Vision problems

Vision problems are changes in what or how you see. Your sight may become blurred, dim, distorted, doubled, or partly blocked. The change may affect one eye or both eyes, and it may start suddenly or develop over time.

Some vision changes come from common focusing problems that glasses or contact lenses can correct. Others happen because the eye surface is dry, a migraine affects visual processing, or an eye condition is developing.

The pattern offers important clues. A gradual change over months is different from sudden loss of vision. New flashes, many new floating shapes, a dark curtain, eye pain, or weakness on one side of the body need prompt medical attention.

Vision problems can affect sharpness, colour, depth, or the amount of your surroundings you can see. They may be constant or come and go.

You might notice:

• Blurred near or distance vision
• Trouble changing focus between near and far objects
• Double vision
• Hazy, cloudy, or dim sight
• Glare, halos, or poor night vision
• Wavy or distorted lines
• Flashing lights, shimmering shapes, or blind spots
• Small spots or strands that drift across your sight
• Loss of side vision or a missing area
• Colours appearing faded or different between the eyes

Covering one eye and then the other can help establish whether a change affects one eye or both. Do not delay urgent care to perform your own tests.

Common causes include refractive errors. These happen when the eye does not focus light clearly. Nearsightedness, farsightedness, and astigmatism can cause blur, squinting, headaches, or eye strain. Presbyopia is the gradual loss of near focus that commonly develops with age.

Dry eye can make vision fluctuate, especially during reading, screen use, driving, or time in dry and windy places. The eyes may also burn, feel gritty, water, or become red.

Cataracts are cloudy areas in the eye’s natural lens. They usually cause gradual blurring, glare, faded colours, or difficulty seeing at night.

Migraine aura can cause zigzags, flashing lights, shimmering areas, or a temporary blind spot. It often affects the visual field of both eyes, even if it seems stronger on one side. It can happen before a headache or without one.

Less common causes include problems affecting the cornea, retina, optic nerve, or the parts of the brain involved in vision. Examples include glaucoma, macular degeneration, inflammation, infection, and conditions affecting eye movement. Changes in blood sugar and some medicines can also alter vision.

Urgent causes include retinal detachment, blocked blood flow to the eye, sudden pressure rise inside the eye, serious infection, injury, and stroke. These cannot be identified safely from symptoms alone.

Call emergency services for sudden major or complete vision loss, especially if it occurs with facial drooping, arm or leg weakness, trouble speaking, severe dizziness, or a sudden severe headache. These can be signs of a stroke or another emergency.

Emergency assessment is also appropriate after a serious eye injury. If a chemical enters the eye, begin rinsing it with plenty of clean, lukewarm water immediately and seek emergency advice.

Arrange urgent, same-day assessment for:

• A dark curtain or shadow moving across your sight
• New flashes with many new floaters
• A painful red eye with blurred vision, halos, nausea, or vomiting
• Sudden double vision
• Sudden loss of part of the visual field
• Pain, redness, and blurred vision while wearing contact lenses
• A sudden change after eye surgery or an eye procedure

Book a routine eye examination if blurred vision persists, keeps returning, or affects reading, work, driving, or other activities. Gradual changes, frequent headaches with visual tasks, worsening night vision, or an outdated glasses prescription also deserve assessment.

People with diabetes or an existing eye condition should follow their planned eye-review schedule and report new changes rather than waiting for the next routine visit.

An eye care professional will ask when the problem began, whether it affects one or both eyes, and whether it is constant or intermittent. Mention pain, redness, headaches, flashes, floaters, injury, medicines, contact lens use, and any weakness or speech difficulty.

Your vision may be checked at different distances and with different lenses. The examination may assess your pupils, eye movements, side vision, colour vision, and how the eyes work together.

A microscope called a slit lamp allows close examination of the front of the eye. Eye pressure may be measured. Dilating drops may be used to widen the pupils so the retina and optic nerve can be examined. These drops can temporarily blur near vision and increase sensitivity to light.

Depending on the findings, you may need retinal imaging, a visual-field test, blood tests, or brain imaging. Not everyone needs these tests.

Treatment depends on the cause. Focusing problems may improve with glasses, contact lenses, or another form of vision correction. Dry eye care may include lubricating eye drops, treating eyelid irritation, and adjusting activities or surroundings that worsen symptoms.

Cataracts, glaucoma, retinal conditions, infection, inflammation, and nerve problems each need specific treatment. Migraine-related symptoms may improve with a migraine management plan after other important causes have been considered.

Until you know what is affecting your sight:

• Avoid driving or using machinery if you cannot see safely
• Take breaks from prolonged close work and remember to blink
• Remove contact lenses if the eye becomes painful, red, or unusually blurred
• Use good lighting for reading and detailed tasks
• Do not use leftover prescription eye drops

Steroid eye drops should only be used under professional supervision because they can worsen some infections and raise eye pressure. Eye vitamins do not treat every type of vision problem and should not replace an examination.

The outlook depends on the cause and how quickly it is treated. A focusing error may improve as soon as the correct lenses are used. Dry-eye blur may fluctuate, while cataract-related changes usually develop gradually.

Migraine-related visual symptoms are often temporary. However, a first episode, an unusual pattern, or symptoms affecting only one eye should be assessed because other conditions can look similar.

Some retinal, pressure-related, blood-flow, and neurological problems are time-sensitive. Prompt care gives the best chance of protecting vision. Long-term conditions may need regular examinations even when you do not notice further change.

Are new floaters always an emergency?

A few stable floaters that have been present for a long time are often not urgent. New floaters, a sudden increase, flashes, or a curtain-like shadow need same-day assessment because they can occur with a retinal tear or detachment.

Can screens permanently damage my eyes?

Screen use commonly contributes to temporary dryness, strain, headaches, and blurred focus. These symptoms often improve with breaks and changes to your setup. Persistent or one-sided changes still need an eye examination.

Can migraine cause vision changes without a headache?

Yes. A migraine aura can occur without headache. Because flashing lights and blind areas can have other causes, seek medical advice for a first episode or a pattern that is sudden, unusual, or limited to one eye.

Should I wait for my routine eye test?

Not if the change is sudden, painful, or accompanied by flashes, many new floaters, a curtain-like shadow, or neurological symptoms. Gradual, stable changes can usually be discussed at a routine appointment.