Talk:Ocular tonometry

Comments

The section on pneumotonometry is not very clear. Although air-puff tonometers are sometimes called pneumotonometers, that is not generally considered the correct terminology. A pneumotonometer is a contact device. Pneumotonometers are capable of continuous display of the intraocular pressure over time. The Paradigm Ocular Blood Flow Analyzer is an example of a pneumotonometer that I'm familiar with. A non-contact tonometer on the other hand uses an air puff to obtain a single reading. These devices are not capable of continuous display of IOP over time. Examples of a modern non-contact tonometers include the Reichert AT555 or the Nidek NT4000. Non-contact tonometers certainly have their place in both clinical practice and in research. It is unfortunate that a biased attitude towards non-contact tonometers persists in ophthalmology, but that's another story. —Preceding unsigned comment added by 24.129.101.179 (talk) 03:10, 24 September 2007 (UTC)

Rebound Tonometry

Does this sound like a sales pitch to you, or is it just me? Maybe this section needs to be edited to bring it up to Wiki standards. Jedwards01 (talk) 02:43, 28 October 2008 (UTC)

I concur, placed the "advert" tag in the most blatant section. --Janke | Talk 21:44, 4 March 2009 (UTC)

I've cleaned up the biased statements regarding the iCare and Diatron tonometers. I'm afraid that some edits to the section on Diatron were reverted. I've changed these back. I note that a previous editor cited a number of posters suggesting the device was reliable. I have been unable to verify most of these with the exception of the paper by Lam et al which again concludes that "this eyelid tonometer does not provide good agreement with GAT (Goldmann Applanation Tonometry)" Nernst (talk) 21:48, 21 April 2009 (UTC)

Diatron Tonometer

Previous edits which suggested that the diatron was a phosphene tonometer have been corrected. Many thanks for highlighting the error. Presumably the Diatron is a variant of the TGDc-01. However, both the phosphene and TGDc-01 tonometers still need to be proven and published data on their reliability and clinical utility is skeptical to say the least. Further changes to this section should really be discussed on this page before edits are made. Nernst (talk) 01:11, 26 April 2009 (UTC)

Further edits on the Diatron tonometer should be discussed. The repeated removal of published peer reviewed evidence critizing the device is troubling Nernst (talk) 02:09, 17 January 2011 (UTC)

OCT Tonometry

I'm curious about this part of the article. I couldn't find any info on OCT Tonometry in internet except this part here. Could author of this part provide some references?? —Preceding unsigned comment added by 158.75.4.202 (talk) 13:30, 16 March 2011 (UTC)

Sonic Tonometry

Blinking Reflex

I think that it's important to note that most of the contact tonometry methods – and even the non-contact tonometry methods have a simple drawback (unless the eye is numbed by drops). They evoke the blinking reflex when contact is made with the eye (even the rapid application of a “puff of air” causes people to blink, with the potential that their lashes can be made to make contact with their Sclera, or worse). Use of (hopefully more subtle) vibrations might circumvent this reflex. Of course, the below does NOT work IF even a sensitive laser/LED vibration detection kit cannot determine how the eye responds to a vibration stimulus (due to the eye dampening any vibration to such an extent that even sensitive lasers cannot detect the vibration – though this is unlikely).

Sonic Tonometry

There is at least one journal article that mentions Sonic Tonometry, which, presumably, could use something akin to a directed speaker and directional microphone to see how the eye responds to either vibrations which are made to occur close to the eye (say by a vibrating unit that is left on the Eye LID, which would cause no real discomfort whatsoever, and would not evoke a blinking reflex). A system would simply output certain sounds (groups of pulsating frequencies over varying bandwidths if necessary) and then determine how the eye is responding to those vibrations. Alternatively, instead of a microphone (since hearing the “sound of the eye”'s response to the vibrations would potentially be difficult due to potential dampening effect of the eye to sound), one might use either a LED or a laser to determine the eye's vibration. This would presumably reveal a certain amount of information about the eye's pressure, and potentially something about its internal structure (though this would be convoluted by the structure of the surrounding tissue, which is why a laser/LED used to measure the eye's actual vibrations – potentially even it's internal vibrations in the case of a laser/LED – would likely be necessary to determine the eye's actual “frequency response curve”. It is not too difficult to imagine that the eye's “frequency response curve” could also be determined as the patient looks in differing directions. Admittedly,

A Google search for “sonic tonometry” yields the following link at this current time of editing : http://brain.berkeley.edu/pub/1963%20July%20A%20Report%20on%20Mackay-Marg%20Tonometry.pdf Though it mentions nothing of the technical details involved. In practice, a researcher would probably take an empirical approach (use the other techniques to determine the pressure and see how/if Sonic tonometry correlates with the other methods.

There is clearly much more that could be said...

AnInformedDude (talk) 23:49, 18 August 2012 (UTC)

Calculation of intraocular pressure (IOP)

I have not searched all of the articles to which the wiki refers BUT it does seem as if information on how, experimentally, one determines the IOP from actual measurements involving instruments used for gauging IOP is absent. One imagines in that many of these cases, the calculation procedure is automated (say for non-contact tonometry) – but are there any online sources showing diagrams of how measurements from each of these standardised instruments can be used to calculate the IOP? What would be useful is a simple formula indicating how to get from the measurements to the pressure, perhaps with an online (java?) calculator which might be used by Opticians to check their calculations.

This brings me onto the next question ….

Is Ocular tonometry as standardised and established as the article makes out?

Are each of the instruments (and the manufacturers for them) bound by industry standards? Obviously the answer should be yes, but there may be regional variations, or differences, etc... - but what is the relevant authority which sets the relevant standards? AnInformedDude (talk) 00:56, 19 August 2012 (UTC)

Tonometry calculations

It is often difficult to accurately measure biological parameters and IOP is no exception, in part because of the wide normal variation within and between individuals. As each method is different, the calculations required will depend on the mechanism. There are some studies which compare methods to the gold standard which is an intracameral (in the eye) pressure transducer. These studes are normally performed during cataract surgery when you're already inserting instuments in to the eye. I'm pretty sure there is an ISO standard but don't know the number. For Goldmann tonometry (the clinical gold standard), you would need to consult the original paper from the 1950s. Briefly, Goldmann contented that when an area of 3.05mm was flattened, then the meniscal forces of the tear film were equivalent to those of corneal rigidity (cancelling each other out) so that the pressure could be inferred by the force applied from a calibrated adjustable tension spring. Current Goldmann tonometers all have a calibration bar that can be used to check the forces they apply. Hope thats helpful.Nernst (talk) 21:43, 8 December 2012 (UTC)

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What history, and origin of name

Who named [ocular] tonometry/tonometer ? Confusion with the [audio] tonometer (an array of tuning forks) invented 1834 by Johann Heinrich Scheibler. - Rod57 (talk) 09:44, 1 October 2016 (UTC)

Calibration or rather a configuration?

The first paragraph states "Most tonometers are calibrated to measure pressure in millimeters of mercury". But I would think the calibration takes place in a way where the choice of unit of pressure doesn't matter, and some factor is just applied later to ensure you can read the results of measurements in whatever unit you want. So shouldn't the text rather be along the lines of "Most tonometers are configured to output the measured pressure in millimeters of mercury"? Martinording (talk) 15:28, 15 November 2018 (UTC)

Puff patient informing procedures

Mention if the operator should

• tell, or
• not tell

the patient to expect a puff of air, that they certainly never expected, and which could be quite frightening. Jidanni (talk) 15:39, 25 September 2020 (UTC)