<unk>  is an indentation<unk> , used to measure the intraocular pressure (IOP) by measuring the depth produced on the surface of the cornea by a load of a known weight. The indentation of corneal surface is indirectly proportional to the IOP.
Schiøtz tonometer
Perineometer
String galvanometer
Sphygmomanometer
Sphygmograph
Retinal vessel analysis
Laser Doppler imaging
Vertebral artery test