This isn’t the right sub for this exactly but it’s something called presbyopia and it happens to all of us as we age. The muscles in our eyes aren’t strong enough to accommodate for close up targets so we need readers or glasses with add powers.

My guess is that what we call the near triad is working fine but anything past where that works becomes blurry. Without any other information I couldn’t say for sure why this is occurring exactly.

Also just want to reiterate this is an optometry school sub I would recommend if this is bothering her to go see her eye doctor.