Using a special machine which makes this measurement, the corneal surface (the outermost part of the eye, the clear layer in front of the coloured part) is evaluated. It is a non-invasive test tool. The obtained data are shown numerically and in the form of a coloured map.

Figure 1

It is used in the evaluation of corneal astigmatism, in the diagnosis of corneal diseases such ass keratoconus and to determine any irregularities on the surface of the cornea. There are devices nowadays that also evaluate the posterior surface of the cornea. Especially in the treatment of refractive errors, it is an indispensable means of measurement in refractive surgery.

Figure 2. Tomography map of a healthy individual (left) and a patient diagnosed with keratoconus (right).