The holy trinity: three papers commonly used to justify the treatment of visual stress in dyslexia

When people are trying to make a case for treating visual stress to ameliorate reading difficulties they frequently cite three papers. For example, this power point file was taken from a lecture given to optometry students by a well known proponent of coloured lenses and overlays. The first three papers cited (listed below)  are said to validate treatment with coloured lenses and overlays. I will be reviewing these in some detail in subsequent posts. Ignoring any issues of cherry picking, taken individually or as a whole these papers do not come close to forming a credible evidence base for the treatment of visual stress in dyslexia.
Another example comes from a publication in the March 2015 issue of the Scandinavian Journal of Occupational Therapy - Using coloured filters to reduce the symptoms of visual stress in children with reading delay. The authors state 'that this type of intervention has been found to ease the discomfort experienced and improve reading accuracy' - citing references 1 and 3 below. Subsequently they claim that randomised controlled trials show that coloured filters can improve reading speed citing reference 2 below.

So, over the next few weeks I will be reviewing these papers in some detail. In my experience they are frequently cited but I suspect some people a only read the title or the abstract or worse still, copy the citation from other papers without going back to basics and critically appraising the text. 
This will be a somewhat dry process but, as ever, the devil lies in the detail. Sometimes those who produce superficially impressive lists of references to back up their claims rely on the fact that most people do not have have time or inclination to carefully read and appraise the original papers.

The first paper is
1.         Wilkins AJ, Evans BJ, Brown JA, Busby AE, Wingfield AE, Jeanes RJ, et al. Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays. Ophthalmic Physiol Opt J Br Coll Ophthalmic Opt Optom. 1994 Oct;14(4):365–70. (pubmed link)

The second
2.         Bouldoukian J, Wilkins AJ, Evans BJW. Randomised controlled trial of the effect of coloured overlays on the rate of reading of people with specific learning difficulties. Ophthalmic Physiol Opt J Br Coll Ophthalmic Opt Optom. 2002 Jan;22(1):55–60. (pubmed link)

And third
3.         Robinson GL, Foreman PJ. Scotopic sensitivity/Irlen syndrome and the use of coloured filters: a long-term placebo controlled and masked study of reading achievement and perception of ability. Percept Mot Skills. 1999 Aug;89(1):83–113. (pubmed link)

You can obtain the first two publications from Arnold Wilkins' web page unfortunately number 3 is hidden behind a pay-wall in a pretty obscure, low impact factor, journal. Most university libraries do not have it.