An official website of the United States government
Here's how you know
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.
CE-US changes over time in the R (II) group (luminance score). A: B-mode; B: Pre (0.96); C: Post 2 course (0.99); D: Post 4 course (1.0); E: Post 7 course (0.93); F: Post 11 course (1.0).