pigo

I'll use this post / opportunity to ask the HN community (I understand that this is a technically complicated, and potentially sensitive subject) I've been approached by a few people who are doing what they can to lower the cost of prescription glasses. It's a mix of (licensed) ophthalmologists, people interested in offering community health services, etc. What is the current state of the art for pupillary distance (PD) measurement based on face detection / pupil tracking using laptop webcams or mobile (front) cameras? I imagine (obviously?) that there must be scholar research on the acceptable error margins for a PD measurement (depending on the type of vision condition, i.e. farsightedness, etc.)? Would using something like Handsfree.js or https://github.com/esimov/pigo (which has pupil detection) be a good start, or would these be an ~