nutritional optic neuropathy

Primer on Nutritional Optic Neuropathy

A young boy, aged 17, made the news when he developed a form of blindness after years of malnourished dieting.

After examination, it was found that the teenager’s diet had given him nutritional optic neuropathy, a type of acquired optic neuropathy.

Optic neuropathy is when the optic nerve is damaged which can then lead to changes in the individual’s sight. This is due to damage done to the retinal ganglion cells and their axons which can cause modifications to the optic nerve head as well as the surrounding retinal nerve fibre layer.

Optic neuropathy can be caused by a variety of factors, including trauma, drugs, and genetics. Nutritional optic neuropathy occurs when the body is deficient in certain nutrients due to the individual’s diet.

Although those who develop this type of optic neuropathy solely due to nutritional malpractice are rare (they are more commonly found in regions where famine is prevalent), lacking certain nutrients is often a big factor in the progression of other forms of this condition.

Some of the main deficiencies responsible for nutritional optic neuropathy include:

  • Vitamin B-12 (cyanocobalamin)
  • Vitamin B-1 (thiamine)
  • Vitamins B-2 (riboflavin)
  • Folate

In the case of the teenager mentioned above, his diet consisted of chips, crisps, white bread, and sausages, which left his body in need of more vitamin B-12, among other nutrients.

In the early stages of nutritional optic neuropathy, visual acuity is normally the first to worsen. At this stage, if treated correctly, it is possible to reverse the detriment done and recover lost sight. If left untreated, patients can lose central vision as well as the ability to distinguish colours.

Damage can be permanent so it is important to seek clinical advice as soon as any change in sight is noticed so that treatment can start. An improvement in diet as well as vitamin supplements can help with staving off the later stages of the condition.

It must be noted that due to the rarity of primarily nutritional optic neuropathy in developed countries, the selectiveness of the diet could be a symptom of avoidant restrictive food intake disorder (ARFID), an eating disorder that is not due to body image issues.

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Luxturna gene therapy for sight loss on the NHS

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This week, the BBC reported that gene therapy may become available on the NHS for those with visual impairments. With a commercial price of £613,410 per person, the NHS have managed to come to an agreement with global drug company Novartis over treatment with voretigene neparvovec (commercially known as Luxturna) and it is expected that treatment will be available from January 2020.

Let’s go through the main points:

  • Eligibility for the treatment is very specific – Voretigene neparvovec is targeted at those with inherited retinal dystrophies due to a mutation in the RPE65 gene, which aids the production of proteins vital to normal vision. The National Institute for Health and Care Excellence (NICE) estimate that approximately 86 people in England will be eligible.
  • Voretigene neparvovec aims to stabilise vision and prevent further sight loss – Unfortunately the treatment does not aim to restore vision that has already been lost.
  • Location may be important – NICE lists NHS England as the only NHS consultee for the proposed treatment. Furthermore, in reports, quotes from the NHS have come from Simon Stevens, the CEO of NHS England. This could suggest that the treatment will only be available to those living in England and Wales (who are legally obliged to fund NICE guidance). Those with the condition in Scotland and Northern Ireland will have to wait on separate decisions to be made. Additionally, according to a statement by NHS England, the treatment will initially be rolled out in three national specialist centres across the UK. Making it available to other hospitals later is an option and not mandatory.
  • Injections in the eye – The treatment is administered by a one-time injection under the retina of each eye. Normally, one eye will be treated first, with the other treated after at least 6 days. The injections aim to introduce a healthy version of the RPE65 gene which can then help production of the protein needed for normal vision.
  • Long-term effects are unclear – Studies have shown shorter term benefits (3 to 4 years) but longer term effects are uncertain. However, clinical experts feel that there is a “biological rationale” for the effects of the treatment to remain.
  • There are side effects – As with most treatments, there are potential side effects and these can be found on Luxturna’s website. Some of the more serious ones include eye infections, permanent decline in visual acuity or sharpness of central vision, as well as further sight loss due to various potential changes to the eye.
  • Not set in stone – This treatment is still currently in progress with final evaluation determination expected to conclude by 20th September 2019. It is still a possibility (admittedly a minute one) that the availability of Luxturna could be delayed. However, the NICE guidance is expected to be published on the 9th October 2019, which then gives NHS England three months to make it available “as an option”.

Please see the NICE website for full details and status of the treatment.