Twin brothers Jörg and Rolf Fischer sleep together at Rolf's dormitory in Germany. Both were born deaf, and they have lost their eyesight because of diabetes -- although Rolf can still see a little bit out of one eye. Photographer Marlena Waldthausen spent a few months with the twins and learned how they navigate the world together.
Like most deaf-blind people, the twins use tactile sign language. They take each other's hands and form signs with the hands and arms of the other. They also use the Lorm alphabet, where every letter corresponds with a point on the palm. Over the years, they've even developed their own signs -- so their conversations are often hard for outsiders to understand.
Jörg pushes Rolf through the water during their weekly swim therapy.
The twins spend some time at the beach.