The HAAG-STREIT OM 900 Ophthalmometer uses a classical distance-independent measuring principle which meets the three requirements of Helmholtz:

1. The size of the mire image is independent of the distance between the Ophthalmometer and the measured object.

2. The resulting measurements are independent of the distance between the Ophthalmometer and the measured object.

3. The measurements are independent of the quality of focussing and are not negatively affected by the accommodation of the user.

Tables and Units