Which device would you use as a gold standard for verification of the project relate real keratometry of the eye. I want to verify the anterior, posterior and the real power, Sim K of the posterior, anterior and true values.
I was thinking about Casia 2000 SS-OCT from Tomey but they do not have FDA. So, what would be the best reference for the prototype software: maybe Pentacam or GALILEI from Ziemer.
Kind regards,
Bart
No doubt wavefront analysis is the new gold standard. I Would recommend Orbscan or pentacam.
Oculus Pentacam for certain--precision, reproducibility, ease of use and relative immunity to tear film disturbance all set it apart.
Current Scheimpflug topo/tomography leaves much to be desired concerning the posterior surface mapping. Swept Source OCT-based topo/tomographers like Casia 2 by Tommey or the unit from CSO seem to do a better job in that respect. Maybe even IOL master 700, which is also SS OCT-based, maybe better for your purpose (estimating the K-values from the posterior) than the Pentacam.
Thanks a lot!
Some people say that Casia readings are not very stable. What is your experience?
In my clinical experience in daily use of both Casia 2 and Pentacam the measurements with the former are at least as repeatable compared to the latter.
Actually there is no one single device that have all advantages. However, I will choose to have two devices that complete each other, Pentacam and Orbscan.
I do also recommend the Pentacam. The precision of the height data, which is used to calculate the radii, is about 5microns. Maybe we see in the future OCT technology which has an even higher precision. So far it is not reported.
One of the huge advantages of the OCT topo/tomography is the patient's examination comfort, due to the very short duration and no disturbing light. This is not only a convenience, but also translates to less artefacts and much better coverage. One could argue that you may hold or tape the patients eye during the Pentacam exam, to obtain the same coverage, but that in itself introduces artefacts. As short exam as possible and the least disturbing as possible exam for the patient is essential for obtaining reliable results.
Thanks a lot! I also believe in OCT. That is why I am working on it :-)
Dear Sebastian, the problem with OCT technology is to take a measurement in a proper position.
My favorite is the Galilei (Zeimer) tomography-topography system.
If the gold standard assumes a device that is the most prevalent and the one that we can compare the other topographers with, then it is definitely Pentacam, although many other units may be better in one way or another. As mentioned earlier, the future lies in OCT technology, the fanciest of all currently being Anterion by Heidelberg.
Dear Aleksander,
Thanks for your opinion. I absolutely agree with you. I am just working on OCT topography and keratometry. That is way I asked my question. The topic is quite complicated, anyway :-)
Depende de lo que queramos analizar con la topografía. El Pentacam es tal vez la más estudiada en nuestro medio y ofrece buena información sobre el perfil corneal de manera cualitativa y cuantitativa si me refiero solo al análisis de córnea pero para el cálculo de los lentes la imagen topográfica de cara anterior de la mayoría de los topógrafos es excelente. Las cosas no son buenas por si mismas sino que depende de para que se utilizan
You can check your tomographer by objective way by test model eye or comparing with other instruments. OCT based, slit beam scanning and reflection from ant & post surface of cornea are present available principle.
There is a subjective method to confirm accuracy of your tomographer by simple vector analysis of magnitude of ant & post surface astigmatism with refractive error of that patients.
Every instruments give different keratometer power as use slightly different values of ref index, and measure in different zones.
So gold standard is yet to come