Beware of OIS7
I can barely see an eye chart but can point a camera and do a lot of photography. We have put OIS 7 on my iPad and my wife's iPhone. Her eyes are very good. I use a mouse and zoom to navigate my mac's 28 inch monitor and let the mac read the text. I use voiceover on both the phone and iPad. Now, outside, with 7 she can not read text in Contacts and other places. I can not use the camera controls on the devices. We have turned up text size, contrast and bold with little effect. Our older iPad still uses IOS 6. It is much easier to use and read.
I switched to the Macintosh many year's ago because of it's crisp clear text and icons. Now that is not in style at Apple. We will be going to the Apple store to see if it is possible to switch back to 6. If not maybe they will trade for devices that have 6. If not, we will walk to the Microsoft store to look at Nokia and then check out the Android options. Too bad Apple does not seem to test things with people with poor eyesight. They need some good industrial designers who believe form should follow function.