DCT Principle

Prof. Goldmann stated, for a correct measurement of the IOP the corneal tissue
must be tension free.

1. IOP induces tensions in the cornea as it pushes against the cornea,
but the non-stretchable collagen matrix holds the corneal shape.

2. The cornea is tension free when the pressure is equal on both sides.
(Pascal’s Law)

3. When the pressure is made equal just in a small part around the center
of the cornea,the center becomes radial tension free and flattens.
The flattening comes from surrounding tensions pulling on the relaxed middle
section. This new shape is called the DCT-shape and the DCT tonometer tip
is formed accordingly.

4. During a measurement a tonometer tip with the DCT shape is brought in contact with the eye. The adhesion of the tear film causes the cornea to conform to the DCT shape of the tip and frees the cornea again from its radial tensions. This allows direct measurement of the IOP as if there were no cornea.


Click here to watch the video on the DCT Principle

DCT Principle

DCT Principle