Why Do I Get Blurred Vision

Our eyesight is one of the most important senses that help us live normal and happy lives. We use our eyes to conveniently see things effortlessly so much so that any deviation in this function affects our lives significantly. But what causes us to have blurry vision?

Commonly, your vision can get blurry when your eyes fail to focus light properly as in astigmatism, long- or short-sightedness, when you have a cataract or glaucoma, and when the eyes get affected by diseases  such as diabetes, hypertension, injuries, infection or age-related macular degeneration.¹

While knowing the causes of blurred vision is vital, how do we identify the problem, how can we prevent or treat it and when should we seek medical attention? These are areas we will explore further in this article.

What is blurred vision?

Blurred vision refers to a situation where the vision is not sharp or clear enough. This makes it inconvenient to read or carry out other daily routines. When our vision is hazy or not clear, it might be pointing to a serious eye disease or even affecting the whole body. The blurriness  of vision can affect one or both eyes and can be associated with other symptoms such as visual loss, eye pain, or systemic diseases. 

Causes of blurred vision

To understand the causes of blurred vision, it will help to know a bit about how the eye works. Several structures in the eye work together to enable us to see but the key among them include the cornea, lens, retina, and the optic nerve. The cornea is a transparent barrier in front of the eye that contributes to about one-third of the refractive power of the eye.² The lens is a unique structure in the eye that has the power to focus light and can modify its form to focus light depending on the distance and form, a property known as accommodation.³ The retina is the photosensitive and receptor-rich layer at the back of the eye which carries light impulses and converts them to nerve signals that are passed to the optic nerve.⁴ 

Images are formed when light passed through the cornea which bends the light as it passes to reach the lens. The lens further focuses the light to fall on the retina, which is a light-sensitive layer at the back of the inner eye. From the retina, the light is converted into signals which pass to the brain through the optic nerve to form the images we see.⁵

Blurred vision can therefore occur when any of the above processes are impaired as a result of damage to the structures or foreign body affecting how light is passing across its pathway. The following are common causes of blurred vision:

1. Tiredness and prolonged screen time can lead to dry eyes and blurred vision. (NHS)
2. Age. In a condition known as Presbyopia, the power of the eye naturally becomes reduced, leading to blurred vision. (American Academy of Opthalmology) Another related condition that causes blurry vision in the elderly is age-related macular degeneration. In this condition, the retina is damaged in a way that makes the central visual field blurry but the peripheral field is intact
3. Abnormal axial length of the eye, so that instead of light focusing on the retina, it falls in front (short-sightedness) or behind the retina (long-sightedness)
4. Impaired ability of the cornea or lens to properly focus light. When the shape of the cornea is distorted (as in astigmatism) or affected by ulcers or lacerations, the sharpness of vision is reduced. Commonly, vision becomes blurred because the lens becomes opaque, a condition known as cataract
5. When diseases like diabetes and hypertension are poorly controlled, they lead to diabetic retinopathy and hypertensive retinopathy, respectively, and damage structures such as optic nerves and blood vessels, leading to blurred vision
6. Infections affecting the cornea (keratitis), uvea or middle layer of the eye (uveitis)
7. Trauma causing damage to the eye 

Signs and symptoms of blurred vision

While blurred vision is itself a symptom, you might have other associated symptoms  such as headache, squinting, visual loss, or other symptoms of the underlying cause as in the case of diabetes or hypertension.⁶

When you see a doctor, your eye examination might reveal refractive error, a situation where your eyes are unable to focus light properly on the retina. There may also be opacity in your cornea or lens. On visual field examination, the central or peripheral visual field may be affected. 

Management and treatment for blurred vision

Blurred vision is managed according to the causes. In refractive errors, corrective lenses can be recommended. Surgeries are usually performed in cases of advanced cataracts and glaucoma while proper control of diabetes, hypertension, and glaucoma is achieved  with drugs. In addition, laser surgeries such as LASIK can be done to correct refractive errors.⁷

How can I prevent blurred vision?

Blurred vision can be prevented by adhering to general eye hygiene such as avoiding eye fatigue by taking intermittent breaks from screentime, regular eye checks, maintaining regular diabetic eye exams, control of blood pressure, and wearing prescribed corrective lenses to prevent worsening of vision. In people who are exposed to danger in their occupations, it is recommended to wear protective goggles to prevent injuries.

When should I see a doctor?

While blurry vision that occurs due to eye strain easily improves by taking rests, any blurry vision that affects one eye, suddenly or rapidly worsening, associated with headache, or in the context of diabetes and hypertension, requires a consultation with a doctor.

FAQs

Who does blurry vision affect the most?

The elderly age group is mostly affected by blurry vision and this is why a regular eye exam is strongly recommended in this age group.

What happens if blurry vision is untreated?

Blurry vision usually progresses and might lead to permanent or reversible blindness

What are the red flags associated with blurry vision?

Seek medical attention immediately if blurry vision occurs:

1. Suddenly and rapidly deteriorating
2. Affecting one eye
3. Associated with pain
4. Associated with trauma
5. Associated with diabetes and hypertension

Should I rub my eyes to improve my blurry vision?

No. This can further worsen your symptoms or get your eyes infected

I work on my computer for long hours, how can I protect my eyes?

Take breaks every 20 mins by taking your sight away 20 feet from the screen for about 20 seconds(NHS). This will prevent you from having dry eyes and blurry vision.

Summary

Blurry vision is a symptom of several eye conditions and can best be described as a reduction in the clarity of vision. Sudden onset of blurry vision, rapid deterioration, involvement of a single eye, or in cases of hypertensive or diabetic retinopathy, consultation with a doctor is recommended. To prevent this problem, keep your eyes clean, do routine eye exams , take regular breaks from screen time, and minimise the risk factors for developing chronic diseases  such as diabetes and hypertension.