What is the principle of schiotz tonometer?

Schiotz tonometer works with “indentation” principle, which implies that higher IOP requires higher weight or force to indent. It measures the depth of corneal indentation by a plunger carrying a known weight.

What type of test is performed using the schiotz tonometer?

A Schiotz tonometer is an analog, weight-based tool to assess intraocular pressure. It uses a weight on a flat transducer which is opposed by the intraocular pressure. The IOP is transferred through the weighted tonometer arm and gives a reading on a needle, which is then used on a conversion table to calculate IOP.

Is eye pressure of 20 normal?

Your eye pressure is measured in millimeters of mercury, expressed as mm Hg. Normal eye pressure is between 10 to 21 mm Hg. High intraocular pressure is greater than 21 mm Hg.

How is IOP calculated?

The IOP can be theoretically determined by the Goldmann equation, which is IOP = (F/C) + P, where F represents aqueous flow rate, C represents aqueous outflow, and P is the episcleral venous pressure. A change or fluctuation in any of these variables will inevitably alter the IOP.

How is IOP pressure measured?

Your ophthalmologist will instruct you to position your head into a device called the slit lamp. Then, a small tip gently touches the surface of the eye and the eye pressure is measured. The eye pressure is measured based on the force required to gently flatten a fixed area of the cornea.

What does an eye pressure test show?

Eye Pressure Check A tonometry test measures your intraocular pressure. It’s like pressing a balloon to check for air. It shows how firm your eyeball is with the same measurement units used to check blood pressure. The normal range for intraocular pressure is about 10-20 mm HG.

How do you calibrate a Schiotz tonometer?

Calibration check procedure Place the footplate of the instrument on the rounded test block (the dummy cornea) provided with the tonometer’s storage case. With the footplate resting on the test block, a correctly calibrated instrument will have a scale reading of zero. If not, you can calibrate it to zero.