Blurred vision: common causes and when to see a specialist

Blurred vision is the single most common eye complaint I see. Most causes are simple and treatable, but a small number are sight-threatening and need same-day review. This guide walks through the pattern of blur, the likely causes, and what to do next.

Sudden vs gradual

The single most useful question is: did the blur come on **suddenly** (minutes to hours), **quickly** (a few days), or **slowly** (weeks to years)?

Sudden blur in one eye is potentially serious: retinal detachment, vitreous haemorrhage, retinal vein or artery occlusion, wet age-related macular degeneration, optic neuritis or a stroke can all present this way. Attend eye casualty the same day.

Gradual blur in both eyes is almost always a benign, treatable cause: refractive error, cataract, dry eye or presbyopia.

The commonest gradual causes

**Uncorrected refractive error.** By far the commonest cause in UK adults. A change in glasses prescription every 1–2 years is normal from the mid-40s. If your last sight test was more than two years ago, start there.

**Presbyopia.** From around 45 the natural lens loses focusing flexibility, so reading print and phone screens becomes an effort. Correction options range from reading glasses to varifocals to lens replacement surgery.

**Cataract.** Gradual haze, faded colours, glare at night, difficulty reading road signs. Now treatable by day-case cataract surgery with excellent outcomes.

**Dry eye.** Blur that clears with a blink or fluctuates through the day. See our dry eye guide.

**Diabetic eye disease.** Any diabetic with new blur must have a dilated retinal check within days. Blood-sugar swings alone can also cause temporary blur.

**Age-related macular degeneration.** Distortion of straight lines (door frames, window frames) and a central blurred or missing spot. Wet AMD needs urgent intravitreal treatment.

The commonest sudden causes

**Retinal detachment.** Blur preceded by floaters, flashes and a curtain across vision — same-day emergency. Detail in floaters and flashes.

**Vitreous haemorrhage.** Blur, dark cloud or shower of red spots, often in diabetics or after trauma.

**Retinal vein occlusion.** Painless blur in one eye, often on waking, in patients with high blood pressure.

**Optic neuritis.** Blur with pain on eye movement, often in adults under 40 — needs neurology assessment for possible multiple sclerosis.

**Stroke.** Sudden loss of vision on one side, especially with weakness or slurred speech — call 999.

Red flags — same day review

Contact eye casualty or call 111 the same day if blur comes with:

- Sudden onset in one eye

- Flashes, floaters or a shadow across vision

- Eye pain, redness or headache

- Weakness, numbness or slurred speech

- Recent eye surgery or trauma

- Contact lens in a red eye

How the cause is worked out

In a private consultation I would:

- Measure best-corrected acuity

- Perform full refraction

- Examine the anterior segment with a slit lamp

- Perform OCT of the macula and optic nerve

- Dilate to examine the retina

One visit is usually enough to identify the cause and put a plan in place.

Next steps

If your blurred vision has been building for weeks or months, an up-to-date optometry test is the right first step. If it started suddenly, or if an optometrist has spotted a change on OCT, you can book a private consultation or call **020 3137 3237** for a specialist assessment.