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B12 Deficiency Eyes: Symptoms, Blurred Vision, Dry Eyes and Floaters
With B12 deficiency, eyes are affected mainly through damage to the optic nerve. This causes painless blurred or dim vision in both eyes, a blind spot near the centre of vision and washed-out colours. If it is treated early, vision often recovers; if it is left for months, the damage can become permanent. Evidence for dry eyes is limited, and no established link with floaters has been found. B12 deficiency is diagnosed with a blood test and treated by your doctor; an eye examination checks the optic nerve and rules out other causes.
How does vitamin B12 deficiency affect the eyes?
Vitamin B12 (cobalamin) keeps nerves healthy and helps make red blood cells. The body can store B12 for 2 to 5 years, according to the NHS, so a deficiency usually builds up slowly and the first signs can be easy to miss. The NHS lists "problems with your vision" among the symptoms, alongside extreme tiredness, pins and needles, a sore red tongue, and memory or balance problems.
The effect of vitamin B12 deficiency on the eyes is best understood in three parts:
- The optic nerve (well established). The optic nerve carries images from the eye to the brain. Without enough B12 it can become damaged, a condition called nutritional optic neuropathy.
- The surface of the eye (limited evidence). A few clinical studies and case reports link low B12 with dry, painful eyes.
- Floaters (no established link). Floaters come from the gel inside the eye, not from the nerve.
A systematic review of case reports in the journal Annals of Medicine and Surgery (2020) notes that B12 deficiency rarely shows up first with visual symptoms. So if you have blurred vision, B12 is rarely the first cause to suspect, but it is an important and treatable one to rule out, especially if you also have other B12 symptoms.
B12 deficiency and blurred vision: what does optic nerve damage feel like?
Blurred vision from B12 deficiency is typically a slow, painless loss of sharpness in both eyes at the same time. According to EyeWiki, the clinical encyclopedia of the American Academy of Ophthalmology (AAO), nutritional optic neuropathy causes bilateral, symmetrical, painless visual loss with a central or centrocecal scotoma (a blind or hazy patch around the point you look at), reduced colour vision and reduced contrast sensitivity.
In everyday terms you might notice:
- text going blurred or dim even with the correct glasses, in both eyes
- a smudge or gap in the middle of what you look at, while side vision stays normal
- colours looking faded
- reading and recognising faces getting harder over weeks to months
| Sign | What it means | Why it points to the optic nerve |
|---|---|---|
| Both eyes affected | Symmetrical loss of sharpness | The deficiency affects both nerves |
| No eye pain | Vision fades without pain | Nutritional damage is painless |
| Central blind spot | A patch of missing or hazy vision at the centre | A central or centrocecal scotoma is the typical field defect |
| Faded colours | Colours look washed out | Reduced colour vision is a typical feature |
| Normal-looking eye | Usually no redness or discharge | The problem is behind the eye, not on its surface |
An eye doctor may find that the optic discs look normal or slightly swollen at first, then pale on the side nearest the macula as damage progresses, with thinning of the nerve fibre layer on scans. Because both eyes are affected symmetrically, there is typically no difference in pupil response between them (no relative afferent pupillary defect), which can make it easier to miss on a quick check.
Important: blurred vision has many causes: a change in glasses prescription, cataract, dry eyes, retinal or macular disease, diabetes and migraine among them. B12 is only one possibility, which is why an eye examination matters.
B12 deficiency and dry eyes: is there a link?
There may be a link in some people, but it is not firmly established. Dry eye is extremely common and usually has other causes, such as screens, ageing, contact lenses, blocked eyelid glands or medicines. Research on B12 and the ocular surface is still limited:
- A clinical study in Graefe's Archive for Clinical and Experimental Ophthalmology (2017) evaluated vitamin B12 deficiency in people with severe dry eye and neuropathic ocular pain (pain from irritated corneal nerves) and concluded that B12 deficiency is relevant to their symptoms.
- A 2022 literature review in Acta Biochimica Polonica concluded that B12 supplementation helps sensory nerves regenerate and can relieve pain in some eye conditions, including dry eye.
- A 2023 case report in the Journal of Neuro-Ophthalmology described a person on a very restricted diet who had both dry eye and optic neuropathy from multiple vitamin deficiencies.
- A 2026 systematic review in Ophthalmic and Physiological Optics on oral vitamins in dry eye disease notes that vitamins play an important role in keeping the ocular surface healthy.
