This is old now, but I think it still holds true:
"Heilbrun (1991) dared to name midlife invisibility, celebrate it, and define it. She called it the "magic circle of invisibility [through which one passes] into the land of new accomplishment and new passion" (p. 27)—hardly the self-esteem problem defined by Sheehy (1991).
"To get to that new place," Heilbrun (1991) declared:
a woman must pass through the state of invisibility. You will be mysteriously unseen. You will not be noticed immediately upon your entrance in a store, a party, a meeting. You will move invisible for a time, to learn to see, and to forget being seen. As you grow slowly visible in the new life you have chosen, you will be heard more and seen less. Your voice will ramify; your body will become the home of a new spirit."
Perhaps some of us are fortunate never to feel that state of invisibility, but many others feel it more strongly. It seems to me the important thing is to deal with it as well as one can and develop a new sense of identity in older age. I think that can be very liberating.