This HEM300 is used for precise exophthalmos measurements (e.g. exophthalmic goiter).Thebasis of the measurement for exophthalmos determination using the Hertel version is the outerorbital rim (orbital wall)l and the apex of the cornea.The integral refraction mirrors with milimeterscales for the left-hand and right-hand measuring halves of the exophthalmometer arecalibrated so that the zero mark on the scale will be located in the plane of the resting pointsof the supports. For exophthalmus measurements the supports are placed against the twotemporal orbital walls so that the orbital rim contacts the deepest point of the supports.