The Reichert Ocular Response Analyzer (ORA) is overkill for most home users. If you are part of the FitEyes community, you can learn how to get all the functionality you need from a Reichert 7CR, which is a much more suitable tonometer for home use and only a fraction of the cost of an ORA.
A Reichert 7CR in home use rarely needs servicing or recalibration. It self-calibrates each time you turn it on. If you simply keep it clean, it will continue to work perfectly for years.
The tonometer doesn't contain software that will become obsolete. You can use it with FitEyes software, and our software has been maintained since 2008 and is working well today. But even without the FitEyes software, your Reichert tonometer will continue to work. In my experience, a Reichert 7CR will likely last a home user for the rest of their lives.
An older post suggests getting details of serial number, measurements (presumably number the machine has performed), last calibration date (presumably only calibration by Reichert is acceptable).
That is a very old post and it was referring to a much older Reichert model -- the AT555. The AT555 has been out of production for more than a decade now. However, that old model is still supported by the FitEyes software. It can still be calibrated. And the hardware is built well enough that many AT555 models are still working very well, even after heavy use in a clinical practice for decades. But the air puff is not as comfortable as the 7 or 7CR. The new models are very gentle and comfortable to use. Most importantly, they are more accurate. The 7CR is especially more accurate. It is as accurate as the ORA and more accurate than almost any other tonometer in the world. See Is Goldmann Applanation Tonometer (GAT) the Gold Standard? | Ask FitEyes.
The reason we asked for the serial number of the AT555 is that this model, which had a very long production history at Reichert going back multiple decades, when through a significant revision at one point in its history. We do not recommend the older AT555 models (hence the need to check serial numbers).
However, today, I do not usually recommend buying any AT555. You can find a used Reichert 7CR at a reasonable price, and that is a much better choice. Any 7CR, regardless of serial number, is OK.
Here is a short summary of Reichert tonometers models that people consider when looking into self-tonometry:
NCT II - this model is not very accurate, it is not comfortable (the air puff is very hard) and it was out of production before FitEyes even existed. It was never a good choice for self-tonometry. I never recommended it, not even in 2006.
Reichert AT550 - also obsolete more 15 years ago. By the time I started FitEyes in 2006, this model was already out of date. However, it is the oldest Reichert model that can be used for self-tonometry.
Reichert AT555 (early generation) - as explained above, I do not recommend these unless there is no other choice.
Reichert AT555 (later generation) - not your best choice, but these are suitable for home use and they generally last for decades.
Reichert TonoPen - not recommended. It is a contact device. It is painful to use without anesthesia. It is very, very difficult (nearly impossible) to use for self-tonometry.
Reichert 7 - a modern tonometer that is suitable for self-tonometry.
Reichert 7CR - a modern tonometer and the best choice for self-tonometry. The 7CR is only marginally more expensive than a 7, yet it offers advanced features that make it the hands-down choice over the 7. Several FitEyes members who have purchased a Reichert 7 have subsequently returned them and upgraded to the 7CR. (Fortunately, they purchased new and from a Reichert dealer who allowed this exchange. But if you buy used, skip the 7 and get a 7CR). The advantages of a 7CR include the measurement quality score and the corneal compensated IOP value (IOPcc) which is a uniquely valuable feature for glaucoma patients.
I love my 7CR and have found the investment to be well worth it.
Today, I generally only need to recommend two tonometers: the Reichert 7CR and the Icare HOME models. The Reichert is easier to use and more advanced with its corneal compensation feature. The Icare is less expensive and portable. Many FitEyes members own both. But either one is a good choice. Every FitEyes member who has purchased any tonometer in the last few years has purchased one of these two. I cannot think of any tonometer on the market that would be a better choice than one of these two, regardless of price.
If you live in the USA, you can buy or rent an Icare at:
Enlivened Tonometer Rentals