I need to understand how Sirius works in order to be confident with the results that I am obtaining in my experiments.
The Sirius acquires 25 Scheimpflug images and a
Placido-disk image with 22 rings in a scanning process.
Anterior surface data are calculated by merging
Scheimpflug and Placido-disk images. Data for the internal
structures (posterior cornea surface, anterior lens surface,
and iris) are derived only from the Scheimpflug camera.
http://journals.tubitak.gov.tr/medical/issues/sag-13-43-2/sag-43-2-19-1203-92.pdf
Thank you Peirpaolo for your answer, and congratulations for your work.
But I need a more technical answer. I understand how the Sirius acquire the images. The question is how it process them. How the Sirius extracts from the images, the value of the ACA. What kind of image processing it does. Is the ACA calculated from the endothelium to the iris? What part of the iris??
Hi Justo, you can check it be reviewing the Scheimpflug scans
you can see the detected surfaces corresponding to anterior and posterior corneal surfaces, iris and anterior lens surface each one in a different colour
from the "angle" approxmation of the iris to the posterior corneal surface (I can check for how much width/length of the segment) the ACA is obtained.
By cehcking the different colours you may actually correct/edit some subtle errors in auto determination.
By playing with this in a "fake" manner you may underatand the was it is working.
Thank you Sam, could you tell me what kind of errors in autodetermination can occur?
well wrong recognition of anterior or posterior surfaces, specially in pathologic corneas.
hyperreflections leading to overstimated pachymetries...
I can send you tomorrow an email with more details.
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