Dr Jinapriya starts his talk with some basics defining prevalence (total numbers in population) and incidence (new cases.) He points out that there are lots of prevalence studies from around the world but asks if we can extrapolate and apply to the Canadian population.
The prevalence rates in published reports have a big range and don’t break down the different types of glaucoma. In addition, many of the studies are from the 1980s or even older so they may no longer reflect the current prevalence rates.
What do we know about Canada?
- Large population increase based on immigration
- We’ve now gone from 15% visible minority to 20% in latest census
- We have similarities to Australia and US but still not the same ethnic mix
- Is there a single epidemiological data source for Canada?
We have a Canadian Community Health Survey that assembled data but was based on self reporting of diagnoses. Despite only a few questions related to eyes, and self reported, still 2.3% over 40 yo glaucoma and 3.4% over 50 yo with trend increase prevalence at each age category. These values are higher than US prevalence reported.
Dr Jinapriya’s group therefore did study calling Toronto population to screen those who did not have glaucoma. If any abnormalities, get second visit and if IOP<21 got Diurnal Tension Curve (DTC) to see if IOP higher at other times of the day not detected at the study visits.
They used the Rotterdam Study criteria to define glaucoma eg c/d >0.7 either eye or asymmetry c/d >0.2, etc. Also definitions for probable glaucoma and glaucoma suspect were given. Of 180 ending up being screened, 8 confirmed glaucoma for 4.4% of these patients who were not known to have glaucoma before. This is pilot data with 4.4% glaucoma, 3.9% being OAG.
There are no large population studies published for Canada; we just have this pilot data. Glaucoma population data we have is more fiction than it is fact for now.