Techniques Flashcards
For what diameter of cornea is Imbert-Fick true?
3.06mm
What is the Imbert-Fick law?
IOP = Contact force / area of contact
What assumptions are made in Imbert-Fick?
Assumes cornea is infinitely thin, perfectly elastic and perfectly flexible.
Why 3.06mm?
Corneal rigidity and tear film are roughly approximate so cancel each other out
Name four anaesthetics
Lignocaine, oxybuprocaine, proxymetacaine, tetracaine.
Which anaesthetic is less stingy?
Proxymetacaine but has to be stored in the fridge
Why is time recorded with IOP?
Slight oedema of cornea in morning - raised pressure
What normal variations occur in IOP?
Stress, contraction of extra ocular muscles, squeezing lids, patient supine, tight collar, arterial pulsation, accommodation
What should you do if corneal astigmatism is greater than 3?
Place probe axis at 43 degrees to flattest meridian.
When would you refer?
> 21mmHg
>5mmHg asymmetry
How would you detect cells and flare?
Conical beam 2x2mm light source at 46-60 degrees, bright light on pupil, oscillate light source
