Glaucoma/Ocular hypertension concept authoring questions

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.

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!

Question regarding causality for the following new concepts:

• Glaucoma following ocular surgery (disorder)
• Ocular hypertension due to ocular surgery (disorder)

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.

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.

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, 

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:

Is "due to and following" a SNOMED standard approach?  It seems redundant to include both "due to" and "following".

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!

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. 

Thanks, will model these as just 'due to'.

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.....

I'm happy with the proposed "due to" changes.

Further questions please.

1. 232086000 |Neovascular glaucoma (disorder)| has two synonyms:
   1. Rubeotic glaucoma
   2. Secondary angle closure glaucoma with rubeosis

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?