Wiktionary
n. Something worn to shield the eyes, especially a visor attached to an American football player's helmet.
Wikipedia
An eyeshield is a piece of football equipment. It is a visor that attaches to the helmet of a player to protect the eyes. It leaves the mouth exposed and covers the eyes and nose. Only clear eyeshields are allowed in high school football as the eyes are needed to be seen while checking for concussions. On the college level, a tinted eyeshield may be used if the player has eye problems. The NFL allows dark visors, (smoke or black) and reflective mirror visors, but does not allow colored or iridium visors.
The first football visors were made by Oakley and are currently being made by name brands such as Nike and Under Armour as well as many other sports and eyewear companies.
Usage examples of "eyeshield".
Light leaked up from beneath the eyeshield, causing the innards of the helmet to glimmer.
Far Rider, his waxy body, huge eyeshields, and alien physiology giving Dem Lia a slight chill.
He clamped his mine mask on and adjusted the eyeshields to screen out the smoke.
Smoke from the fire had gathered along the riverbank so that even their eyeshields were ineffectual.