Build me an app using iPhone 12 Pro's LiDAR - spatial calibration and measurement -- 2

I would like to measure in millimeters precision an area in the eye, specifically the mean reflex distance (MRD): [login to view URL] I am aware the iPhone 12 Pro's LiDAR isn't mm accurate (low quality), but I have an idea of how to utilize it. Let's say I take a standard card (ISO 7810 ID-1: 85.6 X 5.398cm) and hold it in front of my face for spatial calibration. [login to view URL] The LiDAR rays could hit the card at various points and calculate its distance and if it's tilted or not. The LiDAR rays would also hit the skin around the eye (and even better - the cornea or sclera around the cornea), and through an algorithm, it could subtract the distances and get an actual measurement of the eye in mm. [login to view URL] Sounds feasible?