Can an Alzheimer's person be taken to the hospital for poor eyesight?

I'm not quite sure what problem you're anticipating.

Getting the person to the appointment? - shouldn't be insoluble, look at the logistics and plan the route.

The person's being able to interact with the clinician? - most ophthalmologists and ophthalmic opticians will be well used to working with older people, including older people with mental impairments. Call ahead and get advice on how to manage any difficulties the person might have with this.

Really, the worst that can happen is a wasted journey. So if you're concerned about this person's eyesight, go ahead and make an appointment.

Meanwhile, back at the ranch so to speak, if you're concerned about her managing safely at home there are several things you can do. Ideally get an occupational therapist in to assess her living space and make recommendations; but if that isn't possible look at:

trip and slip hazards - remove loose rugs, clutter and so on out of her way
lighting - make sure that her usual routes around the house are well lit
handles and rails - watch where she normally places her hands as she beetles about and place properly secured handles and rails where she naturally reaches; make them clearly visible, make sure they are comfortable for her to hold on to, make absolutely sure they are properly fitted and secure. If you're no handyperson yourself, get the job done professionally.

Having said that, it's important not to change so much that she can't adapt to it easily - muscle memory and familiarity become ever more important as dementia progresses. Hence this really is a specialist project, so if you can find an experienced OT so much the better.

I would not take her to a hospital. She should see an Ophthalmologist who is an MD. Not an Optometrist.

If she hasn't been seeing an Eye Doctor it could be a number of things. She could have cateracts or glocoma. Her Dementia could effect her eyesight. She could have had a stroke in the back of her head. My Mom lost her left peripheral vision. The eye doctor ran tests that showed no strokes. It was determined that her problem was probably caused by the Dementia.

If she's experienced sudden vision loss, yes. If it has been developing over time then her regular physician should be made aware and they can assess her and determine if she needs a referral to a specialist.

When was the last time her eyes were checked by an ophthalmologist?

I know it’s difficult to take her but she may be needlessly going blind. Is she diabetic?

My eyes were checked in the hospital when doctors couldn’t understand my blood work and thought I was having a type of neuralgia, Trigeminal neuralgia. In fact they told me I would go blind. This is an extremely painful type. Thankfully I did not have it. They produced an opthamoligist in the middle of the night so yes, she can be checked.

She may have had a stroke which can affect the vision. Happened to my uncle.

Please don’t wait until she is totally blind to get her medical attention.

Edit to say it can also be that she is having a perception problem and is afraid Of falling, this having to do more with her dementia. But she needs medical attention.

Has she seen an ophthalmologist?   An eye specialist could give you more insight, and perhaps solutions.  

Was she ever diagnosed with eye conditions that affect sight viability, such as macular degeneration or glaucoma?  There are treatments for that; they don't cure, but they can control deterioration.

As MidKid writes, we need more information.

Of course they can--but to what end? I don't really understand what you are asking. Does this person need a higher level of care? A hospital is not the answer.

Come back with more information and you will get better answers.