15 Main Causes of Blurred Vision

2. Conjunctivitis

Conjunctivitis, often called pink eye, occurs when the thin, clear layer that covers the white part of your eye and lines the inside of your eyelids becomes inflamed. When this membrane swells, the eye may appear red or pink and feel irritated. Inflammation can increase tear production and mucus discharge.

This fluid may collect on the surface of the eye and temporarily blur vision. Thick discharge can also cause the eyelids to stick together, especially after sleep. Conjunctivitis may develop from viral or bacterial infections, allergies, or irritation. Viral and bacterial forms can spread through hand-to-eye contact or shared personal items.

Allergic conjunctivitis does not spread between people. Wearing contact lenses can increase the risk of infection, especially if they are not cleaned properly. Common symptoms include redness, watery or thick discharge, itching, and a gritty sensation in the eye.

3. Sleeping with Contacts

Sleeping with contact lenses can increase the risk of blurred vision. Contact lenses sit directly on the cornea, the clear front surface of the eye. When your eyes close during sleep, less oxygen reaches the cornea. Because contact lenses already limit some oxygen flow, wearing them overnight can reduce oxygen levels even further.

Low oxygen can cause the cornea to swell. This swelling may make vision appear cloudy or hazy when you wake up. Your eyes may also feel dry, irritated, or sensitive to light. Keeping lenses overnight can also increase the risk of infection. Germs can attach to the lens surface and remain trapped against the eye for many hours.

Infections such as keratitis may lead to pain, redness, discharge, and persistent blurry vision. The risk becomes higher if you sleep in lenses that are not approved for overnight wear. Even lenses labeled for extended wear can cause problems if they are not cleaned and replaced as directed.

4. Cataracts

Cataracts develop when the clear lens inside your eye becomes cloudy. This happens as proteins in the lens gradually break down and clump together, which makes the lens less transparent. Cataracts usually develop slowly over time, and aging is the most common cause. Certain health conditions and lifestyle factors can also increase risk.

People with diabetes, those who smoke, drink large amounts of alcohol, or spend long periods in the sun without eye protection may face a higher chance of developing cataracts. Past eye injuries, eye surgery, or long-term use of corticosteroid medicines can also contribute. As the cloudy lens blocks and scatters light, less clear light reaches the retina at the back of the eye. This makes vision appear dim, hazy, or out of focus.

As cataracts worsen, vision may change in several ways. Colors may look faded or yellow, bright lights may seem too strong, and glare or halos may appear around lights at night. Some people may also notice double vision in one eye or need new glasses more often.

5. Glaucoma

Glaucoma is a group of eye diseases that damage the optic nerve, which carries visual signals from your eye to your brain. Damage to this nerve can gradually affect vision and may lead to permanent vision loss. In many cases, glaucoma develops when pressure inside the eye slowly rises.

This pressure can injure the optic nerve over time. The most common form, called open-angle glaucoma, usually progresses slowly and may not cause noticeable symptoms in the early stages. In some cases, optic nerve damage can develop even when eye pressure remains within normal ranges and certain factors can increase the risk of glaucoma.

People over age 60, those with a family history of the condition, and individuals with health problems such as diabetes or high blood pressure may face a higher risk. As optic nerve damage develops, vision changes may begin to appear. Blurred vision often starts with loss of side vision, which can make it feel as though you are looking through a tunnel.

6. Macular Degeneration

Macular degeneration is an eye condition that affects the macula, the small central part of the retina responsible for sharp, detailed vision. This area helps you read, drive, and see fine details clearly. The condition usually develops after age 50. Over time, damage occurs in the light-sensitive cells of the macula, which reduces the eye’s ability to process detailed visual information.

There are two main types of macular degeneration. The dry form develops when cells in the macula slowly wear down over time. The wet form occurs when abnormal blood vessels grow beneath the macula and leak fluid or blood, which can cause faster vision changes.

As macular damage progresses, central vision may become blurry or distorted. Straight lines may appear wavy or crooked, and a dark or empty spot may form in the center of your sight. Side vision usually remains normal, but tasks that require fine detail become harder.

7. Diabetes

Diabetes can cause blurred vision when blood sugar levels remain high for long periods. Elevated glucose levels can temporarily change the shape of the lens inside your eye. This may cause vision to shift between clear and blurry. Over time, continued high blood sugar can damage the small blood vessels in the retina, the light-sensitive layer at the back of the eye.

This condition is known as diabetic retinopathy. The vessels may swell, leak fluid, or bleed, interfering with how the retina processes light. In the early stages, diabetic eye damage may not cause noticeable symptoms. As the condition progresses, people may begin to see floaters, dark spots, wavy lines, or blank areas in their vision. Long-term diabetes can also increase the risk of other eye conditions.

These include cataracts, where the lens becomes cloudy, and glaucoma, which damages the optic nerve due to increased pressure inside the eye. The risk of eye damage increases the longer a person has diabetes, especially when blood sugar or blood pressure remains poorly controlled.

8. High Blood Pressure

High blood pressure can blur your vision by damaging the tiny blood vessels in the retina, the light-sensitive layer at the back of your eye. When blood pressure remains high over time, these vessels may become narrow, leak fluid, or become blocked. These changes reduce normal blood flow and interfere with how the retina processes light. When the retina cannot function properly, vision may become less clear.

In the early stages, many people do not notice symptoms. As the damage progresses, vision changes may appear, including dim vision, double vision, or sudden vision loss. This swelling can further reduce vision and may occur along with headaches. Certain factors increase the risk of eye damage from high blood pressure. People with diabetes, high cholesterol, or those who smoke may face a higher chance of vision problems.

