Neural Response To Flicker Rates: Artificial Light Causes Myopia?

We’re going to go serious on some full-on hardcore science, today.  Neural activity and all the whatnots.  Pull up your sleeves, for this one.

Artificial-anything should be suspect, when it comes to your biology functioning correctly.

We already figured this out.  Often I think of artificial as equals = incomplete.  We know this about food.  We don’t (people in general) know this about light.  And without going over the edge here with hippie fruit loop talk, light is the food of our eyes, my darling shanty kittehs.

“Light Is The Food Of Our Eyes”

– Eyeguru Jake-omm Shanti-steiner, 2016

There is sometimes an ounce of truth, in some of the fruity hippie talk.

An ounce.  In this case, let’s talk about fluorescent light – or as I like to call it, the suck-your-soul light.  Or the ‘get these out my face’, light.  Let’s put aside jokes and the fluff of hippie talk, and dig into some hard science on the dangers of artificial light.

Ready?  Exhibit A:

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“Myopia induced by flickering light in guinea pigs: a detailed assessment on susceptibility of different frequencies”

Int J Ophthalmol. 2013; 6(2): 115–119. 
Published online 2013 Apr 18. doi:  10.3980/j.issn.2222-3959.2013.02.01

AIM

To investigate the effectiveness and feasibility of inducing myopia in guinea pigs by flickering light (FL) stimulation with different frequencies.

METHODS

Seventy 2-week-old guinea pigs were randomly assigned to six groups: five FL groups and a control group (n=12 for each). Animals in the five FL groups were raised under 500lx illumination with a duty diurnal cycle of 50% at a flash rate of 5, 1, 0.5, 0.25 and 0.1Hz respectively. Those in the control group were reared under steady 250lx illumination. Refraction, axial length, and radius of curvature were measured before and at 2, 4, 6, 8, 10 and 12 weeks after treatment. At week 12, the eyeballs were taken out and three ocular dimensions and dry weight of sclera were measured.

RESULTS

A myopic shift and axial eye length increase developed in the five FL groups. Stimulation at 0.5Hz caused greater changes in myopic shift, axial elongation, eyeball dimension, and dry weight of sclera than stimulation at other frequencies. Compared with controls, eyes in 0.5Hz group were approximately -5.5±1.5D more myopic with increase in horizontal, vertical, axial dimensions by 0.89±0.3mm, 0.69±0.2mm, 1.12±0.2mm respectively and with increase in dry weight of sclera by 0.44mg.

CONCLUSION

Chronic exposure to periodic illumination at temporal frequency is attended by development of excessive ocular enlargement and myopic refractive error. Emmetropization could be disrupted differently by frequency alteration.

Here’s the whole study.

Now, caveat.  Fluorescent lights don’t flicker at a half hertz (rather at least double of the ballast if connected direct to AC power, or closer to 120Hz, similar to incandescent-also-crap light).  That’s a whole lot faster flicker rate, and potentially less significant of a direct risk of myopia development.

So on one side you could say, that study, doesn’t say myopia can be caused by fluorescents.  On the other hand you might say, living your life under flickering light, possibly not a great idea considering measurable impact of flicker on myopia development.

flicker-image5

What could go wrong?

Let’s dig a little further, into available science on this topic.

This next study is tantalizingly titled,

“Modulation of fluorescent light: flicker rate and light source effects on visual performance and visual comfort”

I picked out one little text-bite to get fellow science nerds interested.  Here:

“Low-frequency flicker (on the order of 120-150 Hz; cf. Ref. 14) may add extra noise to the neural activity. This noise, which has the same temporal code as the signal to be interpreted, may inhibit object or form identification by interfering with the integration of neural responses from the various neurons that respond to the specific stimulus features. The additional synchronous neural activity (noise) would therefore impede stimulus recognition, especially if the object is difficult to see, or is near threshold. In the present experiment, a large effect occurred for Landolt rings of luminance contrast .21, but not for darker rings. (The absence of a significant effect for contrasts below .21 may be an artifact of the higher variability of performance on those rows.)

Furthermore, the demands of processing this extra neural noise might translate into asthenopic(2)symptoms, such as increased eye-strain and headache.”

 Gets deep quick, doesn’t it.

We have two categories of readers, here at @endmyopia.  One category is the give-me-the-answers, don’t-bore-me-with-nerd-talk.  And the other category is the opposite.  If you are that second group, here is the full PDF of this rabbit hole of a neural activity response to low frequency flicker study.

Enjoy!

If you don’t want to read all that, let’s leave at where we always leave it.  Go outside.  Use as much full spectrum, natural light in your eyes-open environment, as possible.  Don’t trust the lens-sales pitch.

You probably notice that the bias of this blog is mainly to keep things on the light side, on the tangible, actionable side, on the actual participant feedback side.  Because that’s what I want you to do, is get your eyes back, and get on with life.  This isn’t meant to turn into an obsession about for-profit conspiracies, or science-quote battles.

But then sometimes, we’ve got to bring out the big guns.   I want you to have these tools, so you could confidently argue the side of natural myopia control with any ‘professional’ … “Oh yea, big boy?  You want to go?  Tell me what you think about these flicker rates and neural response, then”.  😉

Really though, use what you learn here to enjoy life.  Think positive, and avoid the nay-sayers, and argument starters, and dogma accepting, fancy titled opponents to simple, natural answers to the myopia problem.

Cheers, hopefully this blog post is finding you well and eyes happy.

-Jake

2016-11-09T02:18:07+00:00 By |Categories: Science|