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Hysterical blindness is a condition in which patients lose their ability to see. The term "hysterical blindness" has fallen out of favor in recent years, and this condition is now officially referred to as a conversion disorder. Affected patients believe that they have an inability to see, while in reality their eyesight is physiologically preserved. Diagnosing the disease requires excluding other causes of vision loss. Treatment typically relies on addressing any underlying psychological distress.
The symptoms of this condition come on suddenly. Patients describe a loss of vision in a portion of one eye, in the entirety of one eye, or in both eyes. Sometimes the loss of ability to see can be accompanied by other deficits, such as the inability to move half of the body. Often patients express a lack of concern over their ability to see.
Making the diagnosis of hysterical blindness typically requires an ability to fully understand the patient's emotional states and the recent events in their lives, and it also requires performing a nuanced physical exam. Often the symptoms are triggered by emotional distress. Although patients report an inability to see, in reality, no neurological deficits are present. The pupils of their eyes are able to constrict in reaction to light or when focusing on objects located close by. Physicians or other health care professionals might note that patients blink if an object is rushed towards their faces, and might squint when asked to look at an object far way; in some cases the patients might be observed to be reading or watching television when they think they are not being watched.
Typically, this condition is thought to be a diagnosis of exclusion. In other words, other more serious medical conditions should be ruled out before assuming that a patient has this condition. Patients who have had damage to the parietal lobes of their brains could have similar symptoms. A condition called multiple sclerosis can cause short-term neurologic deficits, and is another of the diagnoses that should be considered before diagnosing hysterical blindness.
Treatment of hysterical blindness focuses on alleviating any underlying psychological stress. Patients might benefit from psychotherapy, where they talk to a trained therapist about their thoughts and experiences. Medications to treat co-existing depression or anxiety could be used. Some psychiatrists and psychologists have also used hypnotherapy as an approach towards recovering patients' belief in their ability to see, although the use of this technique is not well-proved or fully accepted.
I am reminded of The Who's "Tommy," who apparently suffered from this condition after seeing his stepfather kill his real father, coming back from the war. "You didn't see anything," his mother and stepfather tell him repeatedly -- and he doesn't.
I am curious how often this happens, and when it does, how long it normally takes the person to recover.