Muller cells are living optical fibers in the vertebrate retina.
Franze K, Grosche J, Skatchkov SN, Schinkinger S, Foja C, Schild D, Uckermann O, Travis K, Reichenbach A, Guck J. Muller cells are living optical fibers in the vertebrate retina. Proc Natl Acad Sci U S A. 2007 May 15; 104(20):8287-92.