2010 ADA Standards for Accessible Design Pocket Guide
404.2.11 Vision Lights.
Doors, gates, and side lights adjacent to doors or gates, containing one or more glazing panels that permit viewing through the panels shall have the bottom of at least one glazed panel located 43 inches (1090 mm) maximum above the finish floor. [S.H. 4.13]
ETA Editor’s Note:
An existing door with a noncompliant vision light is a safe harbored element for path of travel and barrier removal purposes but will have to comply when the door is replaced.
EXCEPTION: Vision lights with the lowest part more than 66 inches (1675 mm) from the finish floor or ground shall not be required to comply with 404.2.11.