The Ecto Monocle is a head mounted high tech scope that fits over one eye that can scan an entity or environment down to the sub atomic level. It is a kind of multi-tasking tool that can view an environment as it is, supernaturally speaking, and take readings in a similar function to the Ecto Goggles.
During the Infestation Incident, Egon Spengler used an Ecto Monocle to analyze an immobilized Zombie possessed by one of the Canine Poltergeists. After 15 minutes, the monocle's readings indicated the possession altered both the Poltergeist and Zombie on a subatomic level, creating a biological containment grid.
Egon used the Ecto Monocle in Seattle while investigating the charred remains of Charon's Patisserie and Pequod's. With the scan, Egon found trace levels of P.K.E. that would have taken years to build up. During the Chi-You incident, Egon used the Ecto Monocle to examine Casey Jones after he was freed from the ghost's control. Egon detected negligible P.K.E. readings and determined all signs indicated Casey would be alright. He continued wearing it while everyone conferred what to work on next. During the Proteus incident, Egon donned the monocle when he and the alternate Egon Spengler worked on boosting the yield of the Proton Grenades.
Egon used the Ecto Monocle to take readings in Lower Manhattan during a dimensional overlap. He used the Monocle to confirm Abby Yates' discovery of energized Ley Lines and also saw New York City Hall in an altered state.
- The Ecto-Monocle resembles the Helmet Mounted Display used by Apache Helicopter pilots. The Display comes with a clip-on-arm that drops a monocle in front of the pilot's right eye. The monocle in turns performs several functions, such as project a dozen or so instrument readings to save the pilot time. 
- The Ecto-Monocle's POV with night vision on is seen in Ghostbusters 101 #4.
- On page 11 of Ghostbusters 101 #4, in panel 3, the Monocle's screen bears Luis Antonio Delgado's 15 easter egg.
- Ghostbusters: Infestation #1
- Ongoing Series
- Volume One
- Teenage Mutant Ninja Turtles Ghostbusters
- Ghostbusters Get Real
- Ghostbusters 101