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Generally speaking optometrists measure the core measurements of how your vision is and make the prescription.
However, to make glasses as well as the prescription they need the interpupillary distance (IPD); how far apart the pupils in the centre of the eyes are.
The IPD rarely changes much / at all in adults (so saving for certain conditions, once you know it you could keep using that value), and measuring it is not that hard if you have another person to do it (read how to do it properly on the Internet).
I don’t know the law in Canada around what they have to disclose. I believe Canada has privacy legislation that says that people have access to private information about them held by companies in at least some cases, so that might be something to look into, and then request all the information they hold on you if you ever need the information again.
Starlink is a constellation of low-earth orbit (LEO) satellites, not geostationary satellites. That means that the ground station (i.e. subscriber equipment) talks to one satellite as it comes into view, and over time that satellite moves across the sky, and they switch to another satellite. This means the latency is highly variable as the distance changes, but at its lowest is much lower than a geostationary satellite since it is far closer.