Low Vision News

For low vision specialists and those who consult them

Monthly Archives: September 2010

Envision 2010 – Research overview

Here is the first of my reports from Envision 2010, concentrating on the research sessions.

Envision has really increased the profile of its research sessions recently and this is reflected in the number of people who were presenting new findings at this meeting. Although the organisers hope that there will be overlap between clinical and research sessions at the meeting, in my experience most of my academic colleagues spent 90% of the conference in the research stream with only occasional forays into the more clinical sessions.

The session I most enjoyed was the discussion on cortical reorganisation in macular degeneration. This session, moderated by Gordon Legge, included people with very different views on the extent to which the primary visual cortex changes in macular disease. Chris Baker from NIH (and formerly the Kanwisher lab in Boston) opened proceedings by presenting functional MRI data showing that the lesion projection zone in primary visual cortex did show activation in people with advanced macular disease. Another speaker, Tony Morland from the University of York (UK), showed that this did not occur in the cohort of people he studied, and presented some possible explanations for the cortical activity measured by other groups. The remaining speakers maintained the high level of the presentations and debate was lively throughout the session.

Other research sessions I particularly liked were the discussion on perceptual filling-in chaired by Walter Wittich from Montreal; the reading session moderated by Don Fletcher; and the Quality of Life session chaired by Bob Massof.

The most interesting new data I saw were those presented by Ava Bittner who looked at variability in quality of life experienced by people with retinitis pigmentosa. I also enjoyed the data which Don Fletcher presented on the perception of scotomas by people with macular disease: he showed that only 1 of 108 people perceived their scotoma as a black portion in the centre of their vision (and this one person only noticed it when first waking up before moving her eyes). It really is time people stopped using the NIH picture of AMD as an example of this condition.

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Envision 2010 preview

There seem to be a large number of low vision conferences coming up in the next few months, including Vision 2011 in Kuala Lumpur next February (the largest low vision conference in the world, held every three years). However, I’m still looking forward to Envision this week.

Regular readers of the blog will know I enjoyed Envision last year (see my report here). For me as a someone who divides my time between clinical and scientific work it’s a nice mix of these two disciplines. Whilst the scientific sessions aren’t as likely to present breaking research news on gene therapy trials as a conference like ARVO, the scientific programme has certainly improved in the last few years and is now fairly strong.

I am particularly looking forward to the scientific session on Filling-In (I am speaking in this session, but am looking forward to hearing the other speakers – I’m not being egocentric!). Other scientific sessions which catch my eye are the session on Cortical Reorganisation in Macular Disease chaired by Gordon Legge; and the session on Retinitis Pigmentosa chaired by Olga Overbury, which discusses sleep disorders and emotional aspects of RP.

The clinical sessions which stand out for me include a session on Vision Rehabilitation in Glaucoma led by Mary-Lou Jackson, as I think glaucoma is an often overlooked disease in low vision clinics. The “Clinical dilemmas in visual impairment” event on Friday morning also sounds very interesting.

I’m looking forward to finally seeing the “Going Blind” movie as well.

Envision is a very ‘connected’ meeting – you can follow it on Twitter @envisionconf and you can of course read my report here next week. I hope to see some of you in San Antonio!

Lighting for reading with low vision: The type doesn’t matter!

I received an email from the Macular Disease Support this week advertising a new lamp for people with macular disease to use when reading. Apparently it’s the result of “10 years research” and is “very affordable” (although at $140 +$20 shipping I’m not so sure).

Apparently this light “meets all requirements for best vision” and the advert links to a pretty picture of text shown under different types of light. The print under this light does indeed look clear. However, no careful scientific analysis of reading with macular disease has found any effect of lighting type on reading performance (see, for example, this paper by Frank Eperjesi). What is known is that many people with low vision have far poorer light at home than is available in low vision clinics (see this classic paper.

The message which we tell people time and time again in the low vision clinic is: the important thing isn’t the light itself, it’s where you position it (as close to the task as possible, ideally shining from over your shoulder). If someone has $160 spare to spend on lights – and not everyone with macular disease will have this disposable income – they would be far better spending it on 5 lamps which can be moved near to the task in each room of the house (one in the kitchen for recipes and food packets; one in the bedroom for reading at night, and so on).

I am sure some people will prefer the white LED in this light to a compact fluorescent or tungsten bulb, but there is no evidence that people with MD will systematically prefer this light. I have nothing against this lamp design – indeed it looks quite pretty – but wish that people wouldn’t encourage people to buy an expensive product based on their own experience rather than on scientific evidence.

Different parts of the retina are used for different tasks

I suppose there’s no point in having a blog if you don’t occasionally use it for self-promotion, so here’s a link to a paper we have just had accepted in Investigative Ophthalmology and Visual Science.

In it, we asked people with macular disease to observe a point target, and used the MP-1 microperimeter to determine which part of the retina people used to do this. We then asked the same people to look at some words which appeared on the same screen. By using some quite advanced statisics, we compared whether the same part of retina was used for both tasks.

We found that all of our subjects used different parts of the retina for these two tasks. Often they were not very far apart, but it was statistically clear that they performed these tasks differently.

Why does this matter? Well, it teaches us a little about eccentric viewing in macular disease, and shows that people don’t necessarily do the same thing when looking at a word as when they look at a target. It means that we can’t really assess how well people use eccentric viewing if we just ask them to look at a light and check which bit of retina they use for that, for example. It also shows that the MP-1 microperimeter can be used for fixation analysis in this way.

Any comments welcomed!