Avulux Deep Dive

390 of your patients this year are going to have light sensitivity from migraines. The day I started writing this field note, I had three. Migraine photophobia is common, and the traditional answer is sunglasses or dark rooms. But sunglasses are too dark indoors and dark rooms make the pain worse later. FL-41 is another solution, but the color distortion and rose tint can be a turn off for some patients.

Avulux, therefore, is an appealing option for many: not too dark, minimal color distortion, and a gray-ish color. These specialty lenses got the head nod from the FDA at the end of August. Instead of a general wellness tool, it’s now a class 1 medical device to “treat light sensitivity in patients diagnosed with migraine.” 

I'll be honest, I've never prescribed Avulux lenses. I didn’t know much about them. But with the extra attention the company is getting from the FDA decision, I decided to read up on it. Here's what I found.

Light sensitivity from migraines is different. The main pathway starts with intrinsically photosensitive retinal ganglion cells (ipRGCs) in the retina. These send axons to thalamic areas, which then send afferents to pain receptors in the dura mater. Since the pain occurs in the dura mater, it can happen anywhere on the head and neck.

Here's a photo from one of the studies showing the variety of pain locations.

Like the rods and cones, ipRGCs have an opsin protein to absorb light, called melanopsin. Importantly, melanopsin is bistable. Think of it like an on-off switch. It has an "active" ready-to-fire state, and an "inactive" ready-to-reload state. When active, blue light (~480nm) flips melanopsin to its inactive state, and the ipRGC sends a signal to the brain. Melanopsin then either slowly relaxes back to its active state thermically or flips back via exposure to yellow light (~590nm).

Avulux directly targets these melanopsin wavelengths. With less blue and yellow light, less ipRGCs are sending signals, and less ipRGCs are reloading. Importantly, green wavelengths still get through. Oddly, green light does not exacerbate migraine photophobia as much as other wavelengths and can even be soothing at low light levels.

Shrug It should. There’s a small, independent Harvard study that says it does. But again, I have never prescribed it on any patients. I polled some of my colleagues from “OD’s on Facebook.” Here’s what they had to say:

Here’s my take based on the theory. It should work. But it shouldn’t do it all. Red light, for instance, seems to worsen pain, but doesn’t follow the same pathway outlined above. There may be higher-order, visual cortex processing that causes the sensitivity to light.

Also, the ipRGCs can be excited extrinsically by rods and cones. So colors outside the main melanopsin wavelengths can still activate the pain.

And lastly, it’s important to remember, Avulux does not treat migraines. It treats the light sensitivity associated with migraines. It doesn’t fix the headache, but makes it more tolerable.

What am I gonna do? For many of these patients, migraines cause them to miss work or strain social relations. They can devastate someone’s life with all the interruptions. Anything that can help, should be offered.

Side note: I do not get migraines. I rarely have headaches. But I wonder if these lenses could still be of benefit to me, too. ipRGCs are also at play with circadian rhythm. I live in a small apartment. At night, my family needs the lights on to socialize, but I want them off to wind down. So we leave them on. But if I put on Avulux lenses when the sun goes down, I wonder if they would help me wind down while keeping the lights on.

What do you think? Have you tried Avulux with your patients? Do you think it could help me wind down at the end of the day?

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