01Jun2011 from 26Jun2010 1620hrs presented at the COS Annual Meeting in Quebec City by Dr Mark Lesk
The full topic of this presentation was: Ocular blood flow in clinical practice: The World Glaucoma Association Consensus Report.
Almost every OBF researcher in the planet answered questions over the internet and then met at ARVO to discuss issues last year. A summary was published in July 2009 by Kugler and answers pretty much any question you might have on blood flow.
The issues that were discussed and summarized in today’s talk included: Can we measure OBF meaningfully, does it contribute to glaucoma, does monitoring OBF change the course, what can we do about it.
OBF measurement techniques
13 clinical techniques discussed and each one has its own strengths and weaknesses. Most techniques are not standardized between centers so there are few multicentre trials. Only LDF looks in the region of the lamina cribrosa where the action is that we are interested in.
Clinical relevance of OBF
Low BP and particularly low OBF are both risk factors for glaucoma as discussed in a prior talk by Dr Leske (no relation.) It is unclear though how these risks apply to our individual patients and also not clear whether modifying these factors changes the course of the disease eg changing time take BP meds so BP doesn’t bottom out overnight.
OBF parameters are impaired in OAG and NTG compared to normals and certain drugs appear to improve OBF. Some of this effect may be IOP dependent. Should measurement of OBF be implemented in clinical practice? Although there is an association between OBF and glaucoma, there is still insufficient data to support its measurement in daily clinical practice. The evidence to support measuring OBF for clinical descision making is lacking. The physiology of OBF regulation needs to be further elucidated.
There are several other ares that are still not fully understood:
- Role of genetic loci that produce vascular dysfunction?
- Relationship between biomechanics, tissue remodeling in glaucoma
- Also need to understand role of CSF pressure in OBF in glaucoma
- Clinical studies are essential to establish the clinical application of OBF measurement in glaucoma
Summary of current consensus:
- Measure meaningfully: sort of
- OBF contributing to glaucoma: yes
- Change course: not proven yet
The Association for Ocular Circulation (AOC) was formed in 2009 in Boston. Efforts to standardize OBF measurement techniques are now underway. This will faciliate multi-centre studies and could eventually lead to measurement of OBF in clinical practice.