Changes in the global estimates for distance-vision loss 1990 – 2015
The VLEG has estimated the number and prevalence of blind and MSVI persons at five-yearly intervals dating back to 1990. These maps provide a visualisation of how these parameters have changed over time.
Changes in the numbers of blind and MSVI persons
The results are summarised in Table 6.
Table 6 – The global number of blind and MSVI persons in five-yearly intervals – 1990 to 2015
|Global number (all ages) affected
|Year||Blind||MSVI||Blind + MSVI|
At first glance this gradual increase may appear as ‘disappointing’. However, over the 25-year period, two very important demographic changes have occurred, both of which would have been expected to give a much greater rise in the absolute number of visually impaired persons:
- The global population has increased by 38% – from 5.3 billion in 1990 to 7.3 billion in 2015.
- The world population has aged and the total population over 50 years old has almost doubled – 878 million in 1990 to 1,640 million in 2015.
The VLEG estimated how many blind and MSVI people one may have expected in 2015, based on 1990 prevalence and modelling for the increased and ageing population. Table 7 below shows what may have been expected in 2015 for both blindness and MSVI compared with the actual numbers.
Table 7 – Actual numbers compared with predicted numbers
|Actual number in 1990||31m||160m|
|Number expected in 2015 if prevalence rates had remained the same as in 1990||57m||286m|
|Actual number in 2015||36m||217m|
|Difference in number of people expected to be blind or MSVI in 2015 compared with actual number in 2015||21m||69m|
|Total difference in number of Blind + MSVI expected compared with actual||90m|
Thus, in the year 2015 there were some 21 million fewer people who were blind and 69 million fewer persons with MSVI than would have been expected – a total of 90 million fewer people experiencing visual impairment.
Changes in prevalence of blind and MSVI persons
The best way to compare changes in prevalence rates over time is to look at age-standardised prevalence rates, as this adjusts for demographic change over the period.
Globally, a decline in age-standardised prevalence was seen over the 25 years, as summarised in Table 8 below.
This decline was seen in all of the 21 GBD regions as shown in the Regional Summaries.
Figure 4 below, which clusters some of the regions together, provides an illustration of the impact of this decline.
Table 8 – The global prevalence (age-standardised, all ages) of blind and MSVI persons in five-yearly intervals – 1990 to 2015
Age-Standardised (all ages)
|Year||Blind||MSVI||Blind + MSVI|
Figure 4 – The decline in age-standardised prevalence of visual impairment between 1990 and 2015 in the world and across the seven Super Regions
The decline in age-standardised prevalence rates, both globally and in each region, over the past 25 years is striking and happens everywhere. One may conjecture that it is due to a number of factors including a decline in poverty levels, a reduction of the incidence of certain conditions or later onset, improved public health measures and eye health service development.
This decline in prevalence, along with 90 million fewer persons who were visually impaired than expected, provides powerful evidence that the fight to eliminate avoidable visual impairment is being won, in at least some countries.
In 2015, there were some 21 million fewer people who were blind and 69 million fewer persons with MSVI than expected
That’s a total
of 90 million
This decline in prevalence, along with 90 million fewer persons who were visually impaired than expected, provides powerful evidence that the fight to eliminate avoidable visual impairment is being won.