Questions that arise in modelling of new or existing SNOMED concepts
Space shortcuts
Page tree
Overview
Content Tools
Apps
Copyright © 2025 SNOMED International. All Rights Reserved - Privacy Policy - Cookie Settings
Powered by a free Atlassian Confluence Community License granted to SNOMED International. Evaluate Confluence today.
This Confluence installation runs a Free Gliffy License - Evaluate the Gliffy Confluence Plugin for your Wiki!
- Powered by Atlassian Confluence 7.19.29
- Printed by Atlassian Confluence 7.19.29
- Report a bug
- Atlassian News
17 Comments
Elaine Wooler
I am currently authoring "Ghost cell hypertension" but also looking at the modelling of the existing concept 232088004 |Ghost cell glaucoma (disorder)| which currently is modelled as per the image below.
The description of ghost cell glaucoma in the EGS guidelines states ghost cells occur 1-4 weeks after vitreous haemorrhage and the trabecular meshwork becomes obstructed. So should the FSN of the concept be - Ghost cell glaucoma following vitreous haemorrhage (disorder). I can then model this appropriately as AFTER a 31341008 |Vitreous hemorrhage (disorder)| and also model the obstruction of the TM. Or can haemorrhage in other areas have the same result so - Ghost cell glaucoma following intraocular haemorrhage (disorder)?
The same modelling would apply to Ghost cell hypertension though the hypertension would also be modelled.
Ian Rodrigues
Thanks Elaine Wooler I believe that although the commonest cause is after a vitreous haemorrhage, it can occur following any intraocular haemorrhage.
I think "Ghost cell ocular hypertension" would work (rather than "Ghost cell hypertension").
Thanks!
Elaine Wooler
Question regarding causality for the following new concepts:
Is there a causal link in both concepts or just the ocular hypertension? The requested descriptions seem to indicate only a causal link for ocular hypertension but checking on this.
Is the ocular hypertension always post-surgery (we term this as due to and following)?
Many thanks as this impacts modelling.
Sally Baxter
Thanks Elaine Wooler I believe it would be a causal link for both concepts. Ocular hypertension suggests that there is a rise in intraocular pressure after surgery, and the glaucoma term goes a step further to suggest optic nerve damage. For your second question, yes, for this concept it would be post-surgery. Of course, there are patients who have ocular hypertension prior to surgery, but we would not use this particular concept to code that, since in this case I believe we are specifically delineating those who develop ocular hypertension "due to and following" ocular surgery. Anybody else (like Ian Rodrigues or Anthony Khawaja ), please chime in if you disagree, particularly since I know you both were more involved in the diagnosis/condition code revamp efforts.
Ian Rodrigues
Thanks Elaine Wooler and Sally Baxter I think its important that they both use the same wording - so either "Glaucoma/Ocular Hypertension following ocular surgery" or "Glaucoma/Ocular hypertension due to ocular surgery"
- if we want to emphasise a causal link then perhaps "due to" would be better (accepting that causation can never be 100% certain)
- if we want to say the OHT/glaucoma are just associated with ocualr surgery then "following" or "after" would be ok
I think both options would suffice to cover scenarios of OHT/glaucoma in both the early and last post-op time frames following any type of ocular surgery,
Elaine Wooler
Thanks Sally Baxter and Ian Rodrigues The best solution seems to be "due to and following" based on your comments to represent both causality and that this is after ocular surgery. As an example this is what the concept would look like for ocular hypertension:
With both due to and following:
With only following and no causal relationship:
Michael Boland
Is "due to and following" a SNOMED standard approach? It seems redundant to include both "due to" and "following".
Elaine Wooler
Hi Michael Boland Yes - following (modelled with the attribute value 'after') does not imply causation only that the disorder is temporarily related to the surgery. Due and following states there is a causal relationship and states it is explicitly following surgery. Due to alone states causation but does not call out the temporal relationship (during, after). You can find more detailed information at this link Disorder Combination Modeling - SNOMED CT Editorial Guide - SNOMED Confluence (ihtsdotools.org)
Anthony Khawaja
I broadly agree with all that has been said. I would be fine if we left out "following" as some of the glaucoma damage may have occurred during the surgery, but OK to leave it is, as any glaucoma persists and will be following as well!
Ian Rodrigues
Agreed. IMO, I think "Ocular hypertension due to ocular surgery" would work best as it clearly covers the causation, and the temporal relationship (i.e. "following" ) I think is implicitly understood in this situation as the ocular surgery has to precede the glaucoma/OHT in order to cause it.
Elaine Wooler
Thanks, will model these as just 'due to'.
Elaine Wooler
Can I ask about the existing 232090003 |Glaucoma following surgery (disorder)| - this was to be inactivated and replaced with a more precise concept - Glucoma following ocular surgery. Given the ocular hypertension concept is due to ocular surgery should the glaucoma concept also be - Glaucoma due to ocular surgery? Or is the causal link more tenuous here?
Similar to other changes should they also refer to the angle - Open angle glaucoma due to ....., Angle closure glaucoma due to.....
Ian Rodrigues
I agree that "Glaucoma due to ocular surgery" would be good to use to be consistent with the OHT version.
Good point about the angle status Elaine Wooler - it would be an open angle glaucoma so we could call it "open angle glaucoma due to ocular surgery" to avoid any doubt, but am happy either way!
Anthony Khawaja
I'm happy with the proposed "due to" changes.
Elaine Wooler
Further questions please.
The synonyms seem more specific than the FSN. Are these appropriate synonyms?
2. 713457002 |Neovascular glaucoma due to diabetes mellitus (disorder)| is modelled with neovascularisation of the iris so becomes a subtype of 51995000 |Rubeosis iridis (disorder)| - is this correct?
Eric Brown
Elaine Wooler
Thank you - that is much clearer.