Having a poor diet leads to many other chronic illnesses. But now researchers from the University of Bristol believe that the same may be true for eye disease as well.
In an extraordinary case report published in the journal Annals of Internal Medicine, researchers say that a patient has suffered from optic neuropathy after years of having a limited diet of chips, crisps, white bread, and some processed pork.
Optic neuropathy occurs when the nerve cells which transmit visual information to the brain become abnormally short. These cells are called retinal ganglion cells. When this occurs, the neurons which control the sight are no longer functioning properly, or when the nerve cells die, the optic nerve is no longer able to send information to the brain.
The onset of optic nerve neuropathy varies in children. In some cases it is asymptomatic, and the affected person has perfect vision in the dark without any trouble. In other cases, the illness is life threatening and the affected person is completely blind because the nerves leading to the optic nerve are no longer working properly. The condition is reversible, only if caught and treated early.
Nutritional deficiencies such as nutritional optic neuropathy affect more than 2 billion people globally, and they have a high prevalence in developing countries, especially where a growing population will be particularly poor and where the food supply remains fragile.
The condition, however, is rarely seen in people in developed countries because of good food supply, and when it appears, it mainly stems from malabsorption (where the digestive system imperfectly metabolizes absorbed nutrients), taking drugs and having poor diet.
The case of a teenage patient who suffered from vision loss after years of bad dietary habit became known following a visit to his GP complaining of tiredness. Initial test showed he was anaemic and had low vitamin B12 levels, so he was given vitamin B12 injections and dietary advice.
The patient also confessed that he had been a picky eater, but aside from that, his BMI was normal, he showed no signs of malnutrition, and didn’t take any form of medication.
Then a year later, the patient had developed vision symptom and problems with his hearing. By the time he turned 17, he was diagnosed with optic neuropathy. Tests revealed the cause was entirely nutritional.
The patient also had several micronutrient deficiencies – including low copper and selenium levels, and low vitamin B12, which means the injections no longer worked. He also had high zinc levels, and conspicuously low vitamin D levels, which explains his low bone mineral density.
The onset of nutritional optic neuropathy, as the researchers concluded, resulted from the patient’s ‘junk food’ diet and limited intake of nutritional supplements. The condition could become more prevalent in the future, given the widespread consumption of junk food at the expense of food that is more nutritious, and the rising popularity of veganism.