My wife has a large collection of photos kept on my PC and she selects some to print. I bought an iPad so she could look through all of them but she has never mastered it.

Glaucoma and cataracts are now severely limiting her vision and I want to find some sort of very easy to use photo frame or tablet that she could put on her lap.

Most of the ones I have looked at have a lot of extra features that will just confuse her - all she needs is a "NEXT" button and the biggest possible screen. I can copy her whole 10 years worth onto a memory card or usb stick so the only other thing she will have to learn is selecting from a menu.

Suggestion for something suitable will be very helpful

Thanks  Posting the images to an online cloud storage and then VIEWING them through browser might be easiest. If you know HTML you can even make a very simple user interface to move to the next picture and not have extra features that are confusing.

If the images were named say 1 through 500 you could have a very simple HTML page that has 2 arrows one that goes from say picture # 3 to picture # 4 as an increment to next image, as well as an arrow pointing to the left that decrements from say #3 to #2.

I'm not familiar with iPads, other than that I know that they can view HTML web pages very well, so if you had an interface that was HTML for the pictures, then navigation would be easy and it would work on any computer or device with a browser vs software that is platform specific.

Hardest thing would be getting all your images into a numeric file name format where each image has a unique number. After that the HTML to pull it off is very easy and I could provide that if your not familiar with HTML.

You could even have the images and the HTML on a MicroSD card and view it off of that through whatever browser your using.Thanks, but I'm only half a step ahead of my wife with computer (lack of) skill.

If I download all her files onto a memory stick or card I can keep the pictures in the same dated folders so just need the simplest way of seeing them.Allow me to expand on what DaveLembke said.
Most people are not going to master tablets and computers. It just does not happen.
Using a photo sharing service might be the best you can do. Here are my thoughts.
1. The Photo Sharing serve is not limited to just one brand or type of computer system.
2.  A good service pays more attention to just photo sharing, not games and shaping stuff.
You can search for this topic:

Free Ways to Share Photos With Friends and Family

But avoid Facebook, It is overkill.

Here are some ideas I like:
https://www.howtogeek.com/133062/the-best-free-ways-to-share-photos-with-friends-and-family-other-than-facebook/

https://www.familysearch.org/blog/en/turn-photo-collection-chaos-order-simple-tips/

You may re think the use of paper and cardboard boxes:
https://www.lilblueboo.com/2012/12/tips-for-creating-simple-and-timeless-photo-albums.html

Of course, there are lots of firms that will sell you something.  Avoid them. Instead, get  you grand KIDS involved in helping your do some kind of private internetphoto sharing plan.
Ask you kids about their sill with any of these:
Flickr
500 Pixels
Photobucket
Canon Irista
DropBox

I hope this  is of some help. Soon there ILL be some new gadgets on the market designed specific ally for Internment family photo sharing. But let you kids discover which are worthwhile. Meantime, use a free photo sharing Internet service.

EDIT: Hardware? This answer is not just hardware. Some new TV sets are coming with the kind of things you may want for family photos.  But let your kids discover what is best. Meanwhile, plan of using a internet photo  sharing service. They work with any kind of PC, tablet or smartphone.I believe gents he's lookin to use a simple picture viewer... Quote

I believe gents he's lookin to use a simple picture viewer...