I've been having some issues with my eyes, and while idly consulting Dr. Google I came across this rather good article, not just on optic neuropathy but B12 deficiency in general:
Eyes/Very interesting article - Pernicious Anaemi...
Eyes/Very interesting article
Thanks for posting that. A great teaching example on the importance of determining the cause of a B12 deficiency before stuffing the patient full of useless B12 tablets and harmful folic acid tablets.
But it also includes a description of how a B12 deficiency can cause optic nerve neuropathy, not because of damage to the myelin sheath, but by depletion of ATP. I knew I'd read something about this but I couldn't find the reference. Thanks again.
What does ATP mean please. I am unable to try and read the article again.
Thanks
.
ATP is adenosine triphosphate. It is a molecule that the body uses for energy storage.
ATP has three phosphate groups. When you remove one (to form ADP) it releases energy, that the body can use for various purposes. When you add a phosphate to ADP it uses up energy.
In the body Krebs cycle reacts glucose with oxygen in a series of steps to make water and carbon dioxide - and a lot of energy. Much of that energy is used to make ATP.
As well as glucose, other molecules can enter the Kreb's cycle to make ATP. One of these is succinyl CoA. Which is made from some fatty acids and some amino acids. Adenosylcobalamin in important in the formation of succinyl CoA from methylmalonyl CoA.
Without enough B12, the body cannot make enough adenosylcobalamin, so it cannot convert enough methylmalonyl CoA to succinyl CoA and the end result is that the body cannot make enough ATP from some fats and amino acids. So the body cannot use those as effectively as energy sources, like normal people do,
Wow! That poor 63 year old man ....
"The patient’s medical history was positive for obesity, nicotine dependence, gouty arthropathy, mild carotid artery stenosis, throat cancer and stomach ulcer. He was status post a December 2004 resection of an oropharyngeal tumor and neck dissection. The stomach ulcer was treated with gastric surgery, date unknown, with resultant pernicious anemia. His current medications included allopurinol 100 mg daily, cyanocobalamin 1000 mcg/mL intramuscularly monthly...",
... could almost have been me apart from the "obesity, nicotine dependence, gouty arthropathy, mild carotid artery stenosis, throat cancer" as I had gastric surgery in 1959 was diagnosed with P.A. as a result in 1972 after two "Schilling tests" and I'm still "clivealive" aged 78.
My then doctor, having put me on cyanocobamalin 1mg every four weeks, told me that my eyes would be "regularly examined" but whenever I asked the succession of nurses down the following 47 years of their giving the injections "look into my eyes" they said they knew nothing about that. Hey Ho!
In 2015 when diagnosed with type 2 diabetes I immediately had a "diabetic eye screening test" (retinography) which reported "you do have some background retinopathy i.e. changes to the blood vessels at the back of your eye" .
I wonder whether this too was caused more by the P.A. than the "new" diabetes.
It is worthy of notice that the "authors" of the article Amber R. Scharnweber, OD, FAAO, ABCMO, and Richard J. Zimbalist, OD, FAAO appear to have a better understanding of P.A.?B12 Deficiency than a good number of GPs.
Thank you Curlygal for sharing
Thank you . That was very interesting.
I felt like my eyesight was deteriorating rather quickly compared to my 3 sisters, and so, once diagnosed with B12 deficiency, asked my optician about B12 deficiency and eyesight. He showed me online what the back of the eye might look like if affected by B12 deficiency, and now always checks the back of my eye just to reassure me. Although I have to wear varifocals permanently now, last time I was checked, no deterioration was noticed and that's a first.
I don't get "shivery" eyesight now, which used to happen when really tired. I assumed that this was muscle atrophy, which affected my legs and arms especially when really deficient. All of this has gradually improved- sometimes difficult to remember symptoms years later- although propping myself up at the bus-stop in the mornings on the way to work difficult to forget.
A very good reason to record symptoms, frequency and severity long-term, especially if memory loss is an on-going problem. More importantly, slow improvement is very difficult to notice unless recorded over months and years. It can continue for longer than many people (including some consultants) can imagine.
Don't give up, Curlygal .
Thank you 😊
I visited the optician on Friday, apparently the problem with my vision is not typical of B12 deficiency and my eyes are healthy. However, my prescription has changed (in one eye only) by a full dioptre in only 8 months, which is very unusual. I've been getting blurred vision which varies from day to day. Lenses don't fully correct the defect either. So she's writing to my GP so they can do some blood tests. It could be diabetes (I doubt it because my diet is good and I don't eat much sugar). I'm puzzled. It's all a bit weird. And I've to go back in 3 weeks to get my eyes tested again.
Good that they're straight on it, Curlygal - and let us know what they say.
In the meantime try not to worry too much, stress being a bit of a B12 depleter !