Causes of Blurred Vision: A Checklist of Possible Causes

14 December 2023

By Author: Alex J Shortt

Blurred vision isn’t a straightforward symptom with a one-size-fits-all explanation; instead, it serves as a potential indicator of underlying vision issues.

While the causes of blurred vision may be varied, it is often linked to cataracts, a condition where the eye’s lens becomes cloudy. The clouding obstructs light, affecting the sharpness of images on the retina. As cataracts progress, visual clarity diminishes, leading to blurred vision. Common symptoms include difficulty focusing, glare sensitivity, and a gradual decline in eyesight. Cataracts are typically associated with ageing but can also result from injury, medication side effects, or underlying health conditions. Surgical intervention, such as cataract removal and lens replacement, is an effective solution to restore clear vision for individuals affected by cataracts.

At Optegra, we are true eye care experts, specialising in cataract surgery, laser eye surgery, and lens replacement. Our expert surgeons treat tens of thousands of patients at one of our dedicated eye hospitals or clinics.


What Are The Causes Of Blurred Vision?

Gradual blurred vision can frequently be attributed to prescription-related issues, underscoring the importance of regular eye tests. Changes in vision may result from an outdated prescription or an underlying refractive error. Acutely blurred vision may be a sign of a serious infection or injury. It’s also crucial to recognise that blurred vision can be a symptom of underlying health conditions such as diabetes or hypertension. Booking an eye test allows optometrists to assess the current state of one’s vision and provide the appropriate management and diagnosis of the presenting condition, including, where applicable, the prescribing of corrective lenses. .


High Blood Pressure and Diabetes

Blurred vision can often serve as a warning sign of underlying health issues, with high blood pressure and diabetes being notable culprits. In cases of hypertension, elevated blood pressure may damage the delicate blood vessels in the eyes, leading to fluid leakage or swelling in the retina, causing blurred vision. Similarly, diabetes can result in diabetic retinopathy, where prolonged high blood sugar levels harm the blood vessels in the retina, affecting vision.

Given the potential gravity of blurred vision as an indicator, it becomes crucial to seek advice and referrals from your general practitioner. GPs can conduct comprehensive assessments, evaluating not only the ocular health but also the broader health implications. Timely intervention can help manage conditions like hypertension and diabetes, preventing further complications that may exacerbate blurred vision.

Blurry vision can also be a symptom of undiagnosed diabetes. Elevated blood sugar levels may cause the lens in the eye to swell, affecting its ability to focus and leading to blurred vision. Recognising this link underscores the importance of regular health check-ups, allowing for early detection and management of diabetes, thus minimising the impact on vision.

Blurred vision can be a symptom of high blood pressure or diabetes

You May Have Developed Cataracts

Cataracts, a common eye condition, can significantly impact visual clarity and manifest as persistent blurry vision. Here’s how this happens:

Lens Clouding:

At the heart of cataract-induced blurry vision is the clouding of the eye’s natural lens. The lens, responsible for focusing light onto the retina, should be clear. However, over time, due to factors such as ageing, injury, or genetics, the proteins within the lens may clump together, causing cloudiness.

Light Scattering:

As cataracts progress, the clouded lens scatters and diffuses incoming light. This light scattering disrupts the precise formation of images on the retina, leading to a lack of sharpness and focus. The scattered light results in a hazy or blurred appearance of the visual field.

Progression of Symptoms:

Initially, individuals with cataracts might experience mild blurriness, often mistaken for a gradual decline in eyesight associated with aging. However, as the cataracts advance, the blurriness becomes more pronounced, impacting daily activities such as reading or driving.

Addressing Cataract-Induced Blurred Vision:

The good news is that cataracts are an easily treatable condition. Cataract surgery involves the removal of the cloudy lens and replacement with an artificial intraocular lens (IOL). The procedure not only restores clarity but often improves visual acuity, helping individuals regain sharper and clearer vision.

Dry Eye Syndrome is a Common Cause  of Blurry Vision

Dry eye syndrome, characterised by insufficient tear production or compromised tear quality, has an impact on visual acuity. The tear film, comprising lipid, aqueous, and mucin layers, is integral to maintaining the corneal surface’s optical integrity. Disruptions in this tri-layered structure can induce refractive irregularities, leading to a manifestation of visual disturbances and prominently blurred vision, particularly during tasks requiring sustained focus where the blink rate is reduced.


The Connection of Glaucoma and Blurred Vision

Glaucoma, often termed the “silent thief of sight,” can present a subtle yet insidious onset of blurred vision, marking the beginning of a progressive visual impairment. This ocular condition is characterised by elevated intraocular pressure, causing damage to the optic nerve over time. The optic nerve, vital for transmitting visual signals to the brain, undergoes gradual degeneration, leading to peripheral vision loss.

Vision loss in glaucoma is typically gradual, occurring over an extended period of time before manifesting noticeable symptoms. The initial stages of glaucoma may be asymptomatic, making early detection challenging without regular eye examinations. As the disease advances, individuals may experience peripheral vision constriction, leading to tunnel vision. Blurred vision becomes a common manifestation as the optic nerve sustains progressive damage. Given its asymptomatic nature in the early stages, routine eye check-ups are pivotal for timely diagnosis and intervention to mitigate the long-term impact of glaucoma on visual acuity.


