Visual Impairment

We have provided newsletter items on visual impairment and reading electronic documents in the past, but it is definitely time for an update. I am particularly aware of this issue as I recently had emergency eye surgery following a sudden partial loss of vision in one eye. This turned out to be a spontaneous detachment of the retina (no obvious cause), which if untreated would result in complete loss of sight in that eye within a few days. The surgery involved two operations, 3 months apart, and the results are thankfully very promising, but it does focus one’s attention on this issue.


I mentioned my experience to my colleague and co-author, a Professor at University College London, who told me that he just been told he was no longer allowed to drive as he had been diagnosed with a progressive form of macular degeneration. This kind of condition typically affects both eyes and results in loss of the ability to read any form of text. So visual impairment can affect anyone, with little or no warning, with major impact on our lives. It is estimated that over 30 million people worldwide have advanced macular degeneration (AMD), the majority being age-related (50 years+), but younger people can be affected by the condition also. And the WHO estimates that there are currently almost 300 million people with partial or severe visual impairment in the world today. The following infographic provides more details on AMD (zoom image to see this full size):


Our publishers regular ask us about support for visual impairment, for which we have provided a number of answers over the years. There are a few central messages:


1. to make documents suitable for reading by those with significant visual impairment affecting both eyes, a great deal of care is needed in designing and delivering documents, and there will be different approaches for end users with differing levels and types of visual impairment. Obviously for some conditions it is sufficient to produce large type versions of printed books, ebooks and other documents. But large type documents require either a larger number of pages in the final document or larger pages, or both. In general (for the purposes of electronic publishing using PDFs) it is better to keep the page size small/the same as standard versions (e.g. A5 or half US Letter), otherwise the displayed version may simply be shrunk to fit the screen, thereby defeating the object of increasing the font size. Of course, for ePUB formatted pulications this is less of an issue because these are designed to support scalable fonts and text reflow.


2. there are special electronic reader devices for various levels of visual impairment – these are generally proprietary and require delivery mechanisms specific to the devices. Although they may include a text-to-speech facility that accepts PDF documents, in general the specific structure of many PDF documents means that they are poorly suited to use on such devices.


There is an excellent website on PDFs and visual impairment here:


3. A “standard” PDF can be displayed using Adobe reader and/or the Mac Preview software with text-to-speech support. If this is the approach a publisher decides to use, then it is strongly recommended that the advice in the link above (on PDF accessibility) is read through carefully and their advice followed as far as possible. Our Javelin readers do not support text-to-speech but our online services do provide PDF to HTML5 conversion, with security for the converted document, and pretty much all modern web browsers include text-to speech support (either as standard or via an add-in).


4. An alternative to a fixed PDF generated in the same manner as a traditional book, is to create a hybrid document. With this approach a mix of text, images and links can be provided in the PDF document, with additional resources provided via web-hosted files. An example might be the provision of web-hosted audio versions of blocks of text and descriptions of images that are linked from the source document.


For example, the paragraph above can be heard rather than read, here:


If you have any questions or experiences on this topic you would like to share, please let us know by replying to this newsletter item. For the latest on copyright law changes that apply to published works and the visually impaired, see the EU press release on this question: