We recorded the exact IOP values and the exact clock times for each measurement. We randomized the order sometimes he tested first, sometimes I tested first. We repeated the side-by-side comparison three times throughout the office visit. Ideally, you should remain seated in the same place and there should be no delay between tests. So the testing needs to truly be side-by-side. Your IOP can change within a couple minutes even if you don't move around. Getting up and walking can change one's IOP. We set it up so that he could do Goldmann tonometry on me and I could check my IOP with my tonometer with no delay and without me moving around. He dedicated an exam room for our little experiment. When I last took my home tonometer to my doctors office, we did the side-by-side comparison as follows: (Goldmann tonometry averages the cardiac cycle out of the reported IOP, but some home tonometers give you the exact, non-averaged, instantaneous IOP.) IOP can change very quickly for a wide variety of reasons including stress.
![icare tonometer icare tonometer](https://www.main-line.co.uk/wp-content/uploads/2018/12/TP01_Image1.jpg)
It can change 3 to 5 mmHg with each heart beat. Why?īecause for many (maybe most) people, eye pressure is dynamic (it's constantly changing by a few points). Many people do not do this step correctly, and they are misled about the accuracy of their tonometer. Second, compare the tonometers side-by-side. Goldmann Applanation Tonometer Calibration Error Frequency | Ask FitEyesīrawn Medical Blog on Goldmann Tonometer Errors and Calibration | Ask FitEyes It makes little sense to test your new home tonometer against a device that is likely out of calibration. Why?īecause most Goldmann tonometers in clinical practice are out of calibration. Start by asking your doctor when the Goldmann tonometer was calibrated and how close it is to the recommended calibration accuracy.
![icare tonometer icare tonometer](http://topconhk.com/wp-content/uploads/2017/08/IC100_product_image_square1-1000x9001.jpg)
This discussion, I will assume your doctor is using a Goldmann tonometer and you are using an iCare or Reichert.įirst, find out exactly what you are comparing against.