1 Flashcards
What is the % cross over at the chiasm for
Cat
Dog
Human
Cat 75%
Dog 65%
Human 50%
What is the Marcus Gunn sign?
What is it pathognomonic for?
Pupil suddenly dilates with direct illumination
Prechiasmal lesion (retina/ optic nerve)
What is the benefit of binocular indirect ophthalmology compared to monocular?
Assessing depth (stereopsis)
What does STT test
Basal and reflex tear production
What does tear film breakup time measure?
Mucin quality and quantity
How is does tear film breakup time performed?
What is a normal reading?
Add fluoro, close lids, look for black spots appear (dorsolateral area).
=>20s
What does the Seidel test show?
Shows aqueous leakage
What does fluorescein not stain (2)?
Descemets
Epithelium
What does rose bengal show?
Damaged or devitalised epithelium
How does applanation tonometry work? (Tonopen)
Measures force required to flatten the cornea
How does rebound tonometry work? (Tonovet)
Measures deceleration of magnetic probe on cornea
Which tonometry method does not need local anaesthetic?
Rebound tonometry (tonovet)
How long does tropicamide take to work?
How long does it last?
20-30mins
Lasts ~2h
If an ERG is normal in a blind eye what does this mean?
Retina is working but the cortex is not
If an ERG is abnormal in a blind eye what does this mean?
The retina is not working
