Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Prior to the second pass, the blue locking ring is loosened so that the guide ring can be rotated (A). The reference mark (thick arrow) is now turned 180 degrees away from the initial alignment mark (thin arrow) (B). Central pachymetry is remeasured (C) prior to the second pass (D).
