Hi everyone, I am creating discussion pages for categories of topics arising from our meeting on 3/23/2023. My apologies for the delay in posting; just returned from spring break. I will put the IOP-related ones here, and then a separate one for gonioscopic grading.
Here are some of the intraocular pressure (IOP)-related codes that the group thought would be useful to add to SNOMED (based on survey of glaucoma specialists and discussion at the last meeting):
Maximum IOP
Maximum untreated IOP
Presenting IOP
Target IOP
Laterality: These would apply to each eye (left eye, right eye). Unlike diagnosis codes there isn't a bilateral situation for this one.
Range of Observed Values: In terms of the range of observed values, we expect these to be positive integers.
Associated Units: The associated units would be mm Hg for each value.
Method of tonometry: Another associated code to develop is the ability to denote the method of tonometry used, which is currently not represented completely in SNOMED (there is a code for non-contact tonometry but otherwise the specifications for other forms are lacking). Here is a suggested list for methods of tonometry from one of our group members in the survey that was administered:
Goldman applanation
Rebound (iCare)
Non-contact
Pneumatonometer
Mackay-Marg (Tonopen)
Dynamic contour
Indentation
Tactile
ORA
Elaine Wooler Let me know if additional info is needed. Happy to provide and/or solicit additional info from the group, and of course appreciate everyone's input here. It would be great to advance this toward incorporation into the vocabulary and thanks in advance for your help!
Just so I can understand the distinction between them and not sure what you mean by maximum. For example the definition on 723235005 |Maximum blood pressure (observable entity)| is An aggregated blood pressure that refers to the maximum over multiple cardiac cycles, e.g. over 24 hours
Thanks Elaine Wooler - for maximum IOP, often we will ask patients what their maximum IOP was historically. This helps us assess their ocular history and helps inform our target IOP for their treatment plan. It can be a self-reported value, particularly for new patients presenting for care, where they may have had IOP values recorded at the prior practice but we do not have that information currently in our records. As such, it is usually not secondarily derived based on an array of recorded IOP values in a given EHR. "Maximum untreated IOP" represents their maximum eye pressure while not having any treatment (like medications, lasers, or surgeries). "Maximum IOP" does not have any specification regarding treatment history, although in practice treated IOP should be lower than untreated IOP. Adding Ian Rodrigues and Anthony Khawaja if they have any additional comments, and certainly anyone from the group can comment and add further clarification. Thanks!
Just editing to add that the maximum IOP (or maximum untreated IOP) may not always be strictly patient/self-reported per se. Sometimes it can be physician-reported based on a review of the prior records, either from the same system or records obtained from the system of prior care. The time frame is not over a 24-hour cycle but rather represents the maximum over all preceding time/ entirety of patient history leading up to that point.
A good point. I suppose a DERIVED max IOP would be something that is calculated from other fields. A REPORTED max IOP would be from patient history? We could have a hierarchy here - max IOP, and under that, "patient-reported", "physician reported", "derived from historical measures", "unspecified", or similar?
I've added the concepts for maximum IOP, maximum untreated IOP and target IOP. We don't usually add concepts of the type - Presenting IOP as this not a quality like maximum or target but is evident from the date so information model derived. Would this cause any issues if this were not added?
Actually, I think it is OK to leave out "presenting", as that can be inferred as the original IOP in a series at one centre? Some may argue we want to enter a historic presenting IOP, but we can just enter historic IOPs with their dates. That's my opinion, anyway!
Thanks Sally. Some ORA (Ocular Response Analyzer) comments:
Need to specify if IOPg (Goldmann-correlated IOP) or IOPcc (corneal-compensated IOP), as both are output
The outputs are not integers - the pressures are given to one decimal place
Should we also include the Corvis? I believe that outputs numbers to one decimal place as well, and there is a bIOP for "best" corrected for corneal properties, and a standard NCT one.
Thank you both. So the IOP codes are 'question" codes which will take a value. I would suggest these would be subtypes of 41633001 |Intraocular pressure (observable entity)|. Observable entities in SNOMED are the questions e.g. 315613000 |Target diastolic blood pressure (observable entity)|.