What this means for you: if you have persistent dry or burning eyes, especially with other B12 symptoms such as tingling, fatigue or a sore tongue, mention it to your doctor and consider a B12 blood test. Taking B12 supplements on your own is not a proven treatment for ordinary dry eyes. Dry eye is best treated according to its cause, and allergy and dryness are often confused: see our guide to eye allergies: symptoms and treatment if itching and redness are part of the picture.
B12 deficiency eyes and floaters: what is the truth?
No established link between B12 deficiency and floaters was found in the sources checked for this page. Floaters are the specks, lines or cobwebs that drift across your vision. According to the AAO, they are tiny clumps of gel or cells inside the vitreous, the jelly that fills the eye, and what you see are their shadows on the retina. They develop mostly with age, as the vitreous thickens and shrinks, and are more common in people who are short-sighted, have had cataract surgery or have had eye inflammation.
That matters because floaters can also signal an emergency. See an ophthalmologist the same day if you notice:
- a sudden increase in floaters
- many flashes of light
- a shadow in your side vision
- a grey curtain over part of your vision
The AAO says these can be signs of a retinal tear or detachment, which needs urgent treatment. Do not put new floaters down to a vitamin deficiency without having your retina checked.
Can vision come back after B12 treatment?
Often yes, if treatment starts early. EyeWiki reports that visual acuity improves first, then colour vision, once B12 is replaced. The outlook is poorer when treatment is delayed more than about 3 months after diagnosis, or when vision has already fallen to 20/400 or worse. The NHS also warns that nervous-system problems from B12 deficiency can sometimes be permanent, and that some problems may be irreversible if the deficiency is left untreated.
The practical message: do not wait to see whether blurred vision "settles". A blood test is quick, and early treatment gives the nerve the best chance.
What causes B12 deficiency and who is at risk?
Pernicious anaemia, an autoimmune condition in which the body cannot absorb B12 from food, is the most common cause of B12 deficiency in the UK, the NHS says. Other causes and risk factors:
- Diet: a vegan diet without B12 supplements or fortified foods, and, less often, a very restricted diet.
- Medicines: proton pump inhibitors (acid-reducing tablets), metformin (a diabetes medicine) and nitrous oxide ("laughing gas").
- Stomach or bowel conditions or surgery: for example gastrectomy or Crohn's disease.
- Age: the NHS reports that vitamin B12 or folate deficiency affects about 1 in 20 people aged 65 to 74 and about 1 in 10 people aged 75 or over.
The NHS also notes that some people have symptoms despite apparently normal B12 blood levels, because the vitamin is not reaching the nerves properly. If your symptoms persist, tell your doctor.
How is B12 deficiency diagnosed and treated?
The NHS says B12 deficiency can often be diagnosed from your symptoms and a blood test. For eye symptoms, EyeWiki recommends measuring B12, folate, homocysteine and methylmalonic acid (MMA); raised MMA and homocysteine help confirm deficiency when B12 is low or borderline.
| Step | Who | What happens |
|---|---|---|
| 1. Blood tests | GP or physician | B12, folate and related markers |
| 2. Eye examination | Ophthalmologist | Sharpness, colour vision, visual field, optic nerve appearance, scan of the nerve fibre layer |
| 3. Treatment | GP or physician | B12 replacement by injection or tablets, depending on the cause |
| 4. Follow-up | GP and eye doctor | Repeat blood tests and eye checks to confirm vision is recovering |
Treatment details depend on the cause and on the national guideline. In the UK, the NHS says B12 is usually given by injection at first (every other day at the start). If the cause is not diet-related, injections are usually needed every 2 to 3 months for life, or about every 2 months if there are neurological symptoms. For diet-related deficiency, daily tablets can be an alternative. EyeWiki describes 1,000 µg daily by mouth for one month for reversible causes and lifelong monthly injections for irreversible ones such as pernicious anaemia. Never choose a dose yourself: your doctor sets the regimen after finding the cause.
Other nutritional deficiencies, including folate, thiamine (B1), pyridoxine (B6) and copper, can also damage the optic nerve, which is why doctors may test more than B12 alone.
When should you see a doctor, and when is it urgent?
See a doctor within days if you have:
- blurred or dim vision in both eyes that is not explained by your glasses
- faded colours or a patch of missing vision in the centre
- tingling, numbness, balance problems, tiredness or memory problems together with changed vision
- a vegan diet, long-term metformin or acid-reducing tablets, pernicious anaemia or past stomach surgery, and any new visual symptom
Seek urgent eye care the same day for: sudden loss of vision, a curtain or shadow across your vision, a sudden shower of floaters or flashes, or eye pain with vision loss. These are not typical of B12 deficiency and need a different diagnosis.
