PASCAL is always ready for operation; simply swivel it into place before the patient’s eye, zero the pressure sensor with a single click of the Blue Knob, advance the SensorTip to rest against the patient’s eye. After a few seconds a sound will tell you that sufficient data have been collected. Pull back now, and immediately you will see the numerical result, precise and unambiguous, on the PASCAL’s illuminated LCD display.

When the concave surface of the SensorTip touches the corneal surface, a solid-state piezoresistive pressure sensor, built flush with the center of the tip surface, directly measures IOP across the cornea. The contoured surface of the SensorTip has been calculated to generate minimal distortion of the cornea (contour matching) and hence minimize tension forces within the cornea during a measurement.

The PASCAL can be mounted on any slitlamp and is advanced towards the patient’s eye by using the slitlamp’s joystick. The SensorTip is mounted on a spring-loaded Cantilever which provides a constant appositional force against the cornea of 1 gram, eliminating any concern of over-compressing the cornea as is possible with other tonometers.

The pressure in the eye is detected 100 times per second and is digitized and stored in the PASCAL’s memory. A built-in microprocessor determines the intra-ocular pressure (IOP) and its pulsatile fluctuations caused by the patient’s heartbeat (ocular pulse amplitude, or OPA). The IOP and OPA are displayed as numeric values on the LCD display, along with a Q score which reflects the quality of the data obtained during the measurement.