An extreme case of “fussy” or “picky” eating caused a young patient’s
blindness, according to a new case report published in Annals of
Internal Medicine.
The University of Bristol researchers who examined the case recommend
clinicians consider nutritional optic neuropathy in any patients with
unexplained vision symptoms and poor diet, regardless of BMI, to avoid
permanent vision loss.
Nutritional optic neuropathy is a dysfunction of the optic nerve which is
important for vision. The condition is reversible, if caught early. But, left
untreated, it can lead to permanent structural damage to the optic nerve and
blindness.
In developed countries like the UK, the most common causes of nutritional
optic neuropathy are bowel problems or drugs that interfere with the absorption
of various important nutrients from the stomach. Purely dietary causes are less
common because food supply is good, but elsewhere in the world, poverty, war
and drought are linked to malnutrition and higher rates of nutritional optic
neuropathy.
Clinician scientists from Bristol Medical School and the Bristol Eye
Hospital examined the case of a teenage patient who first visited his GP
complaining of tiredness. The link between his nutritional status and vision
was not picked up until much later, and by then, his visual impairment had
become permanent.
Aside from being a “fussy eater,” the patient had a normal BMI and height
and no visible signs of malnutrition and took no medications. Initial tests
showed macrocytic anemia and low vitamin B12 levels, which were treated with
vitamin B12 injections and dietary advice. When the patient visited the GP a
year later, hearing loss and vision symptoms had developed, but no cause was
found. By age 17, the patient’s vision had progressively worsened, to the point
of blindness. Further investigation found the patient had vitamin B12
deficiency, low copper and selenium levels, a high zinc level, and markedly
reduced vitamin D level and bone mineral density. Since starting secondary
school, the patient had consumed a limited diet of chips, crisps, white bread,
and some processed pork. By the time the patient’s condition was diagnosed, the
patient had permanently impaired vision.
The researchers concluded that the patient’s ‘junk food’ diet and limited
intake of nutritional vitamins and minerals resulted in the onset of
nutritional optic neuropathy. They suggest the condition could become more
prevalent in future, given the widespread consumption of ‘junk food’ at the
expense of more nutritious options, and the rising popularity of veganism if
the vegan diet is not supplemented appropriately to prevent vitamin B12
deficiency.
Dr Denize Atan, the study’s lead author and Consultant Senior Lecturer in
Ophthalmology at Bristol Medical School and Clinical Lead for
Neuro-ophthalmology at Bristol Eye Hospital, said: “Our vision has such an
impact on quality of life, education, employment, social interactions, and
mental health. This case highlights the impact of diet on visual and physical
health, and the fact that calorie intake and BMI are not reliable indicators of
nutritional status.”
The team recommends dietary history should be part of any routine clinical
examination like asking about smoking and alcohol intake. This may avoid a
diagnosis of nutritional optic neuropathy being missed or delayed as some
associated visual loss can fully recover if the nutritional deficiencies are
treated early enough.
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