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Flickering lights in peripheral vision
August 19, 2008 12:00 PM   Subscribe

Why do lights flicker in my peripheral vision?

I've noticed in recent years that lights will appear to turn on and off in my peripheral vision and it's becoming more and more frequent. I'm a 28 year old female with no health problems and no medical insurance. I'll have insurance in about a month and will go to a doctor then, but I am wondering if this is something I should be really concerned about. I used to think they were "visual migraines" but haven't found a description of one that fits this.

In addition to the freakiness of it, it's really annoying cause I can never tell if it's really happening or just me. I constantly have to ask people if they are seeing the same thing. Usually they aren't.
posted by Raichle to Health & Fitness (16 answers total)
I can't quite tell from your description, but you might be having flashers (not the kind in trenchcoats), which are related to floaters and are associated with various goings-on with the vitreous fluid in your eye. They're usually harmless, though annoying, but can be associated with more serious conditions (I have a constant, heavy stream of floaters with occasional flashers, so I get checked periodically to make sure nothing's wrong with my retinas), so of course bring it up when you can see a doctor.
posted by scody at 12:21 PM on August 19, 2008

Peripheral vision is better at detecting flicker.

You might want to replace the fluorescent lights you are around often with more efficient electronic ballasts. From that article:

Fluorescent lamps using conventional magnetic ballasts flicker at twice the supply frequency. Electronic ballasts do not produce light flicker, since the phosphor persistence is longer than a half cycle of the higher operation frequency. The 100–120 Hz flicker produced by magnetic ballasts is associated with headaches and eyestrain.[2] Individuals with high critical flicker fusion threshold are particularly affected by magnetic ballasts: their EEG alpha waves are markedly attenuated and they perform office tasks with greater speed and decreased accuracy. The problems are not observed with electronic ballasts.[3] Ordinary people have better reading performance using high-frequency (20–60 kHz) electronic ballasts than magnetic ballasts.[4]
posted by robofunk at 12:22 PM on August 19, 2008

It would be worth talking to an opthamologist about this when you get your insurance. Could be an indicator of a lot of different things (I'm not sure if by flicker you mean something akin to flashes of light, or just irregularity in constant light sources). But if it's serious you should know sooner rather than later, and if it's not serious you should put your mind at ease.
posted by aught at 12:33 PM on August 19, 2008

Is there really a flickering light source? If you see a flicker that exists, then you're fine and perhaps above average in sensitivity, but if you see flickers that are ghosts, then you should worry about your retinas.

One way to check for flicker is to set a camera so that it takes longer to open and close the shutter, and slide the camera to the side as it takes a picture. The time dimension clobbers the x dimension and you can see the pulses across time. (Gods, I'm such a nerd.)
posted by cmiller at 12:36 PM on August 19, 2008

Robofunk has it right. The outer part of your retina (meaning your peripheral vision) has a different sensitivity to flickering stimuli than the fovea. This can manifest in the appearance of things flickering on and off when they're not in the center of your visual field.
posted by fake at 12:47 PM on August 19, 2008

If you complain to your employer (assuming it's a problem at work), point out that the electronic ballast replacement will pay for itself over time, especially if they are switch it from 40 Watt T12 lamps to 32 Watt T8 lamps. It will apparently also increases productivity.

I think it's a little strange that you are noticing the problem more frequently since a lot of buildings have switched to electronic ballast and T8 lighting since it pays for itself. I'm not even sure if it's legal to sell magnetic ballast fluorescent lamp fixtures anymore, as a result they have become less and less common. It may be a case of confirmation bias, you started noticing it, now you see it every time you encounter an old fixture.

This might help you however. If you stopped playing sports, video games, or something that qualifies as "motion training" then it may have contributed to your sensitivity to flicker. This study shows a marked improvement in critical flicker fusion when the participants had "motion training" 1 hr a day for nine days. You might consider getting back into a favorite sport or playing video games. Doctor prescribed video games of course.
posted by robofunk at 1:01 PM on August 19, 2008

It's definitely not the lights as it happens in every environment. I'll try to see an opthamologist but I doubt my insurance will cover it.
posted by Raichle at 1:30 PM on August 19, 2008

It's a little hard to explain but it looks like every light in a room shuts off and then turns back on. I'm not sure what to call it but flickering, but it usually will only happen once, very quickly, and then not for a few more minutes.
posted by Raichle at 1:32 PM on August 19, 2008

Ah, it's not a persistent flicker. This happens to me every once in awhile, I'm pretty sure it's normal. Sometimes I'm 100% sure it's a problem with the electricity grid because it's sometimes followed by a power outage or a computer reboots. Other times it seems like it's all in my head and no one else noticed. If you ask someone else if they noticed, it is possible that they blinked at some point during the outage and didn't notice it at all, or they just plain didn't notice. There are probably times when even you don't notice a power interruption because you blinked.

