[Code of Federal Regulations] [Title 21, Volume 8] [Revised as of April 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 21CFR886.1640] [Page 457] TITLE 21--FOOD AND DRUGS CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PART 886--OPHTHALMIC DEVICES--Table of Contents Subpart B--Diagnostic Devices Sec. 886.1640 Ophthalmic preamplifier. (a) Identification. An ophthalmic preamplifier is an AC-powered or battery-powered device intended to amplify electrical signals from the eye in electroretinography (recording retinal action currents from the surface of the eyeball after stimulation by light), electrooculography (testing for retinal dysfunction by comparing the standing potential in the front and the back of the eyeball), and electromyography (recording electrical currents generated in active muscle). (b) Classification. Class II.