Should I replace her glasses

My Mom is in late stage Alzheimer and lives with my sister in another state. She has all the late stage symptoms. She has worn glasses her whole life. She has recently broken her glasses and my sister can only find one lens. We don't know where they were purchased since she lived in another state before she came to live with my sister over 10 years ago. I found a vision doctor that is willing to replace the glasses with two lens identical to the one my sister found. My Mom is not able to communicate to take an eye test and it would be very difficult to get her to the doctor. My sister is not interested in spending the money to replace the glasses. Should I replace the glasses or is her vision probably to poor to see clearly My husband thinks that she can't see much anyways Ideas