Walker says the big advantage Apple has over Google's Android operating system when it comes to the visually impaired is that it controls the whole technology stack, and the software works across Macs, iPhones and iPads.
The many manufacturers building on top of Android phones and tablets, by contrast, make it difficult, because "as you start manipulating the operating system, you tend to break accessibility first," he said.
Within the Apple universe, the iPhone is where most of the third-party developers are focused. LookTel Money Reader uses the camera to announce the denomination of dollar bills, Alarmed helps stay organized with reminders and timers and the KNFB Reader lets users take pictures of any text and have it read aloud.
Dropbox, the popular Web storage and collaboration service, created an experience for the visually impaired by adding text for images, including additional text for context and building semantic functions understandable to people using screenreaders, said Cordelia McGee-Tubb, Web accessibility engineer at the San Francisco-based company.
Using Apple's built-in technology, makes "the process of developing for accessibility significantly easier, requiring much less technical work from the ground up," McGee-Tubb said.
Be My Eyes, which was started in Copenhagen, is another app gaining adoption. It uses video to connect a blind person with a sighted volunteer for help with a particular action, like checking the expiration date on a carton of milk.