The best solution for me was reading ebooks on an iPad. For one, the iPad is large for an eReader and you need large when you have a vision problem. Also, the iPad has full assistive capability so for awhile I was able to change the whole iPad so it was a black background with white print (they use this combo at Centers for the Blind or Legally Blind). Plus the iPad has a full inner light which allows me to crank up the light behind the print and thus the contrast. I needed all of these features to cope with my sudden vision problem.
What the iPad did for me was handle my vision problem so that I could still read anything that I wanted to read. I had a ton of apps for reading and I found one app, Marvin, which let me have the maximum adjustments for fonts. I used a font called chalkboard which is very bold and made the text as large as it was bold.
Marvin also let me take the text right to the edge of the device so I did not have to waste valuable space on wide margins. Marvin only exists on the IOS operating system, which is for iPad, iPad Mini and iPhone.
The below shows a Marvin book page with chalkboard on my iPad with the Fonts adjustment settings open and set to chalkboard. Make sure you click on the image so as to see it in full size.