For the methods - these would be procedures in SNOMED. If you could review the 11 concepts under 164729009 |Tonometry (procedure)| and feedback any comments on their current validity and any gaps based on the list you have already provided. I've added these to a shared google sheets document - link below. Please let me know if you have any issues accessing this.
Hi Elaine Wooler I think the subtype framework would work, similar to the target diastolic blood pressure one you shared (but instead being target introacular pressure, as one example).
Thanks for sharing the Google doc on the tonometry concepts. I didn't realize methods of measurement were listed as "procedures", so that is really helpful to know. I added some comments there, and added some terms that are not currently represented (i.e. the gaps), but I think it would be helpful perhaps to also discuss as a group at our next CRG meeting as well.
That Google Doc is very helpful. I added a column with the parent term to make the hierarchy more clear. Interestingly, "non-contact" is a child of the "applanation" procedure (and Schiotz isn't). I also did a quick search for "digital tonometry" in pubmed just to see how often that two-word-phrase is used. It was very rare and slightly more commonly used in cardiology papers talking about measuring pressure in the fingers.
I am working on the tonometry procedures and there was a suggestion to merge 392338001 |Indentation tonometry (procedure)| and 389149000 |Schiotz tonometry (procedure)|. In SNOMED these are also separate devices - 391955007 |Schiotz tonometer (physical object)| and 392340006 |Indentation tonometer (physical object)| So would 389149000 |Schiotz tonometry (procedure)| be a subtype of 392338001 |Indentation tonometry (procedure)| rather than the same thing? Also based on this section IOP and Tonometry - EyeWiki (aao.org)
I agree with Michael. Just circling back a bit - does this influence how we handle the other methods of IOP measurement? E.g. iCare tonometer for Rebound Tonometry (there is another one available now or soon by Reichert). I.e. should we be adding in all devices?
We don't add branded devices so if the iCare tonometer does something specific we would need to have a generic name for the procedure.
I was also looking at 252805009 |Digital tonometry (procedure)| and it was suggested that a synonym be added of Tonometry by palpation. However the concept has an existing synonym - Portable electronic applanation tonometry. Is it best to inactivate this concept and create two new concepts:
Does "digital" in this context mean "using your finger" for palpation (aka tactile)? Or does it mean "not analog or electronic"?
The second synonym of "Portable electronic applanation tonometry" seems wrong (I've never heard any practicing ophthalmologist refer to "digital tonometry" when they didn't mean palpation.)
I would suspect that "Digital tonometry (procedure)" should be retired and that tactile (from the 5/18/23 CRG meeting discussion) should be used instead.
The original concept did not have the ""Portable electronic applanation tonometry" synonym, it was added later in 2003. I can't trace that far back but the original 1995 UK NHS Read code stated only Digital tonometry. So it looks to be an erroneous synonym. I can retire the concept and replace with the tactile version as discussed.
Hi Elaine Wooler I know at one point you had sent us a google doc that showed all the concepts related to this topic that you developed and submitted to SNOMED on our behalf, but for some reason I can't seem to find it. Would you be able to link it here again? So sorry for the inconvenience.
25 Comments
Sally Baxter
Hi everyone, I am creating discussion pages for categories of topics arising from our meeting on 3/23/2023. My apologies for the delay in posting; just returned from spring break. I will put the IOP-related ones here, and then a separate one for gonioscopic grading.
Here are some of the intraocular pressure (IOP)-related codes that the group thought would be useful to add to SNOMED (based on survey of glaucoma specialists and discussion at the last meeting):
Laterality: These would apply to each eye (left eye, right eye). Unlike diagnosis codes there isn't a bilateral situation for this one.
Range of Observed Values: In terms of the range of observed values, we expect these to be positive integers.
Associated Units: The associated units would be mm Hg for each value.
