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B.T. was a woman in Germany who had been blinded in an accident when she was 20. At 33, she began seeing a therapist for her dissociative identity disorder, a controversial diagnosis that used to be called multiple personality disorder. Four years into their sessions, a strange thing happened: Some of those personalities — but not all — began to see. Her case is described by her physicians in a recent issue of the journal PsyCh, which Brain Decoder covered earlier this month.

The patient: B.T. had been told by her doctors that her blindness had been caused by brain damage from the accident in her early 20s. “But years later, during psychotherapy treatment for her psychiatric disorder, she began to switch between blind and sighted states,” writes Agata Blaszczak Boxe for Brain Decoder. At first, her sight was limited to just one personality out of more than 10, but as she worked with her therapist, “she almost entirely regained her ability to see.”

The diagnosis: Her case may be an example of psychogenic blindness, which is itself an example of a conversion disorder — a physical malady (such as blindness, but also paralysis or other ailments) that cannot be explained by physiological damage. But that doesn’t make the symptoms any less “real,” according to the U.S. National Library of Medicine:

People who have conversion disorder are not making up their symptoms (malingering). Some doctors falsely believe that this disorder is not a real condition and may tell people that the problem is all in their head. But this condition is real. It causes distress and cannot be turned on and off at will.

Cases of conversion disorder sometimes follow some traumatic event, and may be the result of the patient’s attempt to resolve their conflicting emotions about what happened to them. Boxe suggests that B.T.’s case may be explained by “selective attention — that is, somehow, the attention system completely ignores the visual information sent to the brain.”

This is essentially what happened in another recent case of psychogenic blindness reported in the Ethiopian Journal of Health Science earlier this year: A young woman was unable to see for several days following a traumatic event, but regained her sight through therapy. Likewise, B.T. slowly regained her ability to see, too. The line between the physical and the psychological is often blurrier than we might imagine.