Adventures In Accessibility #2: How the Blind See the World

by Kwasi Mensah

December 20th, 2010

Introduction

So I’ve spent a lot of time figuring out how people with no vision  are going to play the game I’m working on. I’ve already circled in on a solution but I wanted to take some time to look into supporting people with low vision. By low vision I mean people who are “legally blind” i.e. aren’t completely blind but have seriously compromised vision.[1]

While complete blindness can be simulated by closing your eyes, low vision is a lot more complicated. There are several causes of low vision and each have their own symptoms. Low vision is actually more relevant since only 10% of people who are legally blind have no vision whatsoever.[2] This means the vast majority of blind people can still see in some capacity.

Using statistics from the World Health Organization [3] I’ve decided to focus on the low vision cases below. And in order to bring home how this differs from normal sight I’ve decided to release my inner artist . Under each section I’ll show a manipulated image that approximates how someone with low vision would see this same picture.


Unaltered Image of Kwasi

Age-related Macular Degeneration

(50% US, 8.7% worldwide)

Image of Kwasi Altered to show Macular Degeneration

Macular degeneration is a loss of vision in the center of your field of vision. Objects will start looking distorted and dim. What’s important about this disease is that it’s most common in people over 60 (hence the “Age-related” in the title).

Google Health Link on Macular Degeneration

Glaucoma

(18% US, 12.3% worldwide )

Image of Kwasi Altered to Show Glaucoma

There are actually four types of glaucoma. The most common type in the US is open-angle glaucoma which causes people to lose peripheral vision.

Google Health Link on Glaucoma

Diabetic Retinopathy

( 17% US, 4.8% worldwide)

Image of Kwasi Altered to Show Diabetic Retinopathy

People with diabetes are the most likely to get this condition. There are several symptoms at play in the pictures above. There’s blurred vision, floaters, and missing areas of vision.

Google Health Link on Diabetic Retinopathy

Cataracts

(5% US, 47.8% Worldwide)

Image of Kwasi Altered to Show Cataracts

While this is relatively low cause of blindness in the US it’s far and away the largest cause of blindness in the world. The symptoms you see in the picture above are: cloudy vision and  loss of color intensity.

Google Health Link on Cataracts

Arts and Crafts

Alas, my art skills only go so far. I wanted to be able to see the world as someone with low vision in real time. There’s are several sites that let you simulate different types of low vision [4]. But I wanted to see my game on my iPhone with the disability.

So with combination of cheap reading glasses, gray plastic film, an x-acto knife and super glue I made these puppies.

Glasses that are supposed to Simulate Macular Degeneration

They’re meant to simulate a really bad case of macular degeneration.

Seeing a Mile In Their Shoes

The first thing I noticed was that I had no problem walking around my apartment. I lost a lot of detail but I could easily make out tables, couches and other large objects. In fact, only a tiny percentage of blind people use canes or guide dogs to get around.[5] Many go through special training to learn how to navigate on their own with the vision they have left.

However, the moment I tried to sit back down and finish writing this post I was completely lost. I couldn’t make out anything on my two monitors. I couldn’t even make out the keys on my keyboard. Any text that I tried to read that wasn’t huge became an incomprehensible blur. This gave me the opportunity to try another cool piece of Mac OS X’s accessibility tech, Zoom. Zoom lets you magnify the contents of the screen up to 20 times.

Screen Before Zoom is Applied

Screen with Zoom applied

It took a a fair amount of zooming before I could make out text in my peripheral vision. It also became hard to navigate the screen as Zoom doesn’t change the logical resolution of the screen but picks a part of it and blows it up. I could move the part that’s magnified by using my mouse but it became hard navigating around the window.[6]

Conclusion

Obviously, my glasses aren’t a replacement for actually testing the game with people who have low vision. Plus, I’m pretty sure its not a good idea to wear them for extended periods of time. I’m still going to approach visual accessibility from the no vision route for now. But knowing that large actions can still be read leaves room for secondary visually feedback.

Notes:

Note 1: From wikipedia’s article on Low Vision: (http://en.wikipedia.org/wiki/Low_vision): In the United States, any person with vision that cannot be corrected to better than 20/200 in the best eye, or who has 20 degrees (diameter) or less of visual field remaining, is considered to be “legally blind” or eligible for disability classification and possible inclusion in certain government sponsored programs.

Note 2: From the American Federation for the Blind.

Note 3: : All statistics about blindness come from the World Health Organization paper “Global data on visual impairment in the year 2002” by Serge Resnikoff, Donatella Pascolini, Daniel Etya’ale, Ivo Kocur, Ramachandra Pararajasegaram, Gopal P. Pokharel, & Silvio P. Mariotti . When this blog post was originally written a pdf of the report could be found at this url.

Note 4: Checkout The Foundation of the American Academy of Ophthalmology.

Note 5: This number is really fuzzy. Using the stats from the American Federation for The Blind, there are 25 million Americans with serious vision loss. The best data we have about cane usage is a study putting the number at 109,000 in 1990 (see the mobility section on the same page). And only about 7,000 blind people use guide dogs.

Note 6: : Zoom is also supported on the iPhone. I ran into similar issues (easy to turn on and to zoom, hard to actually navigate content). I personally find Voiceover more useful but it has a steeper learning curve. I’d take this with a grain of salt as I’m not in the intended audience.

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