How fast should people expect to read with magnifiers?
If a patient isn’t achieving high fluency with a magnifier, is that due to the patient’s vision impairment, or could the limitation be inherent in using the magnifier?
Is it even possible to achieve high fluency with some magnifiers?
I wanted to know what factors might be an inherent part of using a magnifier, as opposed to a limitation due to the user’s vision impairment, so I did an experiment with myself as a subject. Since I have normal vision, any effect on my reading speed would be due to factors inherent in using the magnifier, rather than any vision impairment.
I selected a range of magnifiers, and with each I timed myself reading an entire page of Patrick O’Brian’s Master and Commander — The Letter of Marque. It has about 375 words per page. The magnification with electronic readers was calculated by direct measurement and comparison of letter height. I’ve tabulated the results, listing them roughly in order of increasing magnification. Fast-fluent reading speeds (over 180 wpm) are in green, with darker green for anything over 250 wpm. Slow-fluent (over 120 wpm) is in yellow, while anything slower than that (ie- spot-reading) is in red.
If I can’t read fast with a magnifier, I don’t see how I can expect my patients to read fast with it. We could call my results the Maximum Potential Reading Speed for each magnifier, but I tend to just think of them as the magnifier’s Speed Limit.
The caveat on this is that younger patients keep on confounding my expectations. With so much brain plasticity, sometimes they manage to perform efficiently with magnifiers in a way that I can’t. I think my findings are pretty sound for patients who have older-onset low vision, which makes up the large majority of patients at my LVC. But for younger patients — you have to take them as they come, and not pre-judge too much.
Points of interest:
- Under about 5x magnification, I was able to maintain a high reading rate (above 180 wpm needed for immersive reading) with all the magnifiers I tried. That’s not to say they didn’t slow me down though — I’m a fast reader, and all the magnifiers knocked at least a third off my normal reading speed, other than using the iPhone (small field of view, but highly efficient paginated text), the magnifier lamp (relatively wide field of view, both hands able to hold the book), and the CCTV (fitting the full line length within the screen width, so all I had to do was slowly push the page upwards).
- I thought it was interesting to see that my reading speed when reading aloud was so slow. It didn’t even quite reach the immersive reading speed. This is something we should keep in mind whenever we ask patients to read out text to judge whether they are reading fluently. Even if they sound perfectly fluent, they might still be reading at a level well below their accustomed silent reading speed. If they are stumbling at all then they are going to be below the fast-fluent speed. But if they sound fluent, we still need to check with the patient whether if feels fluent to them.
- Between 5x and 9x, I couldn’t read at a fast-fluent speed with any of the optical magnifiers. Perhaps I could with practise, but I doubt it. I think I already know pretty well how to manage a magnifier. Electronic magnifiers worked much better. In fact, with 5x on the CCTV I was at almost 100%. Notice though how my reading speed dropped markedly as soon as the page width didn’t quite fit in the screen — even that tiny bit of side-to-side movement knocked a third off my reading speed.
- At 10x, reading with the optical magnifiers was really slow and uncomfortable. The CCTV was much better, but the continual side-to-side scrolling precluded fast-fluent reading. Only the Prodigi’s ability to give me a continuous column of text let me achieve an acceptably-fast reading speed. In contrast, reading the text in one continuous line was a much less pleasant experience, and really slowed me down. (It would be perfect if the Prodigi gave the option of paginated text instead of a continuous column — perhaps we might get that in a future software upgrade).
- I really noticed a physical comfort difference between the electronic and optical magnifiers. The stronger optical magnifiers made me feel a bit motion-sick after a while, probably due to the rapid image flow across my field of vision. With the stronger handhelds, it was hard to keep the book and magnifier aligned precisely enough to avoid the print going in and out of focus. With the stand magnifiers it was hard getting the print near the centre of the book in focus, as the base continually banged into the facing page or made it hard to see words at the end of the line where the page bends in towards the spine.
- In contrast, the electronic magnifiers were steady, and I was able to see all of them binocularly and at a comfortable distance, even on the very largest settings.
- The iPad and iPhone were pushed to the max, by bringing them abnormally close. They would be more comfortable at 30 or 40cm, but even 20cm was okay, and there was ample room to fit my hand in to touch the screen. Even though there were only a few lines on the screen at maximum magnification, the pagination format just meant I had to compensate by turning the page more frequently, which was a simple tap on the right side of the screen — that didn’t slow me down much at all. Still, although I haven’t noted it in the table, it only took dropping back to the second or third-highest magnification levels to get me back to full 100% reading speed.
- At 20x, even the continuous column of text displayed by the Prodigi wouldn’t let me read at even a slow-fluent speed. The words are just too large, and I just couldn’t scroll-and-refixate the column fast enough. I suspect that if there was a pagination option the speed might go up to about 140-150.
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