1.1 Introduction



The contents of this site came about as a way to bring together the content of the low vision lectures I’ve delivered over the years, and to expand on them in a way that just isn’t possible in a lecture format. Having them on a website also means that anyone can access them, wherever they are — I hope in particular that they might help practitioners in countries where low vision care isn’t well developed.

My inclination is to be very practical, but in fact there’s a large chunk of this site that is theoretical. Over the years I’ve thought a lot about what seems to work and what doesn’t, and tried to figure out why. The result is a theoretical framework that I find really helps me understand what’s going on, so I’m presenting it here in detail, in the hope that it will help others understand, and perhaps inspire brighter minds than mine to develop it further.

TLDR (Too Long, Didn’t Read) is what all the hip kids use instead of the more formal ‘Executive Summary’. I like to pretend I’m hip, so I’ll use TLDR.

Vision Impairment: It’s Not About the VA.

The first section is a discussion of the nature of pathological vision impairment, particularly as it affects the macula (which makes up the vast bulk of the patients). It’s a mistake to think of a patient with 6/60 (20/200) from AMD in the same category as a patient with 6/60 from refractive error. VA can be very misleading, as many (perhaps most) patients with very impaired vision still have good VA — and yet, it’s still often the only measurement we take in general optometric/ophthalmologic practice, and the main one used in defining legal blindness. Having a clear understanding of visual dysfunction is the foundation of effective vision rehabilitation.

Get used to thinking about low contrast and macular field loss instead of VA.

Bigger, Bolder, Brighter: Gotta Use ’em All.

You shouldn’t think low vision work is just a matter of choosing the right magnification. It’s just as important to know how and when to manipulate illumination and contrast. Sometimes we only need to manipulate one of those parameters, but how do we know which would be most effective? More often we need to work on more than one parameter at the same time if we’re going to get a successful outcome, but how do we tell which combination would work best together?

The second and third sections seek to answer those questions, establishing a theoretical framework for understanding the interactions of the classic low vision parameters of Bigger, Brighter and Bolder, and how we can use them to prescribe the most effective low vision aids. The second section concentrates on just the relationship between magnification and illumination, because those are the two parameters we are using with optical magnifiers. The third section expands the discussion to include contrast, which is critical for an understanding of newer electronic magnifiers.

I bang on about illumination especially, because I think it often gets neglected, and it deserves to be taken more seriously.

Know when to use magnification, when to use illumination, when to use contrast enhancement, and when you need to use a mixture.
What 'Bolder' Means
The word Bolder here means higher contrast, not a bold font. Bold fonts have a wider stroke-width, so if anything they would be considered a type of magnification, but then you get into issues of font readability, which is something I’m not going into.

Low Vision Rehab for Fluent Reading and for Spot Reading Are Waaay Different.

The fourth section uses the theoretical framework to concentrate entirely on the high-performance task of fluent, immersive reading, with special reference to the impact of patchy macular fields, and discussion on how we can help patients achieve reading for pleasure.

‘Spot-reading’ and fluent reading are not the same thing. We help people achieve spot reading so they can retain their independence. We help people achieve fluent reading to preserve their quality of life. Fluent reading is the more difficult task, so it’s affected much earlier in the disease process, and is very often the presenting complaint. It can be a source of intense frustration (both for the patient and the optometrist), so I hope a deeper understanding will help you be more effective in helping your patients.

Trouble with fluent reading is a common early symptom in low vision.

Not All Magnifiers Are Suitable for Fluent Reading.

The fifth section is a discussion of why some magnifiers are particularly suited to helping achieve fluent reading and some are really only suitable for spot reading tasks. This is so you can be more efficient, going straight to the aids that have the most potential to deliver the best results and avoiding the ones that are likely to be dead-ends.

Get the illumination right first.

Special Considerations

Throughout the sections relating to theory, I contrast patients with early and late AMD with patients with normal vision. I chose AMD because AMD makes up the bulk of our work at the Low Vision Clinic. But in the sixth section I move on to discuss how vision impairment from other conditions can be considered within that same framework, and the implications for how we might best help those patients.

Ring scotomas are common and perplexing. Make sure you understand them.

And the Award Goes To…

Finally, I wrap up with a longish post about my favourite magnifiers for fluent reading, relating them back to the theoretical framework and giving tips on how to use them best.

Electronic magnifiers are the best.

I wish you happy reading!

A note on the images I've used
A great many of them are diagrams I’ve created myself. (I’m an optometrist, not a graphic designer, so please excuse any deficiencies in them). However, I’ve also been a bit of a bower-bird over the years, accumulating all sorts of images from across the internet and photographed from texts, which I’ve used to illustrate my lectures. After all this time, I have no idea where many of them came from. If you find an image on my site that is yours and you’d like a credit, please let me know. Or if you’d like me to remove the image then of course I’ll do that too, but I hope you don’t — this is meant to be an educational site for the benefit of all.
I’m happy for my work to be linked to for the purposes of public education. However, you may not pass off my work as your own, and any reference to the work in this website must be accompanied by a credit to me.
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