A teardown of a very interesting bit of optometry kit, a Shin Nippon NVISION K-5001 RefKeratometer (Auto Refractor Keratometer). It can measure the curvature of your cornea, and well as refractive error to diagnose near and far sightedness.
Links: https://www.rexxam.co.jp/themes/eye-care/products/images/nvk5001/NvisionK5001.pdf
https://www.academia.edu/59315264/Clinical_Evaluation_of_the_Shin_Nippon_NVision_K_5001_Grand_Seiko_WR_5100K_Autorefractor
https://www.opticsforhire.com/blog/keratometer-optical-design/
Manual: https://www.yumpu.com/en/document/read/25018677/english-manual
Forum: https://www.eevblog.com/forum/blog/eevblog-1554-optometrist-autorefractor-keratometer-teardown!/