A case highlights a little-known fact about a poor diet: In addition to being tied to obesity, heart disease and cancer, they can also permanently damage the nervous system, particularly vision, according to a report published in the journal Annals of Internal Medicine.
A teen who ate nothing but fries, chips and other junk food for years slowly went blind. The teen's problems began at age 14, when he went to the doctor's office complaining of tiredness. The teen was reportedly a picky eater, and blood tests showed he had anemia and low levels of vitamin B12. He was treated with injections of vitamin B12 along with advice on how to improve his diet.
However, by age 15, he developed hearing loss and vision problems, but doctors couldn't seem to find the cause—results from an MRI and eye exam were normal. Over the next two years, the teen's vision got progressively worse. When the boy was 17, an eye test showed that his vision was 20/200 in both eyes, the threshold (起始点) for being "legally blind" in the United States.
Further tests showed the teen had developed damage to the optic nerve (视神经). In addition, the teen still had low levels of vitamin B12, along with low levels of selenium (硒) and vitamin D. These deficiencies caused doctors to ask the teen about the foods he ate. "The patient admitted that, since elementary school, the only things he ate had been fries, chips, white bread, processed ham slices and sausage," the authors from the University of Bristol in the United Kingdom wrote in the report.
This kind of vision loss is potentially reversible (可逆的) if caught early. However, by the time the teen was diagnosed, his vision loss was permanent. What's more, wearing glasses would not help the teen's vision, because damage to the optic nerve cannot be corrected with lenses, said the study lead author Dr. Denize Atan.
