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It’s harder to use a magnifier to read a book than a newspaper or magazines, because the book has much longer lines of text. But it’s mostly books that people want to read really fluently.

When we’re considering the fluency-limiting effects of the field of view of a magnifier, it’s not just about the magnifier itself. We also need to consider the line-length of the text. For instance, consider these two texts — same magnification, same field of view, but quite a different reading experience:

Magnified column text
Magnified full page text

With the column text, the only movement needed is a slow downwards scroll to read all text. With the full page-width text, you need to continually scroll side-to-side.

As soon as you reach a point where the full line width doesn’t fit within the field of view, you need to start moving the magnifier side-to-side. Even a small bit of that movement slows reading fluency quite a lot. Fun experiment: put a book under your CCTV and magnify it so the page width just fills the screen width — you’ll find it very easy to read quickly and comfortably, slowly moving the print upwards. Then magnify it just a little more, so there’s about one word missing at the end of each line — you’ll need to keep moving the tray side-to-side, which I’m sure you’ll agree is lot slower and less comfortable.

So it’s very desirable to have (a) a magnifier with as wide a field as possible, and (b) text with as short a line-length as possible.

Books Have the Longest Lines

Where this really bites is that when people are wanting to achieve immersive reading, they are usually reading standard books, which have more words-per-line than just about anything else. Newspaper and magazines use column print, so tend to be easier to read quickly, but those are reading tasks that don’t tend to need such high fluency. Bibles are an example of a text that is in columns that people may want to read fluently for a long period.

Wouldn’t it be great if we could get books converted to column text? It would certainly make it easier to achieve fast-fluent reading using a wider range of the stronger magnifiers.

Well, we can. Kind of. Sort of. We have to cheat.

Shortening the Line

One option that fits the bill is to use a scanning CCTV such as Humanware’s Prodigi.

Humanware Prodigi Desktop

Instead of displaying a directly magnified image of the page, such magnifiers scan the page, extract a text file by OCR (optical character recognition), and display that text file in one continuous column. No matter what magnification is chosen, the user only has to scroll downwards, never side-to-side.

My experience is that the OCR is very good, but not perfect. It has trouble sometimes if the page is not kept quite flat, so we sometimes use a sheet of clear perspex to hold the page flat. The only thing to watch for then is reflections of room lights or windows off the perspex sheet, which can otherwise themselves interfere with the camera’s view.

The other (my favourite!) is to switch to reading eBooks, using an iPad, Kindle or other tablet reader. eBook versions are available of almost any book nowadays, and sometimes it’s even possible to borrow them from your local library.

There are some really great advantages to using a tablet. Like CCTVs, they can display very large text with excellent contrast and brightness, but (unlike CCTVs) they don’t just display the text in a column, they paginate it.

For the Best Reading Experience, Use Pagination

Pagination means the reader doesn’t have to scroll sideways, nor do they have to scroll downwards. When you scroll column text downwards, you have to make a refixation and search up to the left to find the point where you resume reading. If you’ve scrolled too little, you end up re-reading some of the lines you’ve already read. If you’ve scrolled too far, you have to figure that out, scroll back a bit, and then try again.

When the text is paginated, the reader has a consistent location for resuming text. It’s always in the same position, the top left of the page. Refixating to that point is a habit we’ve all learned since we very first learned to read. In this way, the reader can maintain a very high reading fluency, even ir the text is so magnified that there are only a dozen words per page. Rapid page turning generally just involves a light tap on one side of the screen, which is not hard to do.

The other great thing about reading with a tablet is that the reader is able to read wherever they like — instead of having to sit at a desk with a CCTV or reading stand, they can sit in their favourite armchair, at the kitchen table, even lie in bed. This isn’t just a matter of convenience — some of our low vision patients are too frail to sit at a desk, or have no room for a CCTV, or are unable to leave their beds. It’s great to have an option for them.

Tip: Tablets are generally around 10″ screens, although nowadays it’s possible to get some even as large as 13″. That’s not nearly as large as CCTV screens, which are often around 24″. However, remember — it’s not about the size, it’s about the angular subtense. To make the screen ‘bigger’, use a closer working distance. By using a pair of relatively low-powered readers, with some base-in prism to support convergence and preserve binocularity, you can hold the tablet at a closer working distance, which makes a tablet screen seem much larger. For instance, a +4.0D add will make a 10″ tablet at 25cm subtend the same angle as a 20″ CCTV at 50cm. And the effect of pagination means that it’s actually not so important to have such a wide subtense anyway.

If you really do need a wider screen, then it’s useful to remember that apps like iBooks and Kindle can be used to read on a desktop computer. That means you have to go back to a desk, but you get the benefit of paginated text on whatever size screen you like.

Comment: There’s a magnification trick that I’m surprised none of the CCTV manufacturers seem to have picked up on. Bar magnifiers are used to magnify in the vertical direction only (the magnification is only mild, 1.5x – 2x). We recognise words more by the vertical dimensions of the letters than the horizontals, so vertical magnification makes the words more recognisable without increasing line length.

Bar magnifier

It should be simple to include an option for ‘stretched’ magnification on a CCTV, which would allow larger magnification while still fitting the full line-width within the screen. For instance, a paperback book page fits across a 24″ screen at about 5x magnification. But by incorporating a modest 1.5x vertical stretch factor, the vertical magnification would be 7.5x. The price you’d pay is that you fit fewer lines within the screen height, but that’s much easier to deal with — you just need to slide the text upwards a little faster. Importantly, the movement is in just one direction, upwards, rather than constantly switching direction back and forth.


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