Hi Adele
yes.
and not only towards the end. I registered my wife as blind this summer. She could outlive me, and I'm 7 years younger than she is. Her effective sight had been gone at least 6 months, but no-one else ever seemed to notice it.
The blindness is not organic - that is, the eyes could see if the neural connections were able to interpret what the eyes were seeing, or if the eye muscles could be controlled by the brain to focus. The eyes drift away, one eye may go lazy.
a complication is that the speech is often also impaired, so they can't say they can't see, and they can't explain to a consultant what they see when placed in front of an eye chart. I simply explained what was wrong to the consultant, he said "I see" and he signed her off as blind.
So what do you do to get attention? I sit nose to nose with my wife so she can feel me next to her; I talk all the time so she can sense direction. I say my name all the time, in case one time she can recognise it. Sometimes she gives the most beautiful smile and may even say "oh yes", and that makes any and all my efforts worth while.
On top of all the other problems, the blindness seems the cruellest stroke.
It is possible that your Mum is not blind of course. Sometimes the patients retreat into themselves and the eyes can just de-focus as they do that.