1. Scanning Tonometer for Eye Pressure (STEP™) Problem Measurement of eye pressure by Goldmann applanation tonometry is a technique first embodied in the late 1950’s. Tonometry is faced with a number of unknown variables including elastic resistance of the cornea, surface tension of tears on the eye, and changes in eye pressure with cardiac and respiratory pulse. Solution Goldmann and instantaneous (air-puff) measures of intra-ocular pressure are always flawed by time bound (0.5 to 12 seconds) changes in eye pressure. The Scanning Tonometer for Eye Pressure (STEP™) overcomes all the above limitations of state-of-the-art tonometry and provides information on corneal integrity.

2. STEP™ Glaucoma Assessment The standard technique for Goldmann applanation tonometry is automated to enable inclusion of variables that change the reading as a function of tear volume, corneal elastic resistance, and the cardiac and respiratory pulse.

3. References  Whitacre MM, Stein R. Sources of error with use of Goldmann-type tonometers. Survey of Ophthalmology 1993 July-August; 38(1):1-30.  Aggarwala KR. On the short-term variability of measurements of intraocular pressure. Optometry and Vision Science. 1995 October; 72(10):753-5.  Lam AK, Lam CH. Effect of breath-holding on pulsatile ocular blood flow measurement in normal subjects. Optometry and Vision Science 2004 August; 81(8):597-600.