Experiencing double vision is often blamed on tiredness or stress – but it could signal that you’re having a stroke, an eye surgeon has warned.
Double vision – medically known as diplopia – is defined by the NHS as seeing two images when looking at a single object, and the health body notes that it can affect one or both eyes.
The condition is recognised as a common warning sign of a brain tumour, but according to Dr Nadeem Ali, Consultant Squint and Double Vision Surgeon at London Squint Clinic, it can also signal a stroke.
He said: ‘When someone develops double vision out of the blue, particularly if they have never experienced it before, that always warrants urgent assessment.
‘If double vision is accompanied by facial drooping, limb weakness, slurred speech, difficulty walking, or severe dizziness, it must be treated as a medical emergency.’
A sudden, severe headache alongside double vision is another red flag.
‘Painful double vision, especially with a new or intense headache, can indicate acute inflammation, infection, or a bleed,’ he said. ‘That is not something to wait out at home.’
There are two types of stroke; firstly is ischemic stroke – which accounts for 80 per cent of strokes. These occur when there is a blockage in a blood vessel that prevents blood from reaching part of the brain.
Double vision – medically known as diplopia – is defined by the NHS as seeing two images when looking at a single object
The second type, a hemorrhagic stroke, is more rare and occurs when a blood vessel bursts, flooding part of the brain with too much blood while depriving other areas of adequate blood supply.
Dr Ali says that double vision can also signal a transient ischaemic attack (TIA), also known as a ‘mini stroke’.
A TIA occurs when there is a temporary disruption of blood flow to the brain, causing sudden, stroke-like symptoms that usually last a few minutes to an hour, but resolve within 24 hours.
TIAs are commonly experienced before a stroke, meaning observation and medical attention is crucial.
According to the RNIB, vision problems are a common complication of stroke. This is because it can affect the nerves and parts of the brain involved in the ‘visual pathway’, which are responsible for processing and interpreting visual information.
The charity claims that the main types of eye problems that can occur after a stroke include visual field loss, eye movement problems and visual processing problems.
People can also struggle with judging depth and movement, recognising objects and people and experience visual hallucinations.
But while double vision doesn’t always signal a stroke, Dr Ali urges people to always take the condition seriously.
He said: ‘The nerves that control eye movement originate in the brain. If one stops working properly, we must establish why.
‘If the symptoms develop gradually, with no other symptoms, double vision may be due to loss of eye control.
‘Double vision, or diplopia, occurs when the eyes are not aligned. This could be a problem with the eye muscles, the nerves controlling them, or the brain.
‘In adults and children, particularly when it appears suddenly, we never just put it down to simple eye strain.
‘People often assume it is screen strain or tiredness, but true double vision is not normal and should not be ignored.’
In cases of glioblastoma – a rare and aggressive form of bran cancer – double vision is a common symptom, typically caused by increased pressure on the brain caused by swelling or the tumour itself pressing on nerves controlling eye movement.
Other causes of double vision include diabetes, multiple sclerosis, thyroid issues or simply eye strain from too much close-up working.
Regardless of the cause, early intervention and assessment allows doctors to rule out serious causes quickly and begin appropriate treatment, which could include prism lenses, medication or surgery.
Dr Ali said: ‘The key message is simple: if you suddenly start seeing double, particularly with other symptoms, seek medical advice immediately. It is always safer to be checked than to miss something serious.’
