For low vision specialists and those who consult them
Good news about visual impairment in type I diabetes
October 6, 2009Posted by on
There is a paper in this month’s Ophthalmology journal which looks at changes in the proportion of people with type I diabetes who have visual impairment who had an onset of type I diabetes mellitus in the 1960s, 1970s, 1980s, 1990s, or early 2000s.
About 10% of the people they examined with type I diabetes had some visual impairment (defined as being a visual acuity of less than 20/40 (6/12 – about driving standard in most countries), with about 4% having a visual acuity of less than 20/200 (6/60 – being able to see the top letter only on a normal opticians sight chart). Unsurpisingly, they found that the longer someone has diabetes for, the more likely they are to have visual impairment, although this was a fairly small effect.
The good news is that it appears people who are diagnosed with type I diabetes more recently are less likely to become visually impaired than those who were diagnosed in the past. This effect is thought to be due to differences in the treatment offered in the eye clinic (guidelines for laser photocoagulation treatment was only routinely introduced in the 80s) and improvements in diabetes treatment (such as home blood sugar monitoring).
There are a couple of notable limitations of this study: using visual acuity only is a fairly crude way of defining visual impairment, and as with all studies like this the most visually impaired people may not have been identified as they may not have attended all of their follow-up visits. However, this is a large and well conducted study which gives us some encouraging news. As the population ages and most causes of impaired vision are becoming more prevalent, it is encouraging to see a trend in the opposite direction for people with diabetes.