Blurry Vision

Why is my vision blurry?

Whether your vision is blurred in one or both eyes, temporarily, suddenly or gradually, we understand that anything that impairs your vision can be concerning.

What’s the difference between blurry and cloudy vision?

Unlike blurry vision, where objects are out of focus or distorted, cloudy vision is like looking through a foggy window. It can make colours seem muted and give you halos around lights. Cloudy vision may be accompanied by blurred vision and is often the result of cataracts.

Blurry vision and headaches

The most common cause for both a headache and blurred vision is usually uncorrected vision problems such as needing new or updated glasses or contact lenses.

Even if you generally have ‘perfect vision’, some blur and eye strain are normal when our eyes are tired or overworked. This strain can often feel like discomfort in the frontal brow or a headache. Often referred to as asthenopia, this eye strain can have several underlying causes, including general over concentration, loss of focus in the eye due to presbyopia, or other issues such as eye muscle problems.

Another cause could be a migraine. People who suffer from migraines report temporary vision loss or blurred vision as a result of distorted lines or colours, sometimes in one eye and sometimes in both. Ocular migraines don’t always have accompanying headache pain like a regular migraine.

Other causes for blurred vision and headaches could include:

• Low blood sugar: If your blood sugar gets too low, you can become hypoglycaemic, which means your brain is in desperate need of glucose to keep it going.

• Stroke: Aside from other symptoms like facial and arm weakness and slurred speech, a stroke can cause a headache and blurred vision. If you suspect a stroke act quickly and seek medical help.

• Head trauma: A bump to the head can lead to a concussion, with symptoms of headaches and blurry vision, appearing in the hours, days, or even weeks afterwards.

• Carbon monoxide poisoning: When you burn fuel, you produce carbon monoxide, which is odorless and dangerous if inhaled. A common sign that you have carbon monoxide poisoning is a headache with blurry vision.

Blurry vision during pregnancy

Aside from sickness, achy back and all the other side effects of growing another human being, the fluctuations in hormone levels during pregnancy can also slightly impair your vision.

If you have blurry vision during pregnancy, you might experience:

• Dry or irritated eyes: Hormonal changes can reduce tear production, making your eyes feel uncomfortable.

• Blurred or distorted vision: Temporary shifts in vision can occur due to fluid retention in the cornea.

• Eye floaters: Small specks or shadows might appear in your field of vision.

• Contact lens discomfort: Lenses might feel tighter or irritate you due to the moisture changes in your eyes. 

For those at risk of preeclampsia or gestational diabetes, it’s best to talk to your midwife if you notice any changes to your vision. Most women find their vision returns to normal soon after giving birth, but it's always important to visit your optician or GP just in case these problems are a symptom of something other than hormonal changes.

It’s also worth noting that if you aren’t experiencing any eye symptoms during pregnancy, you can continue to wear your lenses as normal.

Blurry vision and diabetes

If you’re diabetic, you’ll need to be monitored closely for diabetic retinopathy, a complication of diabetes that damages the light‑sensitive layer at the back of the eye called the retina.

Possible symptoms to watch out for include:

• Blurred or fluctuating vision: Changes in blood sugar can cause vision to become blurry or shift throughout the day.

• Dark or empty areas in your vision: Damage to the retina can create blind spots or shadows in your field of vision.

• Difficulty seeing at night: Reduced retinal function can make it harder to see at night.

• Floaters or spots: Specks or shapes that drift through your vision can be a sign of diabetic retinopathy.

Early stages may not affect vision, which is why regular eye checks are essential. Monitoring blood sugar and attending routine eye exams can help catch changes before they become serious.

Blurry vision in the morning

For most people, blurry vision in the morning is caused by a lack of tears on the front of your eye. This usually clears up after you blink a few times as the natural debris is removed and the tear film refreshes.

Common causes of blurry vision in the morning include:

• Dehydration: Lack of fluids can reduce tear production, resulting in dry eyes and blurred vision.

• Allergies: If you have any allergies, they can inflame the eyes and temporarily affect clarity.

• Sleeping with the fan on: Air movement can dry out your eyes overnight.

• Overnight contact lens use: Wearing lenses overnight when they’re not designed for it can trap debris and reduce oxygen to your eyes.

• Certain medications: Some medications can affect your vision. 

If your morning blurry vision persists or feels like it's getting worse, consult an eye care professional to rule out more serious issues.

What causes sudden blurred vision in one eye?

If you begin to experience sudden blurry vision in one eye, the first thing to check is if there is something in it. If there is, try blinking slowly to push it to the corner of your eye and to create tears. However, if chemicals have splashed into your eye, or you feel something has penetrated your eye, seek immediate medical attention.

Other conditions of blurred vision in one eye to look out for are:

• Conjunctivitis: Also known as pink/red eye

• Corneal infections: This includes ulcers, keratoconus, ocular herpes or a damaged/scratched cornea

• Uveitis: A catch‑all term for inflammation of the inside of the eye

• Optic neuritis: An inflammation of the optic nerve

• Acute glaucoma: A fast rise in eye pressure that will be accompanied by pain and blurred vision.

• Retinal detachment: A serious but rare condition where the retina separates from its blood supply.

• Retinal vein occlusion: Caused by a blockage in the blood vessels at the back of the eye.

Blurred vision in both eyes

While sudden blurred vision in one eye is generally considered more dangerous for vision itself, if you experience sudden blurred vision in both eyes, this suggests a more systemic issue. This includes diabetes, high blood pressure and even medication side effects. Blurred vision in both eyes isn’t necessarily sight‑threatening, but it can still indicate an underlying health problem.