Diagnostic stains

Question 1

What are the different diagnostic stains?

Answer 1

Fluorescein

Lissamine green

Rose Bengal

Question 2

What are the uses for fluorescein?

Answer 2

• Assessment of corneal integrity – Trauma – Disease – Contact lens after-care
• Rigid contact lens fitting
• Contact tonometry
• TBUT
• Lacrimal patency (open)
• Lacrimal drainage

Question 3

What are the uses of rose bengal?

Answer 3

Staining of dead and devitalised cells in the cornea and conjunctiva - aids dry eye diagnosis.

Question 4

What are the uses of lissamine green?

Answer 4

Stains lipid-like structures, dead/dying epithelial cells, membrane damaged cells mucus. Does not stain healthy cells.

Question 5

What is the disadvantage ofn fluorescein?

Answer 5

Affinity of psuedonomas bacteria

Question 6

What are the disadvantages of using rose bengal?

Answer 6

Irritates dry eyes on instilation. Stings. Can also stain healthy cells

Question 7

Why is fluorescein deemed not a ‘true stain’?

Answer 7

Not a true stain • Colours the tear film - not the cornea as long as the tear film isn’t compromised

This is because the Lipid membrane part of tear film is impermeable to water • Epithelial damage means fluorescein can gain access to deeper layers

Question 8

When may fluorescein be injected into the eyes?

Answer 8

Injected systemically for fluorescein angiography

Question 9

What are contraindications of Fluroescein use?

Answer 9

– Known sensitivity – Soft contact lenses

Question 10

What are cautions to consider when using fluorescein?

Answer 10

Contamination problem in hospitals in 1950s – Fluorescein is used on damaged cornea – Pseudomonas has an affinity for fluorescein • Progresses rapidly • Corneal perforation within 48 hours

Question 11

What does rose bengal stain?

Answer 11

Stains devitalised epithelial cells of cornea and conjunctiva. Also stains mucous strands

Question 12

Does rose bengal sting on insertion?

Answer 12

Stings on insertion • Especially in dry eye conditions • Use anaesthetic? • May also cause punctate staining • Has toxic effect on human corneal epithelial cells, enhanced by light exposure

Question 13

What is rose bengal helpful for identifying?

Answer 13

Keratoconjuctivitis sicca Dendritic keratitis Neuroparalytic keratitis Exopthalmos Pressure areas due to contact lens wear

Question 14

What filter can be used with rose bengal stain?

Answer 14

A red free filter

Question 15

Describe lissamine green

Answer 15

■Actions similar to Rose bengal ■Stings less ■Less toxic ■No antiviral effects ■Like Rose bengal, binds to nuclei of severely damaged cells ■Staining effect lasts longer than Rose bengal

Question 16

What is the onset time for lissamine green?

Answer 16

Observe 1-4 minutes after instillation ■ Too soon-staining pattern won’t have developed. Too late-some of the pattern may fade ■ Begin with low illumination, high illumination will bleach out the appearance of some of the staining

Question 17

What may alcian blue stain be used for?

Answer 17

It stains mucus

Question 18

What does trypan blue stain?

Answer 18

Mucus and dead cells which have undergone structural changes

Question 19

What does Bromothymol blue stain?

Answer 19

Degenerate and dead cells, mucus, used to investigate damage by chemical agents

Question 20

What does Methylene blue stain?

Answer 20

Bacterial stain that will also stain nerve tissue

Question 21

What do Tetrazolium and Iodonitrotetrazolium stain?

Answer 21

Tetrazolium –stains degenerate cells (not living or dead) Staining of tumours and assessing corneal grafts