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Many stroke survivors have undiagnosed vision problems. A new study found that more than half of those with a new visual impairment do not – or cannot – report symptoms. The researchers say that all stroke survivors should have thorough assessments of their vision. Relying on reported symptoms alone is not enough.

More than 1.3 million people in the UK have survived a stroke. Two in three are left with problems with their vision. Specialist support services can help stroke survivors make the most of their remaining vision and maintain their independence. But some stroke survivors do not report any visual symptoms, even when they are later found to have problems. This could mean their visual impairments are overlooked. 

The Impact of Visual Impairment after Stroke (IVIS) project was set up to evaluate long-term outcomes for people with visual problems. This study is part of IVIS and looked at how common it is for stroke survivors to have visual impairments without reporting symptoms. 

The findings may help develop more effective screening and assessment methods for stroke-related visual problems. This work has informed changes to NICE guidance [CG162], the National Clinical Guidelines for Stroke, and the British and Irish Orthoptic Society extended practice guidelines. Stroke survivors and their families may wish to ask for full vision screening to ensure any problems are spotted early and treatment is offered where possible. 

What’s the issue?

More than 100,000 people have a stroke each year in the UK. Stroke is a life-threatening condition that occurs when the blood supply to part of the brain is cut off. Survival rates are improving and greater focus now lies in supporting people after a stroke.

If a stroke affects parts of the brain that control and receive information from the eyes, this can cause vision problems. There are a variety of stroke-related visual impairments, and patients may report a wide range of possible visual symptoms. These include the loss of areas of vision (visual field loss), blurred and double vision, reading difficulties, and visual hallucinations (seeing something that is not there). 

Many stroke survivors do not report visual symptoms even when clinical examination reveals an impairment. A missed diagnosis can have a considerable impact on the person’s general rehabilitation and their ability to do everyday activities. Untreated vision problems impact the person’s quality of life.

The IVIS study looked at reported symptoms among participants to find out what proportion of stroke survivors do not, or cannot, report vision problems.

What’s new?

The IVIS study was carried out at three hospitals in the north-west of England. It included 1,500 people who had been admitted for a stroke. 

1,204 participants had their vision fully assessed by an orthoptist (a specialist in diagnosing and treating defects in eye movement and problems with how the eyes work together). The researchers reviewed the participants’ hospital notes for previous eye problems and took medical histories from the participant and/or their carer. 

703 participants had a new or partially new visual impairment. 

    • Almost half (47%) reported visual symptoms. Most reported symptoms in the days following their stroke, but some only reported symptoms later, after their discharge from hospital. 
    • More than one in three (38%) did not report any visual symptoms.
    • A further 15% were unable to report symptoms during their follow-up. This group were older and had experienced a more severe stroke compared with those who did report symptoms.

Stroke survivors with a manifest squint (which can be seen while the eyes are open) and a loss of function in the ocular cranial nerves (running from the brain to the eye muscles) were more likely to report symptoms.

The more severe the visual impairment, the less likely the person was to report symptoms. 

Why is this important?

These findings raise awareness of the high number of unreported visual symptoms among stroke survivors. It provides evidence to support full vision screening for all stroke survivors. This screening should include objective assessments and not rely on the patient being able to report their symptoms. 

The study identifies several reasons why stroke survivors may not report any symptoms, even when they have a severe impairment. In some cases, they may not notice the problem or there may not be any obvious symptoms. Other stroke survivors may feel that their symptoms are not serious enough to report.

Some may be aware of their symptoms but reluctant to mention them because they want to be allowed to continue activities such as driving. People experiencing visual hallucinations, which are a normal response of the brain to loss of vision, may worry about their mental health. 

What’s next?

Current stroke screening typically assesses visual field loss with tools such as the National Institutes of Health Stroke Scale (NIHSS). However, some assessments are not routine on stroke units. For example, assessing visual acuity (clarity of vision) or eye alignment (whether the two eyes look in the same direction).

Specialist screening tools include the assessment of visual acuity, eye alignment, and reading. Such screening is important because visual impairments can make it difficult for stroke survivors to stay mobile, manage daily activities, and retain their independence. Without suitable treatment, vision problems may damage their wellbeing and quality of life.

Further research is needed to explore whether implementing comprehensive vision screening for all stroke survivors can prevent missed diagnosis of vision problems and lead to better outcomes for stroke survivors.

You may be interested to read

This NIHR Alert is based on: Hepworth LR, and others. “Eye” Don’t See: An Analysis of Visual Symptom Reporting by Stroke Survivors from a Large Epidemiology Study. Journal of Stroke and Cerebrovascular Diseases 2021;30:6 

Another paper from the same research team: Rowe FJ, and others. Impact of visual impairment following stroke (IVIS study): a prospective clinical profile of central and peripheral visual deficits, eye movement abnormalities and visual perceptual deficits. Disability and Rehabilitation 2020;21:1–15

National Institute for Health and Care Excellence (NICE) guidance [CG162]: Stroke rehabilitation in adults 2013.

National Clinical Guidelines for Stroke. Royal College of Physicians. 2016, 5th edition. 

Information for patients on stroke-related eye conditions from the Royal National Institute of Blind People (RNIB).

Resources developed by the VISION Research Unit for patients, families and carers.  

 

Funding: This study was funded by an NIHR Career Development Fellowship award. 

Conflicts of Interest: The study authors declare no conflicts of interest.

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.


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