Fig 1. Glasses used in the study.
From left to right, inward-sloped, straight-sided, outward-sloped.
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.