Goldmann tonometer and the Imbert-Fick law

[yzf-r1]

2 questions that nobody here seems certain about.

1. How does the goldmann tonometer take into account the ocular rigidity to ensure that the value one reads is that of the IOP alone?

2. How does the goldmann tonometer take into account the fact that the eye does not fulfil that criteria that the Imbert-Fick law has i.e. the eye is not infinitely thin, perfectly elastic, dry etc etc?

Many Thanks
Y

[John R]

Interesting to note that you have posted this @ monoptica & AOP's forum as well. Wonder where will answer first.

And the result is.....
Have to declare a draw as Optiboard & Monoptica had replies on the same day, sadly Aop has only had 4 views...

[Darryl Meister]

According to Tunnacliffe (Introduction to Visual Optics, ABDO, 1993):

IOP is approximately equal to (tonometer applied force + surface tension - corneal elasticity)/(applanated area)

Tunnacliffe goes on to say that the forces of corneal elasticity and surface tension of the tears balance and cancel each other out when the applanated area has a diameter of 3-4 mm, leaving:

IOP is approximately equal to (tonometer applied force)/(applanated area)

Which should be sufficiently accurate for practical purposes. Hope this helps.

Best regards,
Darryl

[Darris Chambless]

Hey Darryl,

I have a question regarding your reference to tear film. I've used NCT and hate it, the readings are never accurate and were always high because people would tense up when they thought the "puff" was coming. But, my question actually is how much affect would tear film or the movement thereof affect the reading of an NCT? Any idea?

Darris C.

[yzf-r1]

John R said:
Interesting to note that you have posted this @ monoptica & AOP's forum as well. Wonder where will answer first.

And the result is.....
Have to declare a draw as Optiboard & Monoptica had replies on the same day, sadly Aop has only had 4 views...

nice to see that you visit all the boards...long may that be the case!!!!!

[10 Pence Short]

yzf-r1 (if that is your real name),

Two things:-,

1. I'm assuming that because you started these questions on UK boards you're British, but you haven't said your location on this forum. Where are your from Yamaha boy?

2. Why on earth have you named yourself after a motorcycle?

3. If you can't answer the above, what is the meaning of life?