Method of tonometry: Another associated code to develop is the ability to denote the method of tonometry used, which is currently not represented completely in SNOMED (there is a code for non-contact tonometry but otherwise the specifications for other forms are lacking). Here is a suggested list for methods of tonometry from one of our group members in the survey that was administered:
Elaine Wooler Let me know if additional info is needed. Happy to provide and/or solicit additional info from the group, and of course appreciate everyone's input here. It would be great to advance this toward incorporation into the vocabulary and thanks in advance for your help!
Elaine Wooler
Hi Sally Baxter
Could you provide definitions for:
Just so I can understand the distinction between them and not sure what you mean by maximum. For example the definition on 723235005 |Maximum blood pressure (observable entity)| is An aggregated blood pressure that refers to the maximum over multiple cardiac cycles, e.g. over 24 hours
Is there something similar for maximum IOP?
many thanks
Sally Baxter
Thanks Elaine Wooler - for maximum IOP, often we will ask patients what their maximum IOP was historically. This helps us assess their ocular history and helps inform our target IOP for their treatment plan. It can be a self-reported value, particularly for new patients presenting for care, where they may have had IOP values recorded at the prior practice but we do not have that information currently in our records. As such, it is usually not secondarily derived based on an array of recorded IOP values in a given EHR. "Maximum untreated IOP" represents their maximum eye pressure while not having any treatment (like medications, lasers, or surgeries). "Maximum IOP" does not have any specification regarding treatment history, although in practice treated IOP should be lower than untreated IOP. Adding Ian Rodrigues and Anthony Khawaja if they have any additional comments, and certainly anyone from the group can comment and add further clarification. Thanks!
Sally Baxter
Just editing to add that the maximum IOP (or maximum untreated IOP) may not always be strictly patient/self-reported per se. Sometimes it can be physician-reported based on a review of the prior records, either from the same system or records obtained from the system of prior care. The time frame is not over a 24-hour cycle but rather represents the maximum over all preceding time/ entirety of patient history leading up to that point.
Anthony Khawaja
A good point. I suppose a DERIVED max IOP would be something that is calculated from other fields. A REPORTED max IOP would be from patient history? We could have a hierarchy here - max IOP, and under that, "patient-reported", "physician reported", "derived from historical measures", "unspecified", or similar?
Elaine Wooler
I've added the concepts for maximum IOP, maximum untreated IOP and target IOP. We don't usually add concepts of the type - Presenting IOP as this not a quality like maximum or target but is evident from the date so information model derived. Would this cause any issues if this were not added?
Anthony Khawaja
Actually, I think it is OK to leave out "presenting", as that can be inferred as the original IOP in a series at one centre? Some may argue we want to enter a historic presenting IOP, but we can just enter historic IOPs with their dates. That's my opinion, anyway!
Ian Rodrigues
I agree. As long as we have target IOP and maximum untreated IOP I'm happy!
Sally Baxter
Agree as well. This is great news that maximum IOP and target IOP have been added. thanks so much Elaine Wooler !!
Anthony Khawaja
Thanks Sally. Some ORA (Ocular Response Analyzer) comments:
Should we also include the Corvis? I believe that outputs numbers to one decimal place as well, and there is a bIOP for "best" corrected for corneal properties, and a standard NCT one.
Sally Baxter
Thanks Anthony Khawaja I am not super familiar with ORA so this is very helpful! Seems reasonable to include Corvis as well.
Elaine Wooler
Thank you both. So the IOP codes are 'question" codes which will take a value. I would suggest these would be subtypes of 41633001 |Intraocular pressure (observable entity)|. Observable entities in SNOMED are the questions e.g. 315613000 |Target diastolic blood pressure (observable entity)|.
For the methods - these would be procedures in SNOMED. If you could review the 11 concepts under 164729009 |Tonometry (procedure)| and feedback any comments on their current validity and any gaps based on the list you have already provided. I've added these to a shared google sheets document - link below. Please let me know if you have any issues accessing this.
https://docs.google.com/spreadsheets/d/1OJTIkiyXZPSvroCuPpRvaLkiazrzOE_3/edit?usp=sharing&ouid=117788045448290102226&rtpof=true&sd=true
Sally Baxter
Hi Elaine Wooler I think the subtype framework would work, similar to the target diastolic blood pressure one you shared (but instead being target introacular pressure, as one example).
