare)

• fit of RGP

• contact tonometry- Goldman (to see mires)

• examination of lacrimal drainage and TF

• floruescin angiography

• suspected penetrating injury 

how is it administered for angiography

intravenous administration

what’s been identified here

dendritic ulcer in Herpes simplex virus

what has been identified

a superiore epithelial arcuate lesion

when does this occur

typically in silicone hygrogel lenses - more rigid

how does floruescine work

• mixes with TF( does not stain cells itself) then tear film enters damaged cells or tissues

• pH indicator

• highly ionised at physiological pH

when does it not penetrate the cornea

because it has low lipid solubility

what factors affect florescence

• pH highest at 8

• concentration ( only occurs below 1%)

• intensity and wavelength of incident light

what incident light is best

475- 535nm

suitable light sources

• cobalt blue filter with wratten filter

• white light- fluoresces but low contrast

• UV tube in Burton lamp

what does the wratten filter do

increases contrast

where is wratten filter placed

placed in front of observation system only not illumination

NaFL availability

Fl impregnated strips-1mg fl

minims of NAFl(1% and 2% single eye drops)

minims of lidocaine (1%)and FL(0.25%)

is Fl a PoM

no

Fl installation

• explain procedure to px

• 4- D test ( drug,dose, date, disposal)

• wet with saline

• apply to inferior bulbar conductive by lowering eyelid

• px blinks to distribute

how does Rose bengal work

• stains cells and its nucleus red( dead corneal and conjunctival cell and mucus)

• potent stain

what main clinical identification does it cause

identification of keratoconjuctivis- dryness of anterior ocular surface due to TF, blinking, or lid deficiencies

Lissamine green what does it stain

• degenerated cells, dead cells and mucus

other features 

less irritation that rose bengal

long lasting staining

light absorption for LG

peak at 624-635nm

how is it used

q.5mg impregnated strip

white light

view 1-4 min post installation

what is indocyanaine green used for

used in angiography

reacts to longer wavelength than Fl

detects leakage at deeper levels(retina/choroid)

peak excitation at 805nm