Mumsnet has saved my sanity on a few occasions. Glad to be able to pay it forward!
OEI is at its most basic a form of trauma therapy but it can be used to affect just about any undesirable emotional state. Warning: it sounds terribly, terribly kooky!
However, it's based on neuropsychiatry - meaning, a science that integrates the brain's anatomy, physiology and chemistry (in other words, how the brain functions) with psychiatry (the study and treatment of emotional disorders). Which makes it sound a little more cool.
(Further explanation - I have experienced OEI from both sides. As a patient, so I can personally vouch for its effects. And in my professional life I do some co-treatment with several colleagues who are psychologists, in which we address the mind-body connection. So we work on people who have both physical and emotional "scars", so to speak, or people who have been so traumatized that their emotional problems express themselves as physical problems.)
What OEI is based on is that traumatic memories are stored in the brain's visual cortex. So when we remember a trauma, we see it again. And it's been shown that the eye movements of a trauma patient are extremely erratic and the eye tends to "glitch" or "get stuck" in a specific spot in the line of sight where the brain "sees" the trauma. This is mostly only figuratively speaking, in most cases, but not all, vision is not affected. However, there have been cases of patients who are so severely traumatized that their vision disappears in a specific eye position (presumably the one where the brain sees the most severe trauma).
Ok, enough explanations. Here's the nitty-gritty:
The most basic tool of OEI is "switching". Try this:
cover one eye, and observe how the world (or a specific person), or your current emotional state, feels to you. Then uncover the first eye, and cover the other one. How does the other side feel different to you? There is usually a difference in emotional intensity, especially when you feel fear, anger, sadness, inadequacy, whatever, very intensely on one side. So the switching procedure goes like this: cover one eye. If your "intense" eye is uncovered, you'l feel intense emotion hit you. Switch. The intensity should recede. When you feel better (usually 10-ish seconds, sometimes more, sometimes less), switch again and allow the intensity to rise. Switch quickly, so it doesn't overwhelm you. Switch back and forth several times. Over several switches, you should notice that the intensity of emotion decreases significantly, until you feel calm (or relatively calm, at least in comparison to before) while covering either eye.
I know - it sounds koooooooooooky!!! But what this is doing is integrating the visual cortices on both sides of the brain's hemispheres.
There is more to it than that, but this is at least something you can do yourself when you feel overwhelmed by sadness, anger, fear, inadequacy, memories of a trauma etc.
It does get more involved but for the rest, you need an OEI therapist.
Good luck!! Remember we're all here for you. If you find talk therapy isn't all you want it to be, venting on here is quite cathartic. Plus, most therapists won't make you laugh... and MN sure will!