Now that we cleared up what it is you are experiencing I'm sure some people will add their two cents and say they experience the same thing. For whatever reason it reminds me of glancing at a wall clock and swearing the seconds hand just went in reverse.

Regarding the increased frequency, apparently outages like this can because by things like branches falling on power lines momentarily, major appliances turning on (AC, dishwasher), etc. It's possible that power companies in your area aren't maintaining the trees around their power lines as vigilantly as they used to. Or increased demand over the years in your area may have decreased the overall stability of the power grid so even relatively small things can cause a flicker.
posted by robofunk at 2:14 PM on August 19, 2008

Photopsia? Sorry couldn't find a decent link, there's some info here. I would definitely get this looked at.
posted by sero_venientibus_ossa at 2:56 PM on August 19, 2008

When you get on insurance, check and see if your opthamologist will take your medical. I paid $15 for copay for a regular check up and $15 for an HRT scan.

I haven't had any symptoms, but on my last visit, my doctor noticed a problem area in my right eye. I'm supposed to watch out for any increase in floaters and any problems with my peripheral vision, including flashing.

The HRT scan was me looking at a red laser for a minute and then a picture of my optic nerve was on the computer screen. The doctor drew a circle around my problem area so I could see the difference. I may have had it for years, or it may be something recent. I go back in December for a follow up.

So I would check it out when you can, a regular eye exam should be enough to start.
posted by lootie777 at 3:10 PM on August 19, 2008

My opthamologist to me to come in if I began to see flashes or flickers in my peripheral vision, as it's associated with glaucoma. Try to make an eye appointment.
posted by coppermoss at 3:11 PM on August 19, 2008

I've had flickery vision for years, just like the lights are turning on and off very rapidly. Only happens in very low light, and i've never been able to get to the bottom of it.

I've not had them for a while now, although in the past they've been very frequent, almost every night when i turned the light off at night.

I don't think it's anything too serious (touch wood!!)... although if they're getting more frequent it might be worth forking out a bit for a checkup.
posted by derbs at 4:06 PM on August 19, 2008

robofunk: I appreciate the help and all, but you are really not getting the fact that the lights are not actually going out. This is something brain/vision related. It just happened right now in my apartment and if all the power had flickered, I would have to reset clocks etc. My computer would have acknowledged it, etc. I am SURE that 98% of the time I see the lights flicker it's just me.
posted by Raichle at 6:58 PM on August 19, 2008

No problem, I still think it's nothing to be worried about. I should get checked (again) for glaucoma otherwise.

Computers and other electronics won't always be affected by power interruptions. They all contain capacitors that will hold a charge and keep the appliance functioning for a not insignificant amount of time after losing power. Power interruption can easily be long enough for a human to notice but not long enough for the computer, clock, TV, monitor, to skip a beat. Florescent lights on the other hand can be extremely sensitive to motors turning on. Since you are in an apartment I think it's even more plausible that something like a window mounted A/C unit in another apartment turning on is causing the flicker. Because the flicker from fully lit to dark is so abrupt, and our eyes have no time to adjust, in my experience the effect can be dramatic even if there is natural sunlight in the room.

If ever happened to me in broad daylight, then I would be worried.
posted by robofunk at 10:14 PM on August 19, 2008

My recommendation is to visit an ophthalmologist. It's easy for me to say because over here it would cost you little more than a boring afternoon of waiting in a public outpatient clinic, but someone really should look at your eyes (particularly the back of them) if you're having strange eye things. It might be nothing serious, and for what it's worth I've seen people with visual migraines that fit your description. However I've also seen people who go on to develop serious eye problems that begin with your symptoms.

A few questions: Is it in one eye or both (when it's happening, cover each eye one at a time to check)? Is it more prominent at night? Do you ever get 'floaters' that are like little semi-opaque shadows floating across your vision? Are these flashes associated with anything else such as a headache or sensitivity to bright lights? Has anyone in your family had eye problems, particularly retinal detachment, particularly at an early age?

Although my recommendation is to visit an ophthalmologist, in your current situation I'm sure it would be quite expensive and you probably won't do it until you change insurance. If it's just occasional flashes, not associated with anything else, and if it's not getting worse, you could probably wait a month but keep in mind this is a risk/benefit thing for you, it's not risk-free. I personally wouldn't wait, but I'm cautious about my eyes.

While you're very young for it, flashes can be a symptom of posterior vitreous detachment. This in itself is relatively benign, but it puts you at risk of retinal detachment and an ophthalmologist should review you to see if your retina is at added risk due to tears, etc. You may have none of these, but PVD is a diagnosis that a specialist would want to exclude.

If you get black spots in your vision, a shower of black dots, a curtain coming in from one side, distortion of your vision, or anything else that makes you think "this isn't right", go to an ophthalmologist or emergency department as soon as possible, definitely within 24 hours.

By the way, I'm not a doctor but I do have experience in this area. Take my advice with an appropriately-sized grain of salt, although I would take the paragraph above this one seriously.
posted by teem at 6:29 AM on August 21, 2008

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