For low vision specialists and those who consult them
Monthly Archives: October 2009
October 23, 2009Posted by on
The most recent issue of Ophthalmic Epidemiology has an interesting paper by Spencer and colleagues on access to healthcare by people with visual impairment and blindness in the USA.
It shows quite elegantly that those who are visually impaired have more problems in accessing health care than those with good vision: 8.5% of those with visual impairment reported being unable to access necessary healthcare, compared to 4.6% of those who were legally blind, and 2.6% of those with good vision. Key barriers identified by those with visual impairment were cost, transportation, and insurance issues. Those who were legally blind experienced fewer difficulties than those with visual impairment (perhaps due to the extra benefits which blind certification entitles you to, such as supplementary security income and social security disability income). Legally blind people were, shockingly, more likely to be refused services.
This study was well conducted and corrected for differences in socio-economic status of those who are visually impaired (in this group, the visually impaired were more likely to be older, female, and unmarried than the group with good vision, for example). The study also has impressive statistical power: as a clinical researcher, I am always amazed when I see the number of subjects in most epidemiology papers (over 40,000 in this case).
As the US healthcare debate rumbles on, it is important to address problems with access to health services experienced by those with visual impairment. However, this study also raises wider problems with healthcare access – over 2.5% of people with good vision also report they are unable to get necessary medical care.
October 20, 2009Posted by on
There is a nice trio of papers in the current issue of the journal Eye which review the current state of research in gene therapy, stem cell therapy, and retinal prostheses. They are all well written and offer a balanced view of the likelihood of each of these techniques being useful for people with retinal disease.
The gene therapy paper, by Jim Bainbridge of the Moorfields/UCL Institute of Ophthalmology centre, summarises the principles behind gene therapy and briefly describes the results of the Moorfields, University of Pennsylvania and Childrens Hospital of Philadelphia trials. These trials were all for people with a rare but well understood degeneration called Leber’s Congenital Amaurosis. Each of the groups report improvement on some measures of function, although not visual acuity. Bainbridge suggests that the treatment will be most effective when applied very early in the disease process when there are still a large number of cells which can be “rescued”. He also claims it will be easier to treat diseases which affect the retinal pigment epithelium than the photoreceptors, so for example Stargardt disease will be less easy to treat with this technique.
The stem cell paper is by Johnson and colleagues from Cambridge. They describe some of their laboratory work on animals with induced glaucoma. Whilst these results are encouraging there are many technical issues which need to be addressed, which they discuss. Of course there are also very large ethical and regulatory issues with stem cell therapy, particularly for embryonically derived stem cells.
The final paper summarises some of the work on retinal prosthesis (“artificial retinas” implanted into people with no vision from diseases such as retinitis pigmentosa. There are several different technologies which are described in this paper, and the authors state that three different commercial products are likely to appear by the end of 2010 (from Second Sight, Intelligent Medical Implants and from Retina Implant). They also describe a very interesting approach used by a group at Imperial College, London, where viral engineering can make retinal ganglion cells or bipolar cells light sensitive (i.e. which can make nerve cells act like photoreceptors). This sounds very exciting, although no in vivo animal trials of this technology have yet been performed, let alone human trials.
Together the three articles provide an interesting overview of cutting edge science at present. I imagine that in the next 5-10 years all of these methods will be used more and more for people with eye disease. I wouldn’t like to guess which will end up being the most successful approach, but think we should all watch these emerging fields of science with interest.
October 14, 2009Posted by on
There has been much speculation in the British newspapers about Prime Minister Gordon Brown’s eyesight and how it may affect his ability to govern (see for example, this article in the Observer, my favourite British newspaper).
I find this type of reporting distasteful. The implication that someone with visual impairment is unable to perform an important job is flawed at best and offensive at worst. All low vision specialists with a few years experience will have met people with very poor vision successfully performing high pressure jobs (for example, I have been consulted by senior academics, lawyers, investment bankers, journalists, lawyers, and a television producer). Indeed, the UK’s former home secretary David Blunkett has no light perception in either eye (and gave one of the best presentations at the Vision 2005 conference in London).
If Gordon Brown was a pilot or a bus driver then it would be in the public interest to know if his vision fell below a certain standard and he was continuing to work. However I fail to see why poor vision would be of any relevance to someone’s ability to be a politician, particularly one in central government who will have dozens of aides who could act as readers if necessary. It also really sends the wrong message to young people with visual impairment: if your eyesight gets worse you can’t run for election to parliament.
Incidentally, from this report it sounds unlikely that Mr Brown’s vision does fall into any of the definitions of low vision: meaning that this story really is a lot of fuss about nothing. I’d rather read some perceptive reporting on the Prime Minister’s actions rather than speculation about his vision.
Sorry this is a bit of a subjective rant rather than a research synopsis – I promise I’ll go back to science for the next post.
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.