Rare complete set of 130 stereocards divided into 12 categories. The cards were made to help in diagnosing the type and intensity of strabismus (crossed eyes). The stereo cards were designed by Dr. Emil Hegg of Bern Switzerland. Their chief advantage, lie in the very rich assortment of pictures, allowing for measurement of different types and strength of the strabismus. This set is very unique because of the latge number of color pictures.. This is a first edition of these cards, published by Schmid & Francke verlag in 1899 also included is a small original booklet explaining in German the uses and diffrences in the cards.