At Laser Istanbul Clinic, our surgeons can examine your eyes, assess the optic nerve and macula and tell you whether your symptoms come from the eye itself. Doç. Dr. Muhammet Derda Özer (Doç. means Associate Professor), whose specialties include retina, cornea and uveitis, Prof. Dr. Ahmet Satıcı and Op. Dr. Aysan Bayram can advise on eye symptoms; your B12 level and treatment remain a matter for your own physician. If you already have eye scans or blood results, you can send them for a free review.
Frequently asked questions
Yes, but it is uncommon as a first sign. B12 deficiency can damage the optic nerve, causing painless, symmetrical blurring in both eyes, often with faded colours and a central blind spot. Many other conditions cause blurred vision, so you need an eye examination as well as a blood test.
The main eye symptoms are blurred or dim vision in both eyes, a central blind spot, faded colours and lower contrast. Some studies also link low B12 to dry, painful eyes. The NHS lists problems with vision among the general symptoms, alongside tiredness, pins and needles and a sore tongue.
It may contribute in some people, particularly to nerve-related eye pain, but the evidence is limited and most dry eye has other causes. If you also have tingling, fatigue or other B12 symptoms, ask for a blood test.
No established link was found. Floaters are usually shadows from the gel inside the eye and become more common with age. New or sudden floaters, flashes or a shadow in your vision are urgent and need a retinal check.
Often, if treatment starts early. Sharpness usually improves first, then colour vision. If treatment is delayed by about 3 months or more, or vision is already very poor, recovery is less likely and some damage can be permanent.
The body stores B12 for 2 to 5 years, so deficiency usually develops slowly. Visual symptoms appear when the optic nerve is affected, which is why early testing matters.
Not on your own. Have a blood test first, because the cause of the deficiency decides whether you need tablets or injections. Supplements are not a proven treatment for ordinary dry eyes or blurred vision.
See your GP or physician for the blood test and treatment, and an ophthalmologist for the eye examination. Both matter: one treats the deficiency, the other checks and monitors the optic nerve.
Worried about changes in your vision?
Send us your recent eye scans or blood results and a surgeon from Laser Istanbul Clinic will review them and tell you honestly what to do next.
Sources for the facts on this page
- NHS. Vitamin B12 or folate deficiency anaemia. https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/
- NHS. Vitamin B12 or folate deficiency anaemia: Symptoms. https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/symptoms/
- NHS. Vitamin B12 or folate deficiency anaemia: Causes. https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/causes/
- NHS. Vitamin B12 or folate deficiency anaemia: Treatment. https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/treatment/
- EyeWiki (American Academy of Ophthalmology). Nutritional Optic Neuropathy (section: B12 deficiency optic neuropathy). https://eyewiki.org/Nutritional_Optic_Neuropathy
- American Academy of Ophthalmology. What Are Floaters and Flashes? https://www.aao.org/eye-health/diseases/what-are-floaters-flashes
- Ata F, et al. Optic neuropathy as a presenting feature of vitamin B12 deficiency: a systematic review of the literature. Annals of Medicine and Surgery 2020. PMID 33204422. https://pubmed.ncbi.nlm.nih.gov/33204422/ (conclusion read from a PubMed search listing)
- Ozen S, Ozer MA, Akdemir MO. Vitamin B12 deficiency evaluation and treatment in severe dry eye disease with neuropathic ocular pain. Graefe's Archive for Clinical and Experimental Ophthalmology 2017. PMID 28299439. https://pubmed.ncbi.nlm.nih.gov/28299439/ (conclusion read from a PubMed search listing)
- Furgała R, Stompor M. Effects of vitamin B12 supplementation on pain relief in certain diseases: a literature review. Acta Biochimica Polonica 2022. PMID 35451593. https://pubmed.ncbi.nlm.nih.gov/35451593/
- Fan JZ, Mortensen PW, Raviskanthan S, Lee AG. Combined nutritional keratoconjunctivitis sicca and optic neuropathy due to restrictive dietary multivitamin deficiency. Journal of Neuro-Ophthalmology 2023. PMID 35483069. https://pubmed.ncbi.nlm.nih.gov/35483069/
- Heidari H, et al. The efficacy of oral vitamin supplementation in dry eye disease: a systematic review. Ophthalmic and Physiological Optics 2026. PMID 41984344. https://pubmed.ncbi.nlm.nih.gov/41984344/