If an elderly hospital pt who has untreatable macular degeneration reports a further loss of vision then, normally, would it be a waste of time for the hospital to even look into the matter?

Any loss of vision: should be investigated as the cost of low vision societally is huge. However, in many socialized medicine countries, the older the patient, the less public health dollars are available for care to treat 'untreatable' conditions. There is wet and dry AMD. So, in either case, it does warrant further ophthalmological care to prevent against blindness.