Abstract: A measuring instrument particularly adapted to making accurate measurements of portions of the eye and contact lenses is characterized by a split mirror system in which one mirror is fixed and a second mirror rotates upon movement of handle-pointer associated with a scale. The object to be measured is magnified, and the magnified image is split by the mirror system until opposite edges of the split image coincide, whereby a correlated linear measurement is indicated on the scale. The instrument includes a light to illuminate the work area and an attachment for measuring the diameter of contact lenses.