Acknowledgment: We thank Terry Omond OA, Curator of the Calvary Hospital Museum, for the loan of the instrument.
Increase of the intra-ocular pressure is a common condition. It is known as Glaucoma and untreated resulted in blindness. Early diagnosis and treatment are now available. Professor Schioetz demonstrated his instrument to the Norwegian Medical Society in 1905.
The tonometer measures the amount of indentation of the cornea when a small weight is placed on it. The result is inversely proportional to the intra-ocular pressure and tables are provided to obtain the pressure value in mm Hg. The indentation tonometer required the cornea to be anaesthetised. It was used world- wide for the next 60 years. Later, as always new technology provided many improvements which increased the comfort and accuracy.