On a January morning in 2018, Sasha Clark was preparing for work when her vision suddenly became blurred.
Believing a migraine was coming on, she took two ibuprofen and waited for the problem to clear.
Closing one eye gave her some clarity, but with both eyes open, everything appeared indistinct.
“Whether I was watching television or looking at my phone, I had to keep one eye closed to see properly,” says Sasha, now 28, a charity worker from Essex.
Within a fortnight, however, her condition had deteriorated sharply. “My coordination was completely wrong and I struggled to eat. I would pick up food with a fork and move it towards my mouth, only to realise my mouth wasn’t where I thought it was.”
Her balance soon suffered too, and she could no longer walk without using the walls for support.
“I had constant headaches and kept taking painkillers, expecting them to work, but nothing helped,” she says. “I was sleeping for 18 hours a day and still felt exhausted. I couldn’t leave the house, use the toilet independently or bathe myself.
Two months after waking up unable to see clearly, Sasha Clark was diagnosed with multiple sclerosis, an incurable autoimmune disease
“I was 19 and should have been enjoying university life—not confined to bed while my mum washed my hair and dressed me.
“That was when I realised something much more serious had to be happening, because my health had declined so rapidly.”
By March, just two months after her symptoms began, Sasha had been diagnosed with multiple sclerosis (MS), an incurable autoimmune disease.
The condition attacks myelin, the protective layer around nerves, particularly those in the brain and spinal cord. It can also damage the optic nerves, interrupting communication between the eyes and brain and causing serious vision problems.
A 2025 study from researchers in Canada found that neurology and ophthalmology visits begin to increase eight to nine years before an MS diagnosis.
‘There is a lot more awareness of the early symptoms of MS now,’ says Dr Aravinthan Varatharaj, clinical academic neurologist and associate professor at the University of Southampton.
‘But while many people are familiar with MS symptoms caused by damage to the brain and spinal cord, such as walking problems, balance issues and bladder or bowel difficulties, far fewer know how MS can affect the optic nerves and vision.
‘The optic nerves are heavily coated in myelin, making them particularly vulnerable to damage from MS.’
Damage to the optic nerves causes optic neuritis. Symptoms typically develop over several days and can include eye pain, blurred vision, blind spots, washed-out colours and flashing lights.
Neurologist Dr Aravinthan Varatharaj says that while many people are familiar with MS symptoms such as walking problems, balance issues and bladder or bowel difficulties, far fewer know how MS can affect the optic nerves and vision
While optic neuritis often improves on its own over a few weeks, it is important to visit an optician who can check for damage to the nerve fibres at the back of the eye.
Besides MS, inflammation of the optic nerve can occur with other conditions, including infections or immune diseases such as lupus.
‘It is really important to recognise that sometimes, even though it gets better on its own, optic neuritis can be the first episode of what may later turn out to be MS,’ says Dr Varatharaj.
Dr Catherine Godbold, senior research communications manager at the MS Society UK, says: ‘The latest research shows that if we can understand this period before a diagnosis or clinical onset of typical symptoms, we could combine it with other data and identify people at higher risk of developing MS. We’re currently funding a new study at King’s College London that aims to do just that.’
While optic neuritis is the most common eye problem linked to MS, it isn’t the only one.
The condition can also disrupt nerve pathways that control eye movements, causing double vision, difficulty reading, distorted straight lines or overlapping images.
Because the parts of the brain that control eye movements sit close to areas involved in balance, co-ordination and nausea, double vision caused by MS is often accompanied by other symptoms, such as being unsteady on your feet or feeling sick.
Another, less common, symptom is oscillopsia, which can make surroundings appear to bounce while walking because the brain can no longer stabilise visual information.
As with other MS-related visual symptoms, these problems usually evolve over days, last for a while and then begin to improve, especially when MS is treated promptly.
Sasha’s advice for others is to trust their instincts and push for answers. ‘Be quite firm with your GP – if you feel like something’s not right, listen to your body and keep investigating,’ she says.
‘MS doesn’t always start with obvious mobility problems. For some people, vision changes or problems with fine motor skills can be among the first signs.’
