NeuroLogic is the third nonfiction book about the brain written by a Eliezer J. Sternberg who went to college at Brandeis, medical school at Tufts, and is now a Resident in Neurology at Yale University, Class of 2018.
The eighth and final chapter of NeuroLogic is tantalizingly titled, Why Can’t Split Personalities Share Prescription Glasses? – a bookend to the first chapter titled, What Do The Blind See When They Dream? Split personalities is the vernacular for Dissociative Identity Disorders, also referred to as Multiple Personality Disorders. It is a rare condition, to be sure, occurring in no more than 1 in 200,000 persons. Of course by persons we mean, individual bodies.
“Evelyn was in bad shape when she was admitted to the inpatient psychiatric unit.” This is the ominous opening to Chapter 8, introducing a patient who travelled the city with the help of a guide dog with no apparent cause for her legal blindness. Old files indicate that she had congenital blindness due to bilateral optic nerve injury, but there was no evidence of that. She had a traumatic upbringing with abuse at the hand of her biological mother and subsequently by foster parents and an older adoptive brother. At the age of eight her doctor arranged for her to transfer to a school for the blind. Evelyn’s visual acuity on a standard chart was 20/200, but when she switched to being 10 year-old Sarah she was 20/80. Four year-old Kimmy had a visual acuity of 20/60. Sternberg poses the question: How is that possible? After all, each personality had the same set of eyes.
We’re all fairly familiar with the notion of visual conversion disorder, essentially a first cousin of Streff Syndrome. Sternberg makes the linkage that Evelyn was most likely experiencing visual conversion reactions between her multiple personalities, but instead of it being a self-induced transient phase in response to stress, the conversion was being elicited under hypnosis by her psychiatrist. He writes: “The brain’s process of creating vision is much like that of creating identity. For one thing, the experience of vision is made up of component parts: distance, shape, color, size, and speed. They are all calculated by different parts of the brain and therefore have to be fused with ultimate precision.”
Here is a blog from Athanasios Komianos with citations showing that altered vision can vary in altered states including different VEP profiles and different spectacle Rxs. One of those references is a classic from Birnbaum and Thomann at SUNY Optometry. Remember the old adage: “It ain’t rare if it’s in your chair”.