Starting from the first stages of embryogenesis and continuing afterwards, most body parts are programmed to achieve a certain size and shape. The eye shares a similar homeostatic mechanism but, in addition it needs vision as input to growth control (Wallman and Winawer, 2004). However, for still unknown reason the eye often grows too long and becomes myopic this way (shortsighted), or it does not grow long enough and consequently gets hyperopic (farsighted).

Maria Alexandra Marchã Penha, MSc Biochemistry by University of Beira Interior, Covilhã, Portugal. PhD in Biological Sciences at Eberhard-Karls Univeristy, Tuebingen, Germany.