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We Asked an Optometrist Why MDMA Makes Your Eyeballs Shake

As any devotee to the /r/drugs subreddit will be able to tell you, eye wiggles – or nystagmus – are a real and mysterious hassle.

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It all usually starts at around 01:00. You've reached that point, a few dabs or bombs in, when it's suddenly a great idea to text your ex-housemate. It's time to tell them how much you love them, how much you miss them, and that you wish they were right here with you, stroking people's faces at the rave/house party/unnecessarily long dinner party.

But when you look at your phone to send the text, the apps are hopping across your screen like mad. You remember what your eyes were like, back when they worked a couple of hours ago, and none of this was part of the deal. Opening and closing them doesn't stop it either, FYI. Instead you may struggle to fixate on bright lights, or your eyes may feel like they're jerking sideways. Welcome to the ecstasy eye wiggles – or, as sometimes diagnosed online, nystagmus.


That's not to be confused with acquired nystagmus, which is usually caused by a head injury. This is that involuntary, quick-flickering-eyes feeling, well-known to the kinds of people who ask the /r/drugs subreddit if this is totally fine or if they're dying. It's nothing new, though. A forum post from as far back as 1999 sees a user describe a pill that gave them "gave me the most intense eye wiggles I have ever experienced. Sometimes I couldn't see and I thought i was going to fall over," they continue, "but I could feel my eyes flickering back and forth so fast that I could see two or three of everything."

I figured it would be worth asking someone who understands how eyes work and just how much involuntary nystagmus can affect the body. So I got in touch with an expert – Dr Matt Dunn, an optometrist and lecturer in visual perception at the University of Cardiff – to chat about eye wiggles, how our body creates them and what their long-term effects could be.

VICE: Hi Dr Dunn, can you tell me why our eyes wiggle when we take MDMA?
Dr Matt Dunn: There are reports of nystagmus occurring with MDMA but no direct studies have been done looking at it specifically. Having said that, there are reports of other drugs – things like cocaine, for example – causing something called opsoclonus, which isn't quite nystagmus but it's very similar. I've found some videos on YouTube and it looks to me more like what you would call opsoclonus. In this case, it's not technically nystagmus but these things are very similar: they're involuntary wobbles of the eyes.


We know why opsoclonus happens. There's a population of neurons in the brain stem called omnipause neurons, which exist to allow us to make quick eye movements. So when you move your eyes, you make rapid movements called saccades. In order to do that, you use neurons in the brain stem that are normally active, and which stop the eyes from oscillating back and forth.

Normally, those neurons allow you to make a focused rapid eye movement to a new target. But when omnipause neurons are turned off, you we get these rapid back-to-back oscillations – the saccades. So that's what it looks like is going on.

What are the wobbles doing that make it so hard to focus on something like a smartphone screen when you're really high?
Well, if your eyes are moving uncontrollably, then you will find that it's difficult to focus on what you're trying to see. We often forget how focused our vision is. You've got about two degrees of visual space, at the very centre of your eyes, in an area packed with cones called the fovea. If you hold your hand out at arm's length and look at your thumbnail, it's about that size; a dense area of photo receptors. So that's all you've got to do your reading and your focused visual tasks.

Zooming out, everything in your peripheral vision isn't quite as detailed as that. Although we have the illusion that everything looks clear all the time in fact we're only really seeing clarity in the middle. So when your eyes uncontrollably start moving around in different directions, then you become aware of the fact you're unable to look at something that you want to see because your vision is only clear in that central area. And if you are then unable to focus your central vision on the object you're looking at – like something on your phone screen – it'll be really hard to see.


Does MDMA affect the muscles attached to your eyes and make them wiggle?
It's speculation. No specific studies have looked at it. An educated guess would stipulate that what's happening here is within the brain itself. So the muscles would just be an effector in that long neurological chain. If there was a feedback loop in the brain, then it's causing that motor signal to be passed out to the muscles. All you're seeing there are the muscles doing the job they're told to do. It's just not the appropriate response.

If your eyes wiggle, does that mean you've taken a good pill? People speculate about that a bit when talking about this.
That's hard to know, really. Is that something desirable? Probably not. There are people who are affected by nystagmus constantly. Many people develop this after birth. It's a very debilitating condition. Other people will get nystagmus later in life in response to an injury or multiple sclerosis, things like that. And then they have uncontrollable eye movements for the rest of their life. Now they're not quite the same as what it would appear as we're seeing here. They're still uncontrollable eye movements and they're not very desirable at all. I can't imagine it being construed as a good thing!

Can the wobbles physically damage our eyes?
I cannot see any specific reason why it would. In people who have nystagmus, we find that over long periods of time, they can sometimes develop an astigmatism – or distorted images – in the eye. This amounts years and years of constantly having the wiggles every waking moment of your life. I should imagine it's unlikely to cause permanent damage to the eye from short durations like this, from recreational drug use.


Could eye wiggles last for ever?
In some people, that is the case. Although, I'm not aware of any reports where it'd been induced by MDMA. It's usually in response to a serious brain injury of multiple sclerosis. It's not out of the question.

But once they've started, is there a way to stop eyes from wiggling like this?
Presumably, if it's something affecting the fundamental level of the brain stem related to consciousness, I would imagine probably not. It does sound to me as though if that's happening, that's someone overdoing it somewhat!

One thing worth mentioning is there are some people who can do this voluntarily. They have this ability; on command they can make their eyes wobble at anytime when they're asked to. Is that a very desirable thing? I can't imagine it would be.

Thanks, Matthew.


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