IOP-based patient stratification has value; NTG or POAG debate continues

San Francisco - Normal-tension glaucoma (NTG) is likely primary open-angle glaucoma (POAG) with a lower baseline IOP. However, it is probably worthwhile to continue to draw a distinction between these two entities because it provides an opportunity for identifying risk factors that may have varying influence depending on the level of IOP, said Anne L. Coleman, MD, PhD, the Frances and Ray Stark Professor of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles.

As an example of the potential to determine unique risk factors depending on IOP, Dr. Coleman reviewed the findings from the Collaborative Normal Tension Glaucoma Study (CNTGS) and the Early Manifest Glaucoma Trial (EMGT). Disc hemorrhage was the only progression risk factor that was common to the two studies. Other risk factors identified in the CNTGS were migraines and female gender, while in the EMGT, elevated IOP, bilateral disease, pseudoexfoliation, and older age were also associated with higher risk.

“It is important to realize that for all diseases, there is a continuum from health to sickness, and that it is often difficult to make sharp distinctions in disease classifications. Where disease is defined along this continuum can be based on a variety of criteria, but any classification should be useful and clinically relevant,” Dr. Coleman said.