Low Vision News

For low vision specialists and those who consult them

Monthly Archives: June 2009

We shouldn’t overlook conditions outside the ‘big three’ causes of low vision

I had an interesting message from Heather Kirkwood in response to my blog post on albinism last week regarding Hermansky-Pudlak syndrome, a condition where albinism is associated with bleeding disorders and pulmonary disease. Whilst this condition is rare (apart from in Puerto Rico) Heather emphasised “just because it is rare doesn’t mean it shouldn’t be overlooked.”

This led me to think that nearly all visual impairment research has studied the effects of the “big three” conditions: Macular disease; Glaucoma and Retinitis Pigmentosa. This doesn’t help those with conditions which affect vision in different ways: even relatively common conditions like diabetic retinopathy, albinism, and corneal dystrophy are rarely studied in low vision research labs.

I am as guilty of this as any of my colleagues: all of my published research to date has been on macular disease. It is clearly important to improve our understanding of a condition which causes severe visual impairment in 1 in 11 people over the age of 75, but it is no less important to further our knowledge of diseases which affect 1 in 1000, or 1 in 1000000 people.

With a finite pool of people working in low vision rehabilitation, and a limited pot of research money for all of us, I think it is inevitable that the most common conditions will be studied more than other causes of low vision. However when I next come to plan a project and apply for research funding I will bear Heather’s comments in mind before writing another grant starting “Age-related macular disease is the leading cause of legal blindness in Europe and North America”. I urge my colleagues to do the same.

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Sony Reader: a missed opportunity for low vision users

My PhD student and I had a play with a Sony Reader electronic book yesterday to see how useful it could be for low vision users. The answer: not very.

Although it has a text zoom feature, on their supplied ebooks the maximum text size is about 0.7logMAR. Given that you need an acuity reserve of at least 2x to read fluently, this means that you need 0.3logMAR (6/12; 20/40) or better to use it.

Maximum contrast is also poor: peak Michelson contrast is 60% which again means that the contrast reserve will be insufficient for most low vision users.

We did find one workaround to get larger print size (convert a document to PDF in large print, then put that into the Reader) but that’s inelegant.

This is a real missed opportunity for Sony: more zoom, reversed contrast and more control over text presentation would be simple to develop and would really expand the use of the Reader for hundreds of thousands of visually impaired people. Several of my patients have asked about electronic books and whether I would recommend them. Whilst I have yet to show any patients the system to see what they think, I’d be surprised if they end up liking it.

I’ve not yet seen an Amazon Kindle but am in the USA next week and will see if I can look at one. I know that, unlike the Sony system, the Kindle has text-to-speech so it’s at least made some effort to embrace users with poor vision.

Feel free to comment if you have any experience with any of these devices for people with poor vision.

Some thoughts on Albinism

I read the review paper on Albinism by Gail Summers in the June 2009 Optometry and Vision Science (link) with interest. When I started working in low vision 11 years ago people with albinism were very interested in knowing whether they had tyrosinase positive or tyrosinase negative albinism: it’s good to be refreshed about the more accepted classifications of OCA1 – 4.

I have always felt that surgery for nystagmus is a bit of a drastic approach and was interested to learn that only 50% of people having had extraocular muscle surgery had an improvement in visual acuity, and those that did only increased by 1 line. Anecdotally, the people I have seen with albinism in the low vision clinic tend to do extremely well at school and to enter high-powered professions: I can’t think that a 1-line VA improvement would make much difference to quality of life in this group of people.

One slight criticism I have of the review paper is that reading speed wasn’t discussed. My impression is that children with albinism read more quickly than would be expected given their visual acuity and contrast sensitivity and I would have been interested in seeing a review of functional performance of people with albinism compared to other causes of visual impairment. Maybe I should write that myself…

Welcome to Low Vision News

Welcome to Low Vision News

This is a new service which will provide a summary of what’s new in Low Vision Research and Rehabilitation.  It is aimed at all of those who work in the low vision rehabilitation community: Optometrists, Researchers, Ophthalmologists, Occupational Therapists, Rehab workers, Teachers of the Visually Impaired and so on.  It is also written with the person with low vision in mind.

The primary aim of this blog is to summarise some of the recent research news relevant to the low Vision Rehabilitation community.  I will also cover conferences, new product launches, and general news of interest.

I am an academic optometrist with an interest in low vision rehab and research.  I have no commercial interest in any companies or services allied to low vision and this blog will be completely impartial.  I am based in London, UK, but hope that the blog will be applicable to all of my colleagues globally.

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