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Facts about impaired vision and acute warning symptoms

Visual impairment

Vision loss can develop slowly or occur suddenly and can be caused by changes in the eye, optic nerve or visual pathways in the brain. Sudden loss of vision, loss of visual fields or a red and painful eye with reduced vision should be evaluated urgently.

Facts and guidance

How quickly the vision changes determines how urgent the assessment is

Slow vision loss is often due to refractive errors, cataracts, or other eye diseases. A sudden change, however, can be due to problems with the retina, blood circulation, optic nerve, or stroke.

It is important to distinguish whether one or both eyes are affected, whether the field of vision is partially lost, and whether the symptoms are combined with pain, headache, or neurological deficits.

Read moreTo facts and advice

Important parts of the assessment

One or both eyes
Sudden or slow onset
Field of view
Eye pain
Flashes of light
Neurological symptoms
Eye examination
Targeted MRI
How the investigation can be structured

From initial assessment to the right next step

First determine if the change came on suddenly and if the eye hurts. Then, visual acuity, visual field, fundus and, if necessary, the nervous system are examined.

1

Assess how vision changed

Timing, one or two eyes, visual field, and associated symptoms determine how quickly care is needed.

2

Examine the eye

Visual acuity, pupils, eye pressure, anterior eye, and retina often need to be assessed.

3

Investigate the nervous system if necessary

Neurological examination and MRI are used when the optic nerve, visual pathways or brain are suspected.

That's how it all fits together.

Vision depends on an unbroken signal pathway from the eye to the brain.

The lens and retina create and register the image, the optic nerve transmits the signals and the brain's visual center interprets them.

What is meant by visual impairment?

Visual impairment means that visual function is worse than before or cannot be fully corrected with regular glasses. This may apply to visual acuity, contrast, color vision, night vision or parts of the visual field.

Blurred vision is not always the same as vision loss. Dry eyes and refractive errors can cause temporary blurring, while damage to the retina, optic nerve, or visual pathways can cause more permanent problems.

Also read about visual disturbances when vision changes temporarily, flickers or is affected in connection with a headache.

Common and possible causes of vision loss

Refractive errors, cataracts, glaucoma and changes in the macula are common causes of slowly deteriorating vision. Diabetes can affect the blood vessels in the retina and requires regular check-ups.

Retinal detachment can cause flashes of light, new clouding, and a dark curtain or shadow in the field of vision. Acute glaucoma can cause a red, painful eye, headache, nausea, and rapid vision loss.

Stroke and other changes in the brain's visual pathways can cause visual field loss. Inflammation of the optic nerve can cause impaired vision and pain when moving the eyes.

When should you seek medical attention quickly?

Seek emergency care in the event of sudden vision loss, new loss of visual field, or rapid deterioration. The same applies to a red and painful eye with visual impairment.

Flashes of light, many new black dots, or a dark shadow in the field of vision should be assessed urgently as the retina may be affected.

Call 112 if the vision change is combined with a drooping corner of the mouth, weakness, loss of sensation, speech problems, severe dizziness or other suspicion of stroke.

Sudden vision loss is acute

Do not wait for a scheduled private examination in case of sudden vision loss or other possible stroke symptoms.

How is impaired vision investigated?

The assessment begins with when the change began, whether one or both eyes are affected, and whether there is pain, flashes, clouding, or neurological symptoms.

Eye examination may include visual acuity, pupillary response, intraocular pressure, visual field, microscopy, and examination of the retina. Optical coherence tomography can image the retina and optic nerve.

Blood pressure, blood sugar and other tests may be relevant when vascular disease, diabetes, inflammation or other systemic disease is suspected.

When is brain MRI used for visual impairment?

Brain MRI may be relevant when the eye examination or other symptoms suggest an impact on the optic nerve, visual pathways, pituitary gland or brain.

MRI is not the first examination for many diseases of the cornea, lens, retina or eye pressure. These are best assessed through a targeted eye examination.

In the case of acute neurological symptoms, emergency medical diagnostics and sometimes CT are used before MRI. It is therefore important to seek immediate medical attention rather than choosing a planned examination yourself.

What can you document for an assessment?

Do not test your vision repeatedly over a long period of time when the change is sudden. Instead, note the time of onset, which eye is affected, and whether any part of your visual field is missing.

Bring a current medication list and information about diabetes, high blood pressure, migraines and previous eye diseases.

Avoid driving if your vision is suddenly affected. Ask someone to help you seek medical attention or call 112 if you have stroke symptoms.

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FAQ

Frequently asked questions about vision impairment

When is vision loss acute?

When vision suddenly deteriorates, when part of the field of vision disappears or when a red, painful eye experiences poor vision.

Can stroke only affect vision?

Yes. Stroke can sometimes cause visual field loss or other visual impairment, but there are often other neurological symptoms as well.

Can retinal detachment hurt?

No, it is often painless but can cause flashes of light, clouding and a dark shadow in the field of vision.

Is MRI needed for blurred vision?

Not always. Eye examination is often more relevant. MRI is used when optic nerve, visual pathways or brain are suspected.

What does a visual field test show?

It maps which parts of the visual field you can perceive and can provide clues about where the signal pathway is affected.

Should I book a private MRI in case of sudden vision loss?

No. Sudden vision loss should be assessed urgently by healthcare professionals.