9. Hyperopia

Hyperopia, also called farsightedness, is a common cause of blurred vision. In this condition, distant objects often appear clearer than close ones. Hyperopia occurs when the eye does not bend light properly. Instead of focusing directly on the retina, the light-sensitive layer at the back of the eye, light focuses behind it. Because the image does not land in the correct place, nearby objects may appear blurry. The eye may try to adjust its focus to compensate for this problem.

Children and younger adults can sometimes do this for a time, which may hide the condition in the early stages. Over time, this constant effort can lead to symptoms such as eye strain, headaches, or a burning or aching feeling around the eyes. Activities such as reading, using a phone, or working on a computer may become difficult.

10. Astigmatism

Astigmatism is a common cause of blurred vision. It occurs when the cornea, the clear front surface of the eye, has an uneven curve instead of a smooth round shape. Rather than being curved like a basketball, the cornea may be shaped more like a football.

Because of this uneven surface, light entering the eye cannot focus evenly on the retina, the light-sensitive layer at the back of the eye. Instead of meeting at one clear point, light spreads across multiple points, which causes blurred or distorted vision. This focusing problem can make fine details harder to see.

Objects both near and far may appear blurry, stretched, or less sharp than usual. Many people are born with astigmatism, although it can also develop after an eye injury or certain eye surgeries. In some cases, increasing astigmatism may be linked to a condition in which the cornea gradually becomes thinner and more curved over time.

11. Presbyopia

Presbyopia is an age-related cause of blurred vision that affects your ability to see objects up close. As you age, the natural lens inside your eye gradually becomes less flexible. When the lens loses flexibility, it cannot change shape easily to focus light from nearby objects. This change makes close tasks harder to see clearly.

Blurry near vision, eye strain, and headaches after close work are common signs. Many people first notice presbyopia in their early to mid-40s. You may find that you need to hold books, menus, or phones farther away to read them clearly.

Presbyopia affects most people as they grow older, even if they have never needed glasses before. If you already wear glasses for distance vision, you may need a new prescription to help with near vision as well. Reading glasses, bifocal or multifocal lenses, and some contact lenses can help focus light more clearly on the retina.

12. Chronic Dry Eye Syndrome

Chronic dry eye syndrome occurs when the eyes do not produce enough tears or when tears evaporate too quickly. Tears form a thin protective layer that keeps the surface of the eye smooth, moist, and clear. When this tear layer becomes unstable, the surface of the eye dries out and becomes uneven.

This irregular surface scatters light entering the eye, which can make vision appear blurry or fluctuate during the day. You may notice that blurred vision improves after blinking because blinking spreads fresh tears across the eye. Other common symptoms include burning, redness, a gritty feeling, and sensitivity to light.

Some people also experience watery eyes as the body reacts to dryness. Dry eyes become more common with age. Hormonal changes, long periods of screen use, contact lens wear, smoke exposure, and dry air can all contribute. Certain medicines, such as antihistamines and some blood pressure drugs, may also reduce tear production.

13. Pregnancy

Pregnancy can affect vision because hormonal changes influence many parts of the body, including the eyes. During pregnancy, the body often retains more fluid, and this extra fluid can slightly change the shape and thickness of the cornea, the clear front surface of the eye.

Even small changes in the cornea can affect how light focuses and cause blurred vision. Hormonal changes may also reduce tear production, which can lead to dry eyes and irritation. Contact lenses may feel less comfortable because of this dryness. These vision changes are usually temporary and often improve after delivery.

In some cases, they can signal a more serious condition. High blood pressure related to pregnancy, including preeclampsia, can affect the eyes and cause symptoms such as spots, flashing lights, or trouble focusing. Seek medical attention right away if blurred vision occurs with severe headache, swelling of the face or hands, or pain under the ribs.

14. Eye Floaters

Eye floaters appear as small spots, threads, or cobweb-like shapes drifting across your vision. They develop inside the vitreous, the clear gel that fills the center of the eye. As you age, the vitreous slowly becomes more liquid.

Tiny fibers or bits of debris can then clump together inside the gel. Floaters may also appear more often in people who are very nearsighted or after eye injury or eye surgery. When light enters the eye, these clumps cast small shadows on the retina, the light-sensitive layer at the back of the eye. These shadows appear as drifting shapes in your field of vision.

They are often easier to notice when you look at a bright, plain background such as a blue sky or a white wall. Floaters often move with your eyes and may seem to slide away when you try to look directly at them. In most adults, floaters are common and usually harmless. Many become less noticeable over time, so simple observation is often enough.

15. LASIK

LASIK is a type of laser eye surgery used to correct certain vision problems. Vision problems such as nearsightedness, farsightedness, and astigmatism occur when the cornea, the clear front surface of the eye, does not bend light correctly. Because of this, light does not focus precisely on the retina at the back of the eye, which causes blurry vision.

During LASIK, a laser reshapes the cornea so that light focuses more accurately on the retina, improving how clearly you see. The procedure usually takes about 20 to 30 minutes. Anesthetic eye drops are placed in the eye, so the person remains awake but feels little to no pain.

After surgery, it is common to experience temporary blurred vision while the eye heals. Some people also notice dry eyes, glare, halos around lights, or mild eye soreness during the recovery period. In some cases, vision may be slightly under-corrected or over-corrected, and glasses or contact lenses may still be needed for certain tasks.