My experience has been that the range of my intraocular pressure measurements is greater when measured with a non-contact tonometer than when measured with a Goldman applanation tonometer. In the following article the researchers describe finding the same results.

Eye. 1993;7 ( Pt 1):134-7.

Intra-eye pressure range and pulse profiles in normals with the Pulsair non-contact tonometer.

Vernon SA.
Academic Unit of Ophthalmology, University Hospital, Nottingham, UK.