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.
00:00 - What is an AutoRefractor Keratometer? 03:41 - Don't try this at home kids! Can Dave measure his eyeball? 06:17 - Teardown 08:14 - Pupil distance measurement 09:43 - Should have read the manual... 11:22 - How the Keratometer mire circle is generated 13:42 - Optical path and lenses 15:47 - The camera 16:53 - Fine auto-focus mechanism 18:22 - Main PCB