|This article is about Old Snake's eyepatch in Metal Gear Solid 4. You may be looking for the cardboard 3D viewer bundled with Metal Gear Acid 2.|
The Solid Eye was a device invented by Otacon (with the help of Sunny) resembling an eye patch. It was used by Solid Snake in his final mission to eliminate Liquid Ocelot. The Eye appeared to be similar to a plastic eye patch, with the text "SOLID EYE SYSTEM" and a serial number appearing on the front and a small camera lens below the text. The Solid Eye was destroyed along with Snake's OctoCamo Sneaking Suit in the microwave tunnel within Outer Haven.
The Solid Eye combined ENVG (Enhanced Night Vision Goggles) light amplification and imaging technology, and also allowed for binocular functionality (though not simultaneously). In addition, the NV capability could also reveal things that normally wouldn't be seen, such as footprints, thus allowing Snake an easier time predicting enemy route patterns and reacting accordingly. When heavy artillery such as tanks enter the field of view it displayed their specifications and armaments. It also takes in body temperature, heart rate and sweat secretion to calculate a soldier's physical and emotional state. Its camera vision utilized the fish-eye perception. Snake's model also acted as a corrective lens for far-sightedness.
Raiden also made use of a retractable dual Solid Eye system, which was incorporated into his headgear and worked in conjunction with his visor; the eye pieces were labeled with the text "caution /// dual solid eye system." By 2018, he had replaced the dual Solid Eye system with a single retractable eyepiece, labeled as an "artifical compound eye unit."
A similarly designed toy called Tobidacid was known to exist by Solid Snake, apparently having owned one at childhood, though Otacon was unaware of it.
Behind the scenesThe name of the Solid Eye is taken directly from the Solid Eye peripheral used with Metal Gear Acid 2. Apparently, Hideo Kojima took the name from the peripheral without telling the producer of Metal Gear Acid 2, who was "surprised" when he saw it in the original TGS trailer. The name is also a play on the term "naked eye," referring to unaided human visual perception, as well as being the partial namesake of Naked Snake.
The Solid Eye's writing on the front of the eye says:
"SOLID EYE SYSTEM
OTC • 0017/02"
A similar device appears in Metal Gear Solid: Peace Walker, called the Sonic Eye, which allows Big Boss to "sense" an enemy's path and location through soundwaves. In addition, the Analyzer has features similar to that of the Solid Eye, such as analyzing soldiers and the armaments and weaknesses of vehicles, including the classification and troop strength of the latter.
The Solid Eye also appeared in the official series website under Versus Battle, where it competed with FaceCamo.
Detects Everything on the Battlefield
Developed by Otacon and Sunny, Snake’s Solid Eye allows him to see, assess, & analyze nearly anything, near or far, day or night
METAL GEAR SOLID: THE LEGACY COLLECTION"
- ―Solid Eye description on Versus Battle
Dummied code in the PC version for Ground Zeroes indicated that the Solid Eye was planned to be in the game.