Thanks for sharing the Google doc on the tonometry concepts. I didn't realize methods of measurement were listed as "procedures", so that is really helpful to know. I added some comments there, and added some terms that are not currently represented (i.e. the gaps), but I think it would be helpful perhaps to also discuss as a group at our next CRG meeting as well.
Eric Brown
That Google Doc is very helpful. I added a column with the parent term to make the hierarchy more clear. Interestingly, "non-contact" is a child of the "applanation" procedure (and Schiotz isn't). I also did a quick search for "digital tonometry" in pubmed just to see how often that two-word-phrase is used. It was very rare and slightly more commonly used in cardiology papers talking about measuring pressure in the fingers.
Ian Rodrigues
This is great. From my point of view target IOP and maximum untreated IOP would be really useful to have.
Have also added a column on the spreadsheet with my comments.
Sally Baxter
Modified names (from 5/18/23 CRG meeting):
(can do mapping from generic name to brand names as part of ETL)
(also need Corvis represented; generic representation TBD - maybe video deformation tonometry... still in progress)
Elaine Wooler
I am working on the tonometry procedures and there was a suggestion to merge 392338001 |Indentation tonometry (procedure)| and 389149000 |Schiotz tonometry (procedure)|. In SNOMED these are also separate devices - 391955007 |Schiotz tonometer (physical object)| and 392340006 |Indentation tonometer (physical object)| So would 389149000 |Schiotz tonometry (procedure)| be a subtype of 392338001 |Indentation tonometry (procedure)| rather than the same thing? Also based on this section IOP and Tonometry - EyeWiki (aao.org)
Michael Boland
I agree Schiotz is a specific example of Indentation tonometry, so Schiotz could either be a subtype or a synonym for indentation.
Anthony Khawaja
I agree with Michael. Just circling back a bit - does this influence how we handle the other methods of IOP measurement? E.g. iCare tonometer for Rebound Tonometry (there is another one available now or soon by Reichert). I.e. should we be adding in all devices?
Elaine Wooler
We don't add branded devices so if the iCare tonometer does something specific we would need to have a generic name for the procedure.
I was also looking at 252805009 |Digital tonometry (procedure)| and it was suggested that a synonym be added of Tonometry by palpation. However the concept has an existing synonym - Portable electronic applanation tonometry. Is it best to inactivate this concept and create two new concepts:
Eric Brown
Does "digital" in this context mean "using your finger" for palpation (aka tactile)? Or does it mean "not analog or electronic"?
The second synonym of "Portable electronic applanation tonometry" seems wrong (I've never heard any practicing ophthalmologist refer to "digital tonometry" when they didn't mean palpation.)
I would suspect that "Digital tonometry (procedure)" should be retired and that tactile (from the 5/18/23 CRG meeting discussion) should be used instead.
Elaine Wooler
The original concept did not have the ""Portable electronic applanation tonometry" synonym, it was added later in 2003. I can't trace that far back but the original 1995 UK NHS Read code stated only Digital tonometry. So it looks to be an erroneous synonym. I can retire the concept and replace with the tactile version as discussed.
Sally Baxter
Thanks Elaine Wooler I agree with Eric Brown ... we are meaning palpation/tactile. Agree the electronic applanation would be an erroneous synonym.
Sally Baxter
Hi Elaine Wooler I know at one point you had sent us a google doc that showed all the concepts related to this topic that you developed and submitted to SNOMED on our behalf, but for some reason I can't seem to find it. Would you be able to link it here again? So sorry for the inconvenience.
Elaine Wooler
Hi Sally Baxter Not a problem, you can find the link in the documentation section - Documentation - Eye Care CRG
I'm also now adding the lateralised diagnoses which should be ready for release in December.