Eye Infections

Various eye infections can contribute to blurred vision. Bacterial conjunctivitis, commonly known as “pink eye,” can result in blurred vision due to the inflammation and discharge affecting the eye’s surface. The presence of pus and debris can obstruct the visual axis, leading to a temporary reduction in clarity. Similarly, viral conjunctivitis, often accompanied by redness and watery discharge, can induce blurred vision as the infection progresses.

Corneal infections, such as keratitis, are another source of visual disruption. Microbial invasion of the cornea can lead to inflammation, causing pain and light sensitivity, ultimately affecting visual acuity. Fungal infections, though less common, may also severely impact vision by causing corneal damage.

Recognising the signs of eye infections, including redness, discomfort, and discharge, is crucial for prompt diagnosis and appropriate treatment. Ensuring good hygiene and refraining from using contact lenses when swimming and showering can help prevent sight loss and serious eye infections. Timely intervention by healthcare professionals can mitigate the risk of complications and restore visual clarity in cases where infections contribute to blurred vision.


Other Possible Causes of Blurred Vision

There are several other potential causes of blurry vision. The most obvious of these are refractive errors such as astigmatism, myopia, or hyperopia, when the eye struggles to focus light accurately onto the retina. Additionally, macular degeneration, a progressive deterioration of the macula, can cause central vision loss, leading to blurred or distorted sight.

Neurological conditions like optic neuritis, characterized by inflammation of the optic nerve, may induce blurred vision, often accompanied by pain with eye movement. It is crucial for individuals experiencing persistent or sudden blurred vision to seek medical attention promptly.


Can Lack Of Sleep Cause Blurred Vision?

During sleep, the eyes have an opportunity to recover and replenish. Insufficient sleep can cause eye fatigue, making it challenging for the eyes to focus and maintain clarity.


What Causes Sudden Blurry Vision in One Eye?

Blurred vision in one eye can be attributed to various factors, and refractive errors are a common cause. These occur when the shape of the eye prevents light from focusing directly on the retina, leading to blurred vision. Myopia (near-sightedness), hyperopia (farsightedness), and astigmatism are examples of refractive errors that can affect one eye more than the other. Inconsistencies in the way light is bent by the cornea and lens can result in a lack of sharp focus, causing blurred vision in a specific eye.

Migraines, too, can contribute to transient blurred vision, often accompanied by other neurological symptoms. Some individuals experience visual disturbances known as auras during a migraine, which may involve seeing flashing lights, zigzag lines, or temporary blind spots. In the case of ocular migraines, these visual symptoms can affect one eye and resolve within a short period of time. The exact mechanism behind migraines causing visual disturbances is not fully understood, but it is believed to involve changes in blood flow and electrical activity in the brain that impact vision.

It is crucial to note that any sudden or persistent blurred vision, especially in one eye, should be promptly evaluated by an eye care professional. Other potential causes, such as vascular issues, eye infections, or more serious conditions like retinal detachment, could also be contributing to the visual impairment and may require immediate attention to prevent further complications.


Seeking Medical Assistance for Blurred Vision

When individuals experience blurred vision, the general practitioner (GP) or optometrist often serves as the initial point of contact for addressing vision-related concerns. GPs and optometrists are well-equipped to assess common causes of blurred vision, such as refractive errors or eye infections, and can provide necessary referrals to specialists if needed.

However, certain symptoms accompanying blurred vision may indicate a more urgent situation requiring immediate attention at the Accident & Emergency (A&E) department. If an individual notices sudden and severe blurred vision accompanied by other alarming symptoms like facial drooping, difficulty speaking, or weakness on one side of the body, it could suggest a potential stroke or other serious neurological condition.


What Are The Treatments For Blurred Vision?

The treatment for blurred vision depends on the underlying cause. Refractive errors, such as myopia or hyperopia, are often corrected with prescription eyeglasses or contact lenses. These optical aids help to properly focus light on the retina, improving clarity of vision. Astigmatism, another refractive error, may be addressed with toric lenses or refractive surgery, most commonly LASIK.

Cataracts, a common cause of blurred vision, can easily be corrected via cataract surgery. At Optegra, we are true cataract surgery specialists, with 99.6% of surgeries completed being uncomplicated.

Eye drops are commonly used for various conditions, including dry eyes or certain types of glaucoma. Topical lubricants help reduce the symptoms of dry eyes, while glaucoma eye drops aim to reduce intraocular pressure.


What Next? Get in Touch for Free, No-Obligation Advice.

At Optegra, we carry out tens of thousands of successful cataract procedures each year. We have a Trustpilot score of excellent. Learn more about cataract surgery at Optegra or book a no-obligation, free consultation for expert help and advice.

Alex Shortt Headshot

By Author: Alex J Shortt

Mr Shortt is a leading ophthalmic surgeon and an expert in the fields of cornea, cataract and refractive surgery.

Medically Reviewed Date: 14th December 2023


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