A man’s first eye exam at a new eye clinic revealed something surprising and curious: his iris appeared to be glowing. No, he wasn’t secretly possessed by Sauron, Sith, Voldemort, or Captain Marvel, but he did, it turns out, have a very rare disorder.

A new case report published in the New England Medical Journal describes how the man, in his mid-forties, had just moved to a new area and so had set up an appointment with a new eye doctor.

There was a history of glaucoma – a disease that damages the optic nerve, which connects the eye to the brain – in his family, and he had already been diagnosed with high eye pressure and was taking medicine to reduce it, thus the priority of re-establishing care.

When the doctor performed the eye exam, shining a bright light at the eye like most of you will have experienced, they discovered “circumferential spoke-like iris transillumination” in both eyes.

The iris is the colored circular structure around the pupil that dilates and contracts, controlling the amount of light that reaches the retina. In this case, the light was shining through the iris due to a lack of pigmentation. It’s a defective characteristic often found in albinism, though not exclusively.

With iris transillumination, the iris is translucent, allowing light to pass through, which then bounces back off the edges of the optical lens, making it visible to the person shining the light into the eye and causing the Dark Phoenix-esque glow. This is also how one-way glass used in police interrogation rooms works.

The report authors diagnosed the man with pigment dispersion syndrome – a disorder that occurs when pigment sloughs off from the back of the iris and floats around, eventually accumulating in the anterior chamber (the bit between the iris and the cornea’s innermost surface), and clogging the eye’s drainage system.

Your eyes maintain pressure by producing a fluid called aqueous humor. As this flows into your eyes, the same amount should flow out, but if it gets clogged, like in this instance, and the fluid doesn't leave the eye, it builds up pressure. This can damage the optic nerve and, in about 30 percent of cases, can lead to pigmentary glaucoma.

Pigmentary dispersion syndrome is pretty rare, and usually occurs in people in their twenties to forties, which is younger than other types of glaucoma. Though it occurs in men and women in equal numbers, it is three times more likely to develop into glaucoma in men.

It can be treated with both eye drops and laser surgery, which is what the patient opted for. He underwent selective laser trabeculoplasty to drain fluid from the eye and continued to use his existing pressure-lowering eye drops.

If you have a history of glaucoma in your family, visit your health care provider for